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k1atn
September 15th, 2014, 08:06 PM
Hi, I finally wired up my Altair 8800 and put a California Computer Systems Z80 Model 2810 CPU board in it, as well as an S.D. Sales/Systems 4K Low power static RAM board in it. I then hooked up the display/control board, and fired it up. Well... The CPU boards Interrupt light is on as well as the front panel's INTE light, the MEMR light is on, the INP is dim, M1 is on, OUT is very dim, the WO the light is on, and the WAIT light is on. The lights for A0-A15 are on with all of them being a very tiny bit dimmer than normal. The Interrupt LED on my CPU board is lit up to as i will show in the picture on the bottom of the page. The problem I'm having is that I can't toggle in anything. I tried entering the sample program from the Altair operators manual, using the switches under D7-D0, and absolutely nothing happened. The reset switch is the only switch that does anything either besides the power switch. I'm new to the altair, so I may be doing something wrong so could somebody help me please?

Thanks.

Two pictures are of the front panel, and one picture is of the Interrupt LED Lit on the CPU board.

20483

20484

20485

Chuck(G)
September 15th, 2014, 08:30 PM
Have you debugged the front panel? The Altair 8800s are notorious for iCs going bad, particularly the plastic ones. Also, the power supply capacitors (particularly if you have the "A" supply) usually are dried out by now. A scope would be very handy for this.

JDallas
September 15th, 2014, 09:16 PM
...The problem I'm having is that I can't toggle in anything.
Did you try SINGLE STEP switch in both positions?

You might try turning off RUN and stepping it through its initialization after a RESET. If you see it change state, SINGLE STEP to SINGLE STEP, that will tell you that at least most of the panel in running and then figure out WHAT the microprocessor is doing. As the LEDs are dimming, it might suggest that its running an interrupt polling loop... no real idea as I have no information on the Z80 board. It might have a power-on code insertion to jump to a ROM monitor (Like the Cromemco ZPU). That first command would be C3.nn.nn if I remember my Z80 machine code from the late 70s.

k1atn
September 15th, 2014, 10:58 PM
Well, I've checked the capacitors, with an ocilloscope, and they're all in perfect working order :) , I at least got it out of what it WAS doing, and the deposit switch ONLY working and it now reads random data as my dad says, which shouldnt be as there is no data there. when i hit the switch it cycles through something???, i dont know what yet. it also looks like my address and data lines are mixed up, A0 is currently located at A4, and A1 is currently located at A5. so i'm hopefully going to fix that issue, as for the data lines being mixed up, my dad, who owned the altair before i did, said not to worry about for the moment. It still won't examine, run/stop or toggle things in yet though.

k1atn
September 16th, 2014, 01:00 AM
JDallas, I cant use the RUN command or SINGLE STEP at the moment, they don't work. RESET was the only one that worked, but now the DEPOSIT and DEPOSIT NEXT does something but i don't think it's doing the right function, like i said my data lines and address lines are mixed up, the DEPOSIT/DEPOSIT NEXT switch isn't depositing, it's switching through the memory addresses, so maybe its acting like the EXAMINE/EXAMINE NEXT switch, so maybe that's one of the data lines that is mixed up.

Corey986
September 16th, 2014, 02:04 AM
What is the exact power on procedure you are using?

Make sure you press stop and reset at the same time at least once to put the CPU in a known state before doing anything. Most people think you only need to press reset. Not true on the Altair for power up. You should do both at the same time.

k1atn
September 16th, 2014, 03:26 AM
I don't know what you mean exactly by power on procedure, i just turn the unit on, and wait for it to try to set to ready, but what is happening is that as soon as I turn it on it starts reading from memory, and CONSTANTLY too, or so my dad says, he also says it's trying to execute a program, but as far as i know there's nothing in memory and also the on-board ROM on the CPU board that should contain the Moss 2.2 Monitor, is blank because the board had no ROM chip when i got it and i had to order one and i made sure it's the proper chip too. i have the .bin and . cue files, i just don't have an Eprom programmer that can interface with my computer because my programmer is from the 70's and it needs repairing anyway. i found out about the stop and reset at the same time thing when i hit run after power up and deposit didn't work anymore, i hit stop and reset at the same time and deposit worked again, but nothing else. but like i said the deposit switch is acting like the examine switch so when i say deposit worked or didn't work, i mean that it either cycled through memory when i toggled it or it did nothing.

Here's a little video of what i'm talking about, maybe it'll help. It shows me toggling all the switches on the bottom, individually except for protect/unprotect,also deposit (cycling) and then hitting run and then deposit (not working) then hitting reset and stop at same time then deposit (working again).


https://www.youtube.com/watch?v=1lrBOA4kMD0&list=UUpIt2nT1CeQsHnjGQkss1Hw

Marty
September 16th, 2014, 06:02 AM
Hi All;
K1atn, You are sort of close, most likely as previously stated, yuou have some Ic's that are not goot or the solder need touching up, or a Bad switch..
As per the Stop and Reset, hold Your Hand, Palm down (I use my left, even though I am right handed), and place my first finger on the Stop/run switch and my thumb on the Reset switch..
I push up on the Stop Switch with my first finger and at the same time, while holding it up in the stop position, I then push the Reset switch with my thumb holding both for a second.. Release the reset first, then release the stop switch.. Sometimes You need to do this more than once..
Since it is a Z-80 Board, it might not this, but it is a good idea or good habit just to do it after first power up..
Also the D0-D7 on the cable are not wired D0 thru D7, the order is different.. I will later when I have time look it up..
You could have Bad Ic's on any of the Boards or on the Front Panel..

THANK YOU Marty

glitch
September 16th, 2014, 11:04 AM
If you don't know the state of your CPU and RAM, you'll have to start with those. I typically start with a "HALT ROM" or by hardwiring a HALT onto the the bus with a protoboard. Having a known-working CPU is going to make debugging the front panel a lot easier.

Dwight Elvey
September 16th, 2014, 11:17 AM
Your address problem sounds like you have the data wires
from the front panel plugged in upside down.
Oops! I see Marty mentioned that.
The front panel needs a working processor to do things.
C3 is used and can tolerate the D0 to D7 swapped with
D7 to D4 but it still does strange things.
Other swaps will not work right at all. Trace the wires
on the front panel to the processor.
Dwight

k1atn
September 18th, 2014, 03:27 PM
Okay I just traced the wires, and 72 (PRDY) and 68 (MWRITE) were switched, 45 (SOUT) was in a hole that wasn't marked, and 54(EXT CLR) was on 45. So I fixed those and they are as they should be now. I then fired it up, and the stop/run, single step, and examine/examine next switches function again, as well as the deposit switch. But the computer still won't let me jump to an address, or deposit new data. and it's still currently reading random data.

Here's a video of what I mean.

https://www.youtube.com/watch?v=vmjJuXU16xk

Marty
September 18th, 2014, 05:02 PM
Hi All;
K1Atn, You have made good progress.. You stated that both Examine and Deposit work, But, that is only Partially true, as Deposit will advance the Address, but it will not actually Deposit.. But, that Is still progress..
Also the D0-D7 on the cable are not wired D0 thru D7, the order is different.. Here is the correct order from Left to Right on the 8 or 10 pin Connector that plugs into the CPU Board.. D3, D2, D1, D0, D4, D5, D6, D7.. My Altair has a 10 pin connector, but only 8 are used..
Also, Could You post a Picture(s) of Each of the Boards that Your Machine has in it, such as the Z-80 CPU board, the Memory Board(s), the I/O (serial) board.. Also the Connector..

Here are some Pictures of what I have for Reference, they are the connector, 8080 CPU and Serial I/O Board and a converter connector for Altair to Imsai.. They may be Blurry, as I never know till I have uploaded them..

20511 20512

20513 20514 20515

THANK YOU Marty

k1atn
September 18th, 2014, 07:08 PM
Marty, I think my data wires are wired right. Reading the labels on the front of the display/control board where the wires connect, D7 is blue, D6 is yellow, D5 is red, D4 is black, D3 is grey, D2 is dark blue, D1 is the second yellow on my cable, and D0 is the second red. As i show in one of my pictures, the color pattern of the wires going into the socket on the CPU board match if you compare the color coding i mentioned above and match it to the labels right above the socket on the CPU board. Here are the pictures, BTW I don't have an I/O board yet. Also my front panel data connector on my CPU board is 16 pin but it only uses 8 pins for data as you can see in one of my pics.

20516

20517

20518

20519

20520

k1atn
September 18th, 2014, 09:55 PM
Here's the last picture showing what i was talking about with my wiring for my data lines. For some reason it only lets you post 5 photos per post. The reason the other wires are cut off is because i don't think i need them. it seems that in a z80 CPU board manual similar to my own it shows the wiring diagram for connecting it to a front panel display. 2 wires would connect to one spot on the display board (Wires 1, and 16=D0, wires 2, and 15=D1, ect. ect. which equals the 16 pin socket on the CPU board, but the way i see it, all i need is 8 pins, 8 wires so i use half the socket and therefore the other wires are cut off in the photo.

20521

Frank S
September 18th, 2014, 11:19 PM
I think my data wires are wired right...
I don't think so.
The order from the edge of the front panel PCB is: D7,D6,D5,D4,D3,D2,D1,D0
e.g. in your wiring D0 has a red color and is connected to D5 or D1 on the front panel.

Frank

k1atn
September 18th, 2014, 11:54 PM
Yep, you're right. i have D0 and D1 switched. I'll fix that later today. As for the red being connected to D5, there are two red wires, one is connected to D5 and one is supposed to be connected to D0.

Marty
September 19th, 2014, 05:20 AM
Hi All;
K1Atn, You have the Imsai style of connector, on Your Z-80 Board, so the 8 wires You have is correct, Just have to fix the Order, as Frank already stated..
Since You have a multipurpose Z-80 Board, which already has a Serial connection, (top Left hand Corner), You don't need another one for now..
Also, since it has an Eprom, installed as well and it might automatically be Jumping to that Memory Location, You would Not be able to use the Deposit/Deposit Next in that area of the Memory..
Also, You need to check that Your Memory Board is Addressed for Starting at '0000 and not some other address..
Once You have D0 and D1 fixed, Please let us know of any progress..

THANK YOU Marty

k1atn
September 19th, 2014, 09:58 AM
Got the wires fixed, and they are as they should be now, Below is a picture showing exactly how i set the board up which is for the first 4k block. Also since you mentioned that it might be automatically jumping to the Eprom memory, what would happen if I took the Eprom chip out? Because originally when i got that board it did not have an Eprom installed, i went and bought one.

Thanks again for all your continuing help, it is very appreciated.

20523

glitch
September 19th, 2014, 10:07 AM
There should be an option for disabling power-on-jump to the EPROM on the CPU board. As I discovered with my Vector Graphic ZCB, disabling the feature may not entirely work as desired (the ZCB still asserts /PHANTOM, which will lock out some RAM boards). There are several different power-on-jump strategies common to S-100 boards, in my experience it seems like asserting /PHANTOM and mapping the internal EPROM socket to 0x0000 is the most common for CPU boards with integrated EPROMs.

k1atn
September 19th, 2014, 10:45 AM
yeah i have the power on jump to Eprom as well as phantom enable jumper disabled. I took the Eprom chip out, just to see if there would be a change from it maybe jumping to Eprom memory. the chip is blank so i guess it wouldn't hurt the board anyway as the CPU board had no Eprom chip in it when i bought it to begin with. Still no change though.

Marty
September 19th, 2014, 11:35 AM
Hi All;
K1Atn, for now assuming that You do indeed have the Eprom disabled, then having the Eprom in or out would make No difference..
So I would concentrate on looking at the Signals, on the Z-80 and on the Buss that have to do with Reading and Writing to the Memory.. Start from the the Memory Board and Look at the RD and WR signals tracing them back to the Z-80.. If they look the same, then You have a problem..
Also, check to see that You Aren't fighting Yourself, that the MWRT coming off of the Z80 Board is turned off or dis-connect from the Buss, since You are using You Front Panel for these signals and Not the Z-80, since at this point You are not using the Eprom for a Software Monitor to replace the lights and switches of the Front Panel..
Let us know what You find..

THANK YOU Marty

k1atn
September 19th, 2014, 11:55 AM
I'll check into that, BTW if anyone want's to give it a quick read and let me know if i'm doing something wrong according to the manual for my particular CPU board, here it is.

https://drive.google.com/file/d/0B_9RVw-3-nFoRkZ6anprOHpzb0E/edit?usp=sharing

Marty
September 19th, 2014, 12:08 PM
Hi All;
K1Atn, Thank You for the Link, I am Reading thru it and will let You know what or If I find anything..
It mentions the Phantom Line, Since the origional Altair Didn't have a Phantom line, I would for Now at Least until You can get more of Your system running with the Front Panel, Turn it off or dis-connect it from the Buss.. It could be turning off Your Memory or disabling it..

THANK YOU Marty

k1atn
September 19th, 2014, 12:20 PM
Phantom's off on the board

Marty
September 19th, 2014, 12:28 PM
Hi All;
K1Atn, I would dis-connect or dis-able W26 thru W30, as well..
Also, IF I can get the PDF pages of the Monitor to copy to Notepad and then Assemble them, Possibly I can Program a 2716 for You.. It mostly depends on, If my SSM PB-1 will work anymore and If I can get a file made that I don't have to enter Manually.. I Just tried to copy to notepad.. Too many errors and too much missing.. So I will try some other things..

THANK YOU Marty

k1atn
September 19th, 2014, 12:57 PM
Here's the Eprom file .bin and . cue, I don't know if i can find a pdf for the Moss 2.2 monitor i had a really hard time finding the eprom file for it. luckily someone on this forum from one of my posts last year sent me a link to it.

https://drive.google.com/folderview?id=0B_9RVw-3-nFoRnVXdnpSbUxLM2M&usp=sharing

Marty
September 19th, 2014, 01:16 PM
Hi All;
K1Atn, Thank You for the link for the .Bin file..
The Listing for the Moss 2.2 Monitor is in the Manual that you listed earlier, about page 75 and up..
Please give me some time and I will see what I can do..
I can Immediately Send You a 2732, Loaded as a 2716, in the lower addresses.. And What You have to do is Bend Pin 21 out and Tie it to Ground, ( with a wire wrap wire) instead of +5 which is what the socket has it tied to.. Then the 2732 should work as a 2716, and You should be good to Go.. If You want to go that Route..

THANK YOU Marty

k1atn
September 19th, 2014, 01:38 PM
sure we can go that route, so instead of putting pin 21 into the socket on the CPU board with the rest of the pins, i just solder a wire to it and ground it to any ground source... say ground it to the chassis or tie it to ground on the buss?

Marty
September 19th, 2014, 01:50 PM
Hi All;
K1Atn, tie the Ground to another Ic on the Z-80 Board OR to the Ground Pin on the 2732, (I think pin 12)..
I will Send You a Personal Message here on the Forum..

THANK YOU Marty

k1atn
September 19th, 2014, 02:07 PM
sent pm back

Dwight Elvey
September 19th, 2014, 04:05 PM
I've forgotten which instructions are used by the front
panel to run but for the addressing for looking at an address,
it used the JMP instruction C3. It uses another instruction
for looking at that location ( as I recall ).
These instruction are sent to the Z80 over the data lines,
while the back plane data bus should be isolated from the Z80
and observed and controlled from the front panel.
The C3 is usually driven from a number of open collector
inverters ( or buffers ).
It is quite common for one or more of these to fail to drive
the Z80's data bus. or one of the address bytes to fail to
get to the Z80.
Use a scope or logic analyzer to observer the data pins
at the Z80 when you select an address to observe.
you should see the sequence C3 <LowAddr> <HiAddr>
on the Z80 data lines.
That will cause the Z80 to send the address onto the back
plane address lines.
Dwight

Chuck(G)
September 19th, 2014, 04:11 PM
If you don't have it already, the Theory of Operation (http://www.classiccmp.org/dunfield/altair/d/88theory.pdf) manual has a good section on how the display panel operates. And yes, look out for those 7405s--if any go bad, you can replace them with 7406s, which are a bit easier to find.

k1atn
September 19th, 2014, 05:39 PM
so to get this right, i use the ocilliscope and put it on the data lines D0-D7 on my CPU board while the front panel is hooked up to it and i observe what happens on each pin as i try to observe an address?

k1atn
September 19th, 2014, 07:06 PM
Marty, what do you mean by disconnecting W26-W30, do you mean disconnecting the wires coming from pins 26-30 on the buss as shown in the bus wiring diagram? and Chuck(G), I do indeed have the theory of operation manual as well as the operation manual, and Assembly/construction manual and Assembly hints for Mits Kits. They have been very helpful in me putting a half destroyed (meaning mostly and carelessly taken apart by me when i was 10 and the original boards are god knows where) Altair back together again. It's funny how you can grow up in your teenage years and suddenly learn to appreciate vintage electronics. Especially after my dad told me that the Altair had a major impact on micro-computing.

k1atn
September 19th, 2014, 08:20 PM
Okay, i did a few things. I measured the voltages on each data pin and they came out as follows... D7-5v, D6-1.1mv, D5-1.1mv, D4-1.1mv, D3-1.1mv, D2-1.1mv, D1-1.1mv, and D0-5v. I also measured the voltage of A0 on the bus as i tried to go to that address and in doing so found something interesting that made me test a couple of other switches with it. my dad said that when A0 is switched to on and examine is toggled it should put voltage on the bus and when examine is depressed the voltage should go down to zero. well here's what i found out. When i put the voltmeter on pin 79 (A0) there was no voltage, when i hit reset it showed 3.47v on that pin and when reset was depressed the voltage was again zero. I then switched A0 on and hit examine... the voltage went to 3.47v and stayed there even after the examine switch was depressed. It did this even when A0 was in the off position and i hit examine. Any input on this would be helpful.

Marty
September 20th, 2014, 01:07 AM
Hi All;
K1Atn, "" Marty, what do you mean by disconnecting W26-W30, do you mean disconnecting the wires coming from pins 26-30 on the buss as shown in the bus wiring diagram? ""
No, As shown in the Manual for the Z-80 CPU Board, these are the Jumpers for connecting and dis-connecting from the Buss, 5 signals that might interfere with the operation of the Front Panel.. Just like You did with the Phantom Enable, see page 90 of the Manual..
"" When i put the voltmeter on pin 79 (A0) there was no voltage, when i hit reset it showed 3.47v on that pin and when reset was depressed the voltage was again zero. I then switched A0 on and hit examine... the voltage went to 3.47v and stayed there even after the examine switch was depressed. It did this even when A0 was in the off position and i hit examine. Any input on this would be helpful. ""
Actually, this may be correct, for after you hit "Examine" any switch in the One position would show a High 3.47 volts there on its pin and hopefully on the Leds as well, since that is the address that You are examining and at this point see random data in the Data lights..
And now changing the Switches, so that if You would Press Examine again it puts what ever switches you have set in the "one" or up position and they are now being Examined..
I am a little unclear here about your response ""It did this even when A0 was in the off position and i hit examine. "" If having switched off A0 and Pressing Examine and A0 stays high 3.47 volts, then that is Wrong.. But, If A0 is on when pressing Examine and A0 buss pin (79) and the Led shows it being on and then pushing A0 to the off position, Without pressing Examine, then that is Correct, A0 should stay on..
But, If You change the Switches After pressing Examine, and instead Press "Deposit" then instead of another Address, You are changing the Data and the Data Leds should match Your first 8 switch positions.. Remember, that the Switches are for Both Address and Data, depending on whether you Press Examine or Deposit.. I hope this Helps..

THANK YOU Marty

Marty
September 20th, 2014, 06:33 AM
Hi All;
K1Atn, On another note, since You are poking around with Volt meter and oscilloscope leads.. And accidents can and do happen..
I would Very Strongly suggest that you do the following, as soon as You are able.. More about Able in a bit..
Disconnect the power leads to all of the Power Transformers and tape them up.. Leave all of the Transformers in the machine along with the Rest of the Origional Power Supply, and Then Mount a pair of Modern Switcher Power Supplies.. I will find the numbers that you would need, for these Switching Power Supplies..
Now for the Reasons !!!
As, stated way back at the beginning of these postings, the Capacitors, are about 40 some Years old, Old Caps do Not age very well.. They tend to Leak, Crack, Open and Short Out.. The Leaking and the Shorting out are what can do the most damage to Your Machine.. Also, since the origional Power Supply is Linear, it will keep on feeding voltage and Especially Amperage to what ever it is attached to.. Even a Short, like from Your Volt Meter Test Leads..
Whereas a Modern Switcher will automatically switch itself off when Presented with a short.. And save an IC, a Board full of Ic's Or the whole computer, before the machine can be turned off.. With the old supply it would have just kept on supplying power.. I know what can Happen, I've done it many Years ago, on an old Altair 8800b that I bought New.. A solder ball fell off of a board that I was repairing and shorted the 18 volt line to a 5 volt line and took every board out, before I could turn off the machine..
Also, the Switcher supplies provide a Cleaner voltage, Your Regulators will run cooler and provide a more stable voltage to the Various boards.. And You can switch it back to the origional Power Supply for when You want to take it to a show or something like that, and remove the Switchers..
But for Daily use and when poking around I would sure suggest using these switchers..
Now about Able, Since I don't know Your situation, I would see if Your Parents can Help You get these Switcher Power supplies, and then you could work something out with then, to pay all or part of the money back thru your allowance or thru Odd Jobs You could do around the House or in the Neighborhood..
The Power supplies that You would need to get are something like the following ::
One would be something like a MeanWell SP-150-7.5 OR a S-100F-7.5..
The Other Supply would be a MeanWell T-40C OR a T-60C..
These Power Supplies can be obtained from Digikey, Jameco, Mouser, etc..
If You go to Grant Stockly's site, there are instructions for wiring up these Supplies.. And I can be of help also..

http://www.altairkit.com

Here are some Pictures of my Altair wired with these supplies, and the Transformer wires taped off::

20547 20548

THANK YOU Marty

k1atn
September 20th, 2014, 08:04 AM
OK I'll get on that, I'm 23 now so i have my own money i just have to have enough to get the power supplies because i don't have a job yet. the SP-150-7.5 and the S-100F-7.5 are a little hard for me to find at least for a good price and in stock. Will a SP-100-7.5 do? Also when replacing the caps on the power supply board, the 6 silver 3300mfd caps say Arcolytic on them but the assembly manual says they're electrolytic. So now i need to know if i replace them with electrolytic 3300mfd capacitors or Arcolytic 3300mfd capacitors.

Chuck(G)
September 20th, 2014, 08:28 AM
Same thing, really, Arcolytic is just a trade brand of aluminum electrolytic.

As I mentioned, electrolytic capacitors of this age tend to dry out--they don't short, but they turn into what amounts to empty cans. That's why I asked you to use your o-scope to check for ripple on the PS output. Capacitors have also gotten a lot smaller over the years. If you're interested in preserving the appearance, you could open one of these old cans, discard the innards and stick a modern cap inside.

If you're looking for overvoltage/overcurrent protection, you can simply add a circuit to the output of your linear PS, rather than completely replace it. Linear supplies tend to have a much longer life (due to lower ESR heating on capacitors) than switchers.

k1atn
September 20th, 2014, 09:04 AM
Chuck (G), I just made a video showing what my scope shows when hooked up to each capacitor. I tested each capacitor before the video and they all showed the same thing. I left the scope on one capacitor for the video. Watch the red line because the blue one is CH1 on the scope and is not hooked up. The voltages in the video are from the scope it's just not in frame.


https://www.youtube.com/watch?v=UHvbNHtNWZE&feature=youtu.be

Chuck(G)
September 20th, 2014, 09:24 AM
Okay, you show a couple hundred mV of ripple, not too bad if there's a load on the PS. When you're measuring ripple, the PS should be under load and you can use the AC coupling on your scope to view ripple directly (the DC component won't show).

k1atn
September 20th, 2014, 09:29 AM
Alright, I have the measurements with the PS board under load. Here it is. Not sure how to use an AC coupling on my o-scope is is a Parralax USB Oscilloscope so it might not have that.


https://www.youtube.com/watch?v=_3LrmGUrCkQ&feature=youtu.be

Chuck(G)
September 20th, 2014, 10:49 AM
Okay, still about 2-300mV. Not bad for this one. So you can assume that the capacitors are okay.

Marty
September 20th, 2014, 11:56 AM
Hi All;
K1Atn, Sorry, I hope I didn't Offend about Your age, I just didn't know..
In answer to Your Question "" Will a SP-100-7.5 do? "" Yes, and since You don't have alot of Boards, possibly even a small one will do.. The main thing is that it is a 7.5 Volt unit..
Even though Your Caps Look Good, I still will stand by my position, that in case of a Short they will turn themselves Off and Protect Your system..
Also, in case You have Not done so, Take the Cover(s) off or from the Front Panel Led's and Switches and start checking what works and what doesn't work.. And use Your Scope.. And as I said previously start checking the Memory's ability to Read and be Written to..
I am going to send You a PM..

THANK YOU Marty

THANK YOU Marty

k1atn
September 20th, 2014, 12:15 PM
no, you didn't offend me at all, i was just saying how old i was. i will start checking those ic's on the front panel with the scope, i also re-soldered every connection i made just to be sure there were no solder bridges. interestingly no matter how many times i turn the unit off and on, whenever i flip an address switch and hit examine, it cycles through the same exact places and in the exact same pattern as if the memory is retained when the unit is off. for example i turn it on and flip A0 up, hit stop and reset, and hit examine a bunch of times, it cycles through data. I turn the Altair off and back on hit stop and reset, and flip address A0 up and hit examine again and it cycles through in the exact same way and pattern of lights. it's puzzling.

Marty
September 20th, 2014, 01:16 PM
Hi All;
My memory does the same thing quite often, I can't say why..
Just for the Fun of it, Try a different Switch, like A1 or A7, and see If it shows anything different.. And also try Examine Next After You Press Examine.. And see if anything changes.. Also, when You can get to the Front Panel Ic's, especially on the 7405's compare your outputs and Inputs and the Switch settings to these Ic's.. You should be seeing an octal 303 at least part of the time, So check D0 and D1, along with D6 and D7, when the input to each of them is High or Low (the 7405's) the output should be the opposite.. And the inputs to these should all be tied to the same place.. And Looking at the Front Panel Schematic, they pull the middle bits Low, D2, D3, D4, D5 via L10 "T", (pins 3, 4, 5, and 6) and all of the Bits and pulled High or Low via 00 "U" (Pins 1, 2, and 3) and trace them back thru the flip/flops and one-shots (74123's) back to the various switches.. I hope this helps..

THANK YOU Marty

k1atn
September 20th, 2014, 07:02 PM
My dad and I checked the inputs and outputs of IC "T" and IC "U" as well as a couple others and they are functioning exactly as they should. My dad is starting to think that my particular Z80 board is not compatible with my system because every single thing we have checked so far, Terminal block voltages, Power supply capacitors, Buss voltages, Buss connections to the display board, Switches and IC's, have all checked out functioning exactly as they should. So basically right now an incompatible board is all we can think of that might be causing this, and I don't think it's my memory board because the jumpers are set to address 0 and it says it's for Altair 8800 and Imsai 8080 systems in big bold letters right there in the manual.

ldkraemer
September 21st, 2014, 04:36 AM
I'm curious of you have checked the following Signals on the Z80 CPU.
The Z80 requires the following:

Pin 11 - +5VDC
Pin 29 - GND (+5VDC COMMON)
Pin 6 - /CLK (/CLK can be an external signal for manually clocking the CPU. But, if done this way, the /RESET Signal MUST BE LOW
for several /CLK cycles on Startup so the CPU gets reset properly.)

In addition to the above signals, the following Signals must not be ACTIVE (LOW or HELD LOW) or the CPU won't STEP.

Pin 16 - /INT
Pin 17 - /NMI
Pin 24 - /WAIT
Pin 25 - /BUSRQ
Pin 26 - /RESET

All other Signals are generated by the Z80 as Outputs from the Z80 to external circuits.

So, if you wanted to VERIFY all the Address Lines, you could modify a new 40 Pin IC socket to allow the Z80 to sequence
through all Address Lines (at /CLK frequency, or via an external /CLK signal) by bending D0 thru D7 over so that they WILL NOT be
connected to the Motherboard Z80 Socket. Then Jumper DO to D1, to D2, to D3, to D4, to D5, to D6, to D7, to GND. This in the same as
putting 0x00 (NOP) on the Data Lines for the Z80. (If stepping from an External /CLK, you will have to isolate the Motherboard /CLK
Signal too.) All Z80 Output Signal Pins can be slightly bent so they DO NOT go into the New 40 Pin IC Socket. That will eliminate
them for this test cycle.

By inserting the Test 40 Pin IC socket with a Known Good Z80 in the Motherboard, you should be able to scope out all the Address Lines (A0 thru A15)
and VERIFY that they are all toggling (HIGH & LOW), and aren't stuck LOW or HIGH. That will eliminate everything but the Data Lines D0 thru D7, and
Front Panel Wiring or Circuit Problems.

Be sure to start with verifying all Power Supply Voltages are within specifications.

20567

Larry

Marty
September 21st, 2014, 05:28 AM
Hi All;
K1Atn, ldkraemer has made some good points, of things to try..
You are making good progress, Don't give up yet or so soon..
Yet, I wouldn't completely jump to conclusions, about the incompatibility of Your Z-80 Board.. Its is good that you checked out Ic's "T and U" , But did You get when the proper codes on the Data Leds..
Remember at this point You Don't need the Z-80 Board in the machine.. Also, You have checked out some of the Ic's but not ALL of them in the Front Panel and in the Z-80 CPU Board and in the Memory Board.. It only takes One to mess the whole system..
When You have a Low on the OutPut of IC "T" what do You show on the Data Leds and then when there Is a High on the Output what do the Data Leds show.. Same thing with the output of IC "U".. Remember that by turning on these IC's and turning them off You are creating the Codes for a Jump Routine (Octal) 303 000 000 or even the inverse 074 111 111 on the Leds and the various 7405's should be able to put that out on the Data Lines..
Then, as I stated Yesterday, You still need to follow the signals back from these two Ic's to the Switches.. And make sure that the 74123's are putting out the Correct Pulse Length.. Check the Resistors and Capacitors, for Breakage and or value change, and Replace when in doubt..
Also, I keep on forgetting to Ask, is Your Z-80 Socketed and is Your Front Panel Socketed ?? There is Good and Bad, no matter which way You answer for each.. If they are socketed, then make sure that the connections are good and not corroded from 40 years of setting around, and If they are not they when You have to replace something, You have to clip it out and put in another Part, and when putting in another Part I would socket them with "machined Sockets" they are better and more expensive, but they are worth it..
THANK YOU Marty

k1atn
September 21st, 2014, 11:40 AM
On my unit, the pin 11 that's supposed to show +5VDC shows no volts, pin 29 shows no volts, Pin 6 on my unit is hooked up to VI 2 according to my Altair's bus structure diagram instead of /CLK like you said it should be.
The rest you talked about are hooked up according to my Altair manual's bus structure also.
Pin 16 on my unit is not hooked up at all on the bus according to the bus structure. You said that /INT goes there.
Pin 17 is not hooked up at all on the bus according to the bus structure diagram. You said that /NMI goes there.
Pin 24 on my unit is hooked up to 02 according to the diagram. You said that /WAIT goes there.
Pin 25 on my unit is hooked up to 01 according to the diagram. You said that /BUSRQ goes there.
Pin 26 on my unit is hooked up to PHLDA according to the bus diagram. You said that /RESET goes there.

On my bus structure diagram pin 27 is PWAIT, pin 75 is PRESET, and pin 73 is PINT you say they go on a different pin so what do i do, and what do i do about the no voltage problem on pin 11 and how do i ground pin 29?

Marty
September 21st, 2014, 01:31 PM
Hi All;
K1Atn, I think at least Partly, You are mixing up Z-80 pin numbers and Altair Buss Numbers..
Also, check a few other things, before making sure of something..
So, lets start with No +5 Volts on pin 11 of the Z-80..
First, make sure that You have counted the pins correctly, I have made that mistake before myself..
Next Go to the Regulator You have a 7805, So check that You have about +8 volts on one side and about + 5 volts on the other side of it, with respect to Ground..
Then Go to any other chip other than the Z-80 and on the top Right hand corner of most of the 14 pin or 16 pin Ic's locate pin 14 or pin 16 and check for the + 5 volts there, Check a number of them, and IF You get nothing either from the Regulator or from the Corner pin.. Then I would suspect that Your 7805 is Bad.. Before Rechecking the Z-80 itself, once You have the proper voltage coming out of the regulator, check other Ic's and then Recheck the Z-80 itself..
Once You have that Established, then we can go Point by point thru each of the other Signals that You have posted above, and Rechecking them one or two at a time..
I know that this can be overwhelming, but hang in there, and things will look brighter after some hand holding and Practice, with what is being referred to and what You are seeing..
Also, Take the Z-80 Board out of the Altair and "OHM" it from the middle pin of the Regulator to Both the Ground connection on the Altair Buss and to some 14 and 16 pin Ic's, only on pins 7 or 8 where most of the grounds are and on pin 29 of the Z-80 make sure You have that.. And do the same for the +5 pin on the Regulator, check with the Meter, that You have connections to pins 14 or 16 on most of the small ic's, and on the Z-80 on pin 11..
Once You have "THAT" done then we can go to the next set of points You raise in the above posting..
After turning my computer off, I had another thought.. So, I am back again..
With the Z-80 Board Plugged into the Buss, check that You ARE indeed getting the +8 volts to the Regulator and do the Same on the Memory Board.. Maybe, I doubt it, but it doesn't hurt to check.. That the Front Panel has the +8 volt coming to it and the Altair S-100 Buss Does not have the +8 volts coming to it, so check Both Boards !!

THANK YOU Marty

k1atn
September 21st, 2014, 04:48 PM
Okay i misunderstood, I thought you meant pin 11 on the Altair bus. Yes it shows 5v on pin 11 of the z80 CPU chip on the CPU board. The 7805 shows 8 volts on one side and 5v on the other just like you said it should. On the chip labeled WD8250-PL the voltage on pin 20 is 5v. Every single 16 pin IC shows 5v on pin 16. With the 7805's middle pin OHM'ed to ground (pin 50 and pin 100) on the Altair Bus it shows 0.24 ohms, and every single 16 pin IC when OHM'ed on pin 7 to the middle pin of the 7805 shows 0.09 to 0.16 ohms depending on the IC. pin 7 was the only one the ohmmeter lit up on. Also from the 7805's middle pin OHM'ed to pin 29 of the Z80 chip it shows 0.14 ohms. I am also getting connections from the +5v pin on the 7805 to the IC's and pin 11 on the Z80 chip. I also checked to see if the regulators are getting +8v, and they are indeed and so is the bus. The only socket on the bus not getting 8v is the first one in which pin 1 isn't getting 8v but every other S-100 socket on the motherboard is getting proper voltages including pin 1 on each one. I just don't plug anything into the first socket.

Marty
September 21st, 2014, 05:33 PM
Hi All;
K1Atn, Ok, Good progress,
Now Look at the Questions You posted on Page 5 of this Blog, and the Schematic (page 96) that You posted Earlier, and see IF that Resolves most if not all of Your previous Questions..
If, so, then we can move on Back to the Front Panel again.. and as I stated in that post You need to Really check out the 7405's and make sure they are putting out as they should.. Take the Z-80 Board out, and make the outputs of T and U "high" and "Low" and make sure on the data leds that You see are putting out the proper Response.. Otherwise, You need to make it so that they do and are putting out the correct values.. And work Your way back to the switches themselves.. Once that is done, and we Know that the Front Panel seems to be working correctly, we can move on to the Z-80 Board and the Memory board itself..

THANK YOU Marty

Marty
September 21st, 2014, 06:24 PM
Hi All;
K1Atn, I am going to Ask You to do something that seems Quite Strange, But, there IS a reason for what I am asking You to do..
Take out the Z-80 CPU card out from the Altair, And CAREFULLY Remove the Z-80 CPU IC.. And Place in a safe place, (Location)..
Take the Z-80 CPU Card with the Z-80 CPU Removed and Plug it back into the Altair..
Plug into the Z-80 Card the 8 pin Cable from the Front Panel..
Apply Power to the Altair, Do a Reset and a Stop, then with ALL of the Switches Down (OFF), Press Examine, it Doesn't matter what the Data Leds show..
Next Press, the Deposit Switch and then the Deposit Next, until You have advanced the Address lines about 8 times..
Then Press Stop and Reset, and press Examine..
Your Data Leds should show all Off, anything else and You have a Problem, with the Front Panel.. IF that works, try putting at Address '0000, Data '0000 and at Address '0001 Data '0001, etc up to all eight Addresses..
What You are Doing IS Using Your Front Panel to Write to Memory, WithOut the Z-80 getting in the way..
I tried it on My machine only it was with my 8080 CPU instead of a Z-80 Card, But the Principle would be the same.. And so should the output and the results..
Please let me know what Your results are..

THANK YOU Marty

k1atn
September 21st, 2014, 07:27 PM
I carefully took the Z80 CPU chip out, and put the boards back in (including the memory board) and connected the 8 pin cable to it. I turned it on and WO was lit up and so was every data light and every address light. I tried to do as you instructed i tried to do a Reset and a Stop, then with ALL of the Switches Down i tried to press Examine, then i tried to Press the Deposit Switch and then the Deposit Next, and then Stop and Reset, and tried to press Examine but absolutely nothing happened. The lights stayed the same and NONE of the switches did anything. When i put the CPU chip back in the switches started selecting again.

Marty
September 21st, 2014, 07:51 PM
Hi All;
K1Atn, OK, Good..
Then, let me take a quick peak at the Z-80 Schematic, just to make sure that it should work with Your Board..
But, MOST likely there are/is problems with either the Front panel or the Memory Board..
For Now, let concentrate on the Front Panel.. Also, is the Front Panel "Socketed" or are the Ic's soldered in Directly ??
Go ahead and Take out the Z-80 chips and lets see if We can make anything work..
Check to see If pins 22, (ADDress Disable) 23, (Data Out Disable) and 53 (Sense Switch Disable) on the Altair Buss are all High, If any are Low, the Front Panel will not work..
Go check these and I will look at the Z-80 Schematic..
I checked there should be NO problem, also on the Z-80 Schematic pin 23 Data Out Disable is mis-labeled as pin 21..

Also, Try this, Completely take out the Z-80 CPU Board and turn on the Altair and see IF any of the Switches work, You WON'T be able to have anything of meaning show up on the Data Leds, since they are Disconnected, But, You should see the Address Leds Advance with both Examine Next and Deposit Next.. Then we know it is the Z-80 Board that has an IC that is Causing the Trouble and not the Front Panel..
If You have a Wire-wrap S-100 Board, You could wire in those 8 lines and completely take out the Z-80 Cpu Board, and then use the Front Panel all by itself.. Do You have an S-100 Prototype or Wirewrap Board with nothing on it or You could make it work for our purposes ??

THANK YOU Marty

Marty
September 21st, 2014, 08:28 PM
Hi All;
K1Atn, I JUST REALIZED I MADE A BIG MISTAKE, WHEN I TESTED MY 8080 .. I FORGOT TO PULL OUT THE 8080, AND WHEN I DID LIKE K1ATN SAYS ALL THE LED COME ON AND NOTHING HAPPENS, JUST AS HE SAID..
SO, ALOT OF WHAT I SAID IN MY LAST POST IS NOT CORRECT, FOR NOW.. I WILL LOOK INTO IT MORE TOMORROW.. AND SEE WHAT I CAN DO TO MAKE IT WORK..
I APOLOGIZE, I AM SORRY FOR PUTTING YOU THRU THE EXTRA EFFORT !!!

THANK YOU Marty

k1atn
September 22nd, 2014, 12:22 AM
It's ok Marty, I know you and all the other guys will get me through this :D I will await your response tomorrow.

Marty
September 22nd, 2014, 05:11 AM
Hi All;
K1Atn, Thank You for being so understanding..

But, MOST likely there are/is problems with either the Front panel or the Memory Board..
For Now, let concentrate on the Front Panel..
Also, is the Front Panel "Socketed" or are the Ic's soldered in Directly ??
Also on the Z-80 Schematic pin 23 Data Out Disable is mis-labeled as pin 21..
Going back to my previous post, have You done any of this ??
Now Look at the Questions You posted on Page 5 of this Blog, and the Schematic (page 96) that You posted Earlier, and see IF that Resolves most if not all of Your previous Questions..
If, so, then we can move on Back to the Front Panel again.. and as I stated in that post You need to Really check out the 7405's and make sure they are putting out as they should.. Take the Z-80 Board out, and make the outputs of T and U "high" and "Low" and make sure on the data leds that You see are putting out the proper Response.. Otherwise, You need to make it so that they do and are putting out the correct values.. And work Your way back to the switches themselves.. Once that is done, and we Know that the Front Panel seems to be working correctly, we can move on to the Z-80 Board and the Memory board itself..
THANK YOU Marty

Marty
September 22nd, 2014, 06:51 AM
Hi All;
I just Broke the Data Out Connector on my 8080 CPU Board, its fixable, with a few wires..
I am looking at my various Z-80 Boards, to see what I can use that has the ability to connect into my Data Out connector..
I have an IA 1010 (Ithaca Audio) or a North Star ZPB-A2.. And I have about 4 other Z-80 Boards withOut the connector..
Both the IA and the NS are not working..

THANK YOU Marty

Chuck(G)
September 22nd, 2014, 08:07 AM
I'd have to dig a bit, but I think I have a S.D. Systems Z80 card that has the connector (as a DIP socket, so it requires an adapter) that works just fine.

Marty
September 22nd, 2014, 08:58 AM
Hi All;
Chuck, If it is an SD Z-80 card the it never had a Front Panel connector.. I had one in the Past, I don't have it any more.. So, it must be something else besides an SD Z-80 Board to have that connector.. But Thanks for replying..

THANK YOU Marty

k1atn
September 22nd, 2014, 09:10 AM
IC's "U","X","R","J","T", and "S" are socketed the rest are soldered directly. I will check the 7405's and get back to you.

Marty
September 22nd, 2014, 09:21 AM
Hi All;
K1Atn, OK, It looks like someone has done some work on the Front Panel Before..

THANK YOU Marty

JDallas
September 22nd, 2014, 09:35 AM
...SD Z-80 card the it never had a Front Panel connector...
I pulled out my S.D.Systems boards and visually confirmed that at least the SBC-200 and the SBC-300 neither had that front panel connection. If they once did, it would be on the 1977/76 board set. I'll check my documentation.

UPDATE: The original Z80 board, "Z8800 CPU CARD", sold as S.D.Sales in 1976 (designed by Micronix), was pitched as a board replacement for the Altair and IMSAI. The assembly instructions say, "If you have an Altair, install the white molex connector into the special holes in the upper right hand corner of the Board, A 16 pin socket is provided to the left of the molex connector for IMSAI computers". There may be other mods to use it with an IMSAI.

SDSales Z8800: http://maben.homeip.net/static/S100/sdsystems/cards/SDS%20Z8800%20Z80%20CPU%20Card.pdf

However the manual is among the worst I've seen (at least in English) but they did nicely include a few page tutorial on how to solder. The schematic is incomplete, listing only the S100 connectors and not showing the front panel connectors at all; just a note on the Z80 data lines "front panel".

S.D.System boards on my desk:
SBC-300
VFW-III Prototype
RomDisk (with serial port)
RamDisk
SBC-200 Rev C (two of them)
I/O-8 (8 serial ports)

Marty
September 22nd, 2014, 10:06 AM
Hi All;
I looked at the Z8800 and it Does Definately has the Connector for an Altair Front Panel..
So, Chuck G, may be correct, if it is the later SBC 100 and SBC 200 than they Do not have this connector..
The difference between the SBC 100 and SBC 200 is the speed that the processor is running at..
Thank You J Dallas for straightening me out, I had not seen or heard of the Z8800 before.. I will look at the schematic, later..
THANK YOU Marty

JDallas
September 22nd, 2014, 10:13 AM
...Thank You J Dallas for straightening me out, I had not seen or heard of the Z8800 before.. I will look at the schematic, later...
The Cromemco ZPU board also supports Altair and IMSAI... I've added the URL for the ZPU manuals below. They provide the socket for the IMSAI directly and show how to modify the Altair cable. That might help (I thought you were using a Cromemco... maybe someone else?)

Cromemco ZPU 1977: http://maben.homeip.net/static/S100/cromemco/cards/Cromemco%20ZPU%20Z80%20Central%20Processing%20Unit %20023-0012%201977.pdf

Cromemco ZPU 1978: http://maben.homeip.net/static/S100/cromemco/cards/Cromemco%20ZPU%20Z80%20Central%20Processing%20Unit %20023-0012%20197809.pdf

Cromemco ZPU 1980: http://maben.homeip.net/static/S100/cromemco/cards/Cromemco%20ZPU%20Z80%20Central%20Processing%20Unit %20023-0012%20198001.PDF

Marty
September 22nd, 2014, 11:00 AM
Hi All;
J Dallas, I think I have a Cromemco Z-80 Board, even though I can't find it at the present.. I can't say for sure whether I have it or not anymore..
I do have the Dual 68000/Z-80 Processor Board, and I don't see any place for a connector on it.. And I don't expect one..
See If this Schematic is any better..
http://www.s100computers.com/Popups/PU-Schematic-SDSystems-Z8800-CPU.htm
THANK YOU Marty

MikeS
September 22nd, 2014, 11:20 AM
The Cromemco ZPU board also supports Altair and IMSAI... Yeah, the Z-1 Cromemco system used an IMSAI chassis:

http://www.old-computers.com/museum/photos/Cromemco_Z1_1.jpg

JDallas
September 22nd, 2014, 11:53 AM
See If this Schematic is any better...
Same poor schematic with a undocumented modification penciled in.
My URL goes to the manual and the schematic is the very last page. Not a great piece of drafting.


...the Dual 68000/Z-80 Processor Board...
I'm not surprised S.D.Systems dropped front panel support after that board, I was however surprised that Cromemco supported them so long, must have been a market share they won. My Cromemco ZPU card was included in my Cromemco Z-2 system bought in 1978. Nothing else in that system is Cromemco designed.

I didn't need a front panel because the ZPU jump to a selectable EPROM address on power-up and that was configured to address my Mini-Term MERLIN display EPROM. So when I powered up I got that command monitor and could enter code in hex; a nice simplification.

That MERLIN was a lot of fun... I had the Super Dense Graphics daughter card that gave it a whopping 300x200 B&W graphics pixels! At the time that was the best you could get. After I got a North Star MDS drive, I bought their GWBasic which was impressive.


...the Dual 68000/Z-80 Processor Board...
By the time dual processor boards were being made, the inclusion of a Altair-Imsai panel support would have been unthinkable; that doesn't mean someone didn't do it. We certainly didn't do it at S.D.Systems, if fact we punted on the whole Z80-8088/6 idea after first me, then my boss studied it.

The only Dual processor board S.D.Systems offered was from a foolish acquisition and those cards were a mess - the designer at the acquired company didn't include enough power regulation and heatsinking. I discovered that and our V.P.Engr advised the executive staff who then all voted down the acquisition proposed by the company president.

A week later the president acquired the company anyway. The V.P.Engr quoted the president as justifying it by saying, "Silicon Valley engineers have to be smarter than plain old Dallas engineers. He wasn't so lucky and the computer division was sold a year later. We can only speculate on the reasons. :)

k1atn
September 22nd, 2014, 12:52 PM
Marty, I got your Eprom. How exactly do I ground pin 21, if i'm going to ground it to another IC which other IC would be best and what pin do I ground it to. do i just solder a wire to pin 21 of the Eprom after i bend it out, and then solder the other end of the wire to whatever pin on whatever IC? BTW i haven't checked those 7405's yet but when i do i will get back to you on it.

Marty
September 22nd, 2014, 01:18 PM
Hi All;
K1Atn, Good !
Yes, Bend out pin 21, careful You don't Break it, and attack a Small wire to it, and the other end of the wire to pin 12 of the Eprom.. WithOUT bending out pin 12 and not getting solder on the Part of the pin that goes into the socket..
Wire-Wrap wire works best for this, Wire-wrap wire can be obtained from Radio Shack, If you don'r have any, Black or Blue would be fine if they have it.. As I like to use their Black for ground, and Red for Power and any other color for other things..

THANK YOU Marty

k1atn
September 22nd, 2014, 01:47 PM
i did that, and it's now at least trying to read from the onboard ROM, but MREQ (pin 69 on the bus as stated in the Z80 manual) is not connected to anything on the bus according to my altair manual so it is therefore inactive and according to the Z80 manual, if MREQ is inactive, U9's output will be high, disabling the ROM. when i start up the unit, the ROM led flickers and goes out, and when i turn off the unit it flickers again and goes out.

Marty
September 22nd, 2014, 02:32 PM
Hi All;
K1Atn, Good Progress, when I look at the Schematic (which I am having trouble reading as well), On page 13 of the Manual, it says MReq is pin 65 and is used by Some memory Boards.. And I don't seem to be able to find pin 69 in the manual schematic, could be my bad eyes..
But, there is a Three pin Jumper that is used to attach the Rom U9 pin 12 to the Eprom pin 18.. Try this Completely Remove the Jumper and with Your scope look at in 18 on the Eprom and see IF it goes low, If it does try it and see If You are getting data out from the Eprom.. If not, Temporally attach a wire that is hooked to pin 18 of the Eprom, possibly (if their schematic is correct) the middle pin of the three jumper pins and Ground it, and see IF you get data out of the Eprom..
I Re-looked at the schematic and I saw pin 19 of the Z-80 CPU IC and that goes to two places one is Via a jumper to MREQ pin 65 thru a jumper, that If You followed my earlier instructions the jumper should be taken out.. Look at Your Memory Board and look for pin (Buss) 65 and see If it goes to anything.. It should be nothing, if it is an old memory board..
The other place that pin 19 goes to is MemWRT and that is fine.. So, you should be Ok there..
Also, the other thing to check, on Both Your Z-80 Board and Your Memory Board, is if there is Black Corrosion on the IC leads that are plugged into a Socket, If there is, then You may NOT be getting a good connection.. An INK Erasure will take care of cleaning the pins on the IC's.. Front and Back, not side to side.. I am going thru this on my Ithaca Audio Board right now..

THANK YOU Marty

Marty
September 22nd, 2014, 03:32 PM
Hi All;
After Cleaning the Black Crude from all of the Ic's that had it on them, and bending back in place two bent pins..
And Earlier taking out 4 wired in Jumpers of which I think were put in for a system that didn't have a Front Panel and putting pins in placed were jumpers were Hard wired, so they could be changed..
The Ithaca Audio Board works in my Altair, with the Front Panel..

THANK YOU Marty

k1atn
September 22nd, 2014, 07:14 PM
Glad you got your board working, :) I will try to remove the jumper tomorrow, but I'm not entirely sure which jumper it is. is it labeled? I'm guessing it's the jumper labeled ROM enable?

Marty
September 22nd, 2014, 07:25 PM
Hi All;
K1Atn, "" I'm guessing it's the jumper labeled ROM enable? "" I think so, but to be sure Just Ohm from the Eprom pin 18, to one of the pins for the Jumper.. (You've only got three choices) It should be one of them.. If You are at the correct Jumper..

THANK YOU Marty

k1atn
September 24th, 2014, 07:26 AM
Hi everyone, I will check the jumper and do the other stuff when i can, I have some volunteer work that is taking a lot of my time right now. so i will get back to you all when i can.

Thanks.

Marty
September 24th, 2014, 07:40 AM
Hi All;
K1Atn, Thank You for letting us know.. Good for You that You have some Volunteer work..
I have been on pins and needles, waiting for Your response as to whether anything was working..
So, i'LL just have to be Patient and have some patience..
THANK YOU Marty

k1atn
November 9th, 2014, 09:43 PM
I just thought I'd give an update, but it doesn't look good for right now. I haven't had time to work on the Altair as of late, due to volunteer work becoming work work. So I'll just have to play it by ear for now. I'll let you know when I'm working on it again, but the only thing new with it is possible PS filter capacitors going bad because when i powered it up a few days ago, with a techtroniks 485 oscilloscope attached to the capacitors when i power up the the Altair, the ripple is there for about 2 seconds and then it goes to a gradual but quick flat line with and without the unit under load.

--Jean-Luc--

Marty
November 10th, 2014, 04:03 AM
Hi All;
Jean-Luc, "" due to volunteer work becoming work work. "" Good for You !!!!!!!!!!!!!!!!!!!!!!
I Would Order and Replace the Capacitors before it gets any worse.. Glad You Caught it before it gets worse..
"" I'll let you know when I'm working on it again, "" Please do that..

THANK YOU Marty

k1atn
November 10th, 2014, 06:24 PM
Will do Marty :)

k1atn
February 15th, 2015, 07:32 PM
I double checked my voltages on the bus, and found something interesting. i have the proper voltages for +8A and +8B.....but for the + and - 15v on pin 2 i only have +11.9v and on pin 52 i have -18.4v now if pin 2 requires +15v (and I'm only getting +11.9v) and pin 52 requires -15v (and I'm getting -18.9v) can this be the source of all my problems with getting it to deposit and perform proper functions due to the lack of +15v by about +3v? On the first day of putting the pieces of the Altair back together i had to replace one of the linear transformers to get it to power up. I replaced the 110v transformer with the P/N 102609 in the assembly manual with a RadioShack Transformer with Pri.120v and Sec. 12.6 -0- 12.6 2A Specs. could that transformer be my problem also? do i need to get a different transformer? If so, what liner transformer do you suggest? I know that switching power supplies would be better and safer, but I don't want to go that route at this time. Maybe in the near future but just not right now.

Edit: Well crap!! I tried applying the +15v by an external source (a voltage adjustable switching power supply) I even measured the voltage BEFORE putting it on the terminal block where the +15v connects to it from the PS Board. What i didn't take into account is that the PS Board might be running the +15v THROUGH the diodes, resistors and capacitors BEFORE it comes off the board and onto the terminal block. I'm gonna be honest and admit that I'm still learning about how different circuits work, but I'm pretty sure that what i did was probably pretty stupid, because when i turned the computer on, smoke started coming from what looked like a diode or two so i turned it off quickly and immediately unplugged it from the power strip. Granted I needed to replace all of the diodes, resistors, and capacitors on that board anyway, now i need to do it before i can work on the computer again. :(

k1atn
February 16th, 2015, 01:23 AM
I'll let you know when i've got everything replaced on the board.

Marty
February 16th, 2015, 04:29 AM
Hi All;
K1atn, Welcome Back..
"" . I replaced the 110v transformer with the P/N 102609 in the assembly manual with a RadioShack Transformer with Pri.120v and Sec. 12.6 -0- 12.6 2A Specs. could that transformer be my problem also? do i need to get a different transformer? If so, what liner transformer do you suggest? ""
It all depends on what was there before.. If it was 12.6 then, for now the Amperage would matter..
"" What i didn't take into account is that the PS Board might be running the +15v THROUGH the diodes, resistors and capacitors BEFORE it comes off the board and onto the terminal block. "" Yes, they are used to give the correct output..
"" I'm gonna be honest and admit that I'm still learning about how different circuits work, but I'm pretty sure that what i did was probably pretty stupid, because when i turned the computer on, smoke started coming from what looked like a diode or two so i turned it off quickly and immediately unplugged it from the power strip. Granted I needed to replace all of the diodes, resistors, and capacitors on that board anyway, "" yes, that would be the best course..
"" I'll let you know when i've got everything replaced on the board. "" OK

THANK YOU Marty

k1atn
February 16th, 2015, 07:17 PM
Success!! Somewhat anyway. I cleaned my local RadioShack out of diodes, resistors, and what they had left of capacitors as they were going out of business, and managed to get all 10 diodes, all of the resistors, one 2200mfd capacitor, and i replaced one of the 0.1mfd ceramic capacitors with a 0.01 mfd capacitor. Anyway, i replaced all of those on the PS Board with new ones, and Voila!! The Altair powers up yet again!!!! Unfortunately though, it's still only giving me 11.4v on pin 2. Everything else is fine.

Any suggestions about that low voltage?

Marty
February 17th, 2015, 05:02 AM
Hi All;
K1atn, first, If You have Not done so.. PULL all of the Boards Out of the Machine, and them measure the Voltages..
And see if any of the Boards are or is pulling the voltage down,, Also check ALL of the surrounding pins and make sure that the --18 volts is not leaking to another pin..
Also Double check that the PS board has or is wired correctly..
Check that R4 is Correct, it should have one side to Ground and the other side to --18 volt line, make sure it DOESN'T have one side to --18 volts and the other side to the +18 volt side..
Looking at my Schematic for +18 and --18, the Radio shack Power supply should be OK for the --18 volts..

THANK YOU Marty

k1atn
February 17th, 2015, 12:40 PM
Marty, when i took those voltage measurements, there were no boards plugged in, and no load on the unit. I did check the surrounding pins, and there doesnt seem to be any leakage. as for the PS board being wired correctly, it appears to be. Although i have found that there is an added something that i cant find in the manual attached to the back chassis, with wires going to the place i circled in the manual photo. Also I circled the component that is wired to the spot on the page of the manual i posted. Could it be my problem? Should i cut the wires and remove it? BTW WITH both boards plugged in the voltages measure pin 1 and 51 +8.3v pin 2 gives me 13.8v under load versus 11.4v without the boards in, and pin 52 is -18.4 under load. As for R4 being correct, it appears so.

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Marty
February 17th, 2015, 03:09 PM
Hi All;
K1atn, "" Marty, when i took those voltage measurements, there were no boards plugged in, and no load on the unit. "" Ok..
"" I did check the surrounding pins, and there doesnt seem to be any leakage. "" OK..
"" as for the PS board being wired correctly, it appears to be"" Appears, may not be the same as IS.. Check the --18 Volt Circuit.. IS it the same as what is shown, or not.. "" As for R4 being correct, it appears so. "" Is one side Grounded or not and the other side going to the --18 volt line.. That should be easy to find out with a meter.. If You have a modern meter, just beep it out..
Also, what You are showing is, as near as I can tell a three wire Diode assembly, and the One shown in the Schematic is a four wire Bridge, Big difference.. It could be a Half wave, where You need a full wave.. Which may make a difference in the output voltage Reading 11 volts against 18 volts..
Radio Shack should have Bridge Rectifiers or they can be made with four Diodes..

THANK YOU Marty

k1atn
February 17th, 2015, 04:18 PM
If the R4 you're talking about is resistor 4 then no, I don't think it is hooked up correctly. with the meter it shows a steady 4.6 ohms on the +18v line. When i put my leads on R4 and the -18v line it starts really low and just keeps climbing. As for your comment, "Also, what You are showing is, as near as I can tell a three wire Diode assembly" It actually has 4 wires not 3.

Just so i am sure i know exactly what you are talking about, this is the R4 you're talking about right?

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Also here are better pictures of the component and where it is attached to on the board There are 4 wires and four leads on the component. One wire is attached to each lead.

22809

22810

Marty
February 17th, 2015, 06:00 PM
Hi All;
K1atn, "" Also, what You are showing is, as near as I can tell a three wire Diode assembly" It actually has 4 wires not 3. "" OK, I could not tell from the Previous Photo..
If You have a scope, look at the output from the Diode.. And make sure that the Bridge Diode is truly working in full wave mode..
"" If the R4 you're talking about is resistor 4 then no, I don't think it is hooked up correctly. with the meter it shows a steady 4.6 ohms on the +18v line. "" It should not show anything to the +18 volt line R3, a 4.7K is for the +18 volt line..
(Edit), where you measured 4.7K to the +18 volt side, You are actually measuring R3, because You are on the Ground side of R4 and R3, most likely, so that should be OK, but only If the other side of R4 goes to the --18 volt line..
And just for fun, See, if that end of R4 where it seems to be connected to +18 volt side of things, is in the Wrong hole..
What Does the other end of R4 connect to, the one opposite of where You say is connected to the +18 volt line ??
According to the Schematic that I have, D8 and D10 are connected to C14 on the minus side, C15 and R4.. D7 and D9 go the the plus side of C14 and the other side of C15 and the other end of R4, so they Should all be in Parallel.. Make sure that R4 is in the correct holes for it to be in parallel, with the Diodes and the Caps..
"" When i put my leads on R4 and the -18v line it starts really low and just keeps climbing. "" That is because of the Capacitor, which is charging itself from the voltage of the meter, used to check the resistance of the Resistor.. To keep that from climbing, the Capacitors need to be disconnected from the Resistor.. For, now You need not worry about it..
Just make sure that from one end of R4 it has a direct connection to D8 and D10 and the other end of R4 has a direct connection to D7 and D9, and the same with the two caps..
Also, look at this with a scope and see what kind of an output You have..

THANK YOU Marty

k1atn
February 17th, 2015, 07:58 PM
Interesting. This whole post may sound stupid because certain things have to have a other end to them, but I'm REALLY puzzled now!! What i AM sure of, is that R4 does NOT have a connection with D8, D10, D7, or D9 and i AM sure that One side of R4 is going to D5, and D6, what i can't seem to find is where the other end goes. It seems to go nowhere, i can't find anywhere that is making contact with the other side of R4??? as for D8, D10, D7, and D9 making contact with C14 and C15 they don't, and i can't find where they do. Granted i don't have very good soldering skills, but unless i'm just not making good enough contact, then what i just said above is all i have to report, in which case I have no clue what to do. It was my dad's Altair, and he may have modified it I know that when i got it it was gutted and all it had in it was 4 s-100 slots, the transformers, the PS board (already missing capacitor C12 which still has yet to be replaced) the front panel, and the case. I ALSO know that he swapped the original 8080 cpu board for a z80 cpu board back in the 80's, and he had several other boards in it. Unfortunately like i said, it was gutted and the boards that were in it have yet to be found. I bought a Z80 cpu board and a 4k dynamic ram board for it. I also had to solder wires to it and follow the diagram from the PS board and terminal block pages of the assembly manual to get it to even turn on. The outputs on the oscilloscope will be uploaded soon.

k1atn
February 17th, 2015, 08:35 PM
The videos for what i did with the oscilloscope are on my YouTube page, too many to put in one post the site says. there are 7 in all.


https://www.youtube.com/channel/UCpIt2nT1CeQsHnjGQkss1Hw

Marty
February 18th, 2015, 04:29 AM
Hi All;
K1atn, "" What i AM sure of, is that R4 does NOT have a connection with D8, D10, D7, or D9 and i AM sure that One side of R4 is going to D5, and D6, what i can't seem to find is where the other end goes."" ARE YOU sure that You are Checking R4, That sounds like R3..
"" It seems to go nowhere, i can't find anywhere that is making contact with the other side of R4??? as for D8, D10, D7, and D9 making contact with C14 and C15 they don't, and i can't find where they do. "" What I would suggest is either Take the Power Supply Board out and Trace out the Foil Paths or Turn the Power Supply Board over and Trace out the Foil Paths..
Most likely, the Old Rosin Core solder was not totally cleaned and so You are not making good contact and/or there is corrosion on the Leads and so you are not making good contact, to take a good reading with Your meter..
"" Granted i don't have very good soldering skills, but unless i'm just not making good enough contact, then what i just said above is all i have to report, in which case I have no clue what to do. ""
The other thing to do is to look at the Placement of the Various Parts starting on page 47 of the Power Supply part of the manual, and make sure by following from that page, that each part is in the correct holes and making connection and in the correct direction.. If need be take ALL of the Parts out, and Do it as though it were a new build.. Starting at page 47 and going to page 62, and check that You have the Transformers wired as shown on page 62.. That would be the first place to start, make sure that all of the Transformers are wired as shown.. Then check each section the +8 Volts, then the +18 volts and finally the --18 volts sections.. If need be Draw out Your own schematic and compare it to the one shown by Altair..
It almost sounds like, You have the +18 and the --18 volts mixed up, or else the Diodes are in the Wrong Direction, and so the Voltages are Reversed !!
Also, which Transformer did You Replace, From our talks, I had kind of assumed that it was for the --18 volt section, which I might be Wrong about.. And it could have been the +18 volt section and if that is the case, then Maybe You need to Replace the other Transformer as well..
What voltages are You getting out of the Transformers ?? Maybe that is where we need to start..
You had stated that alot of things were missing When You first "Found" this Altair, So, I would assume that Nothing may be right/correct and go on from there.. Everything needs to be Checked out against the Schematic..
I think at present the Best thing for You to do, is to Treat or Act as if You just got this Machine, and forget what You have done in the Past with and to it.. Start from Scratch..
I Just got out my Step by Step System, (see pictures below..) which has been put away for a couple of Years or so.. And even though I have plenty of Documentation and there are Plenty of wires..
I have to start from scratch and take out ALL of the wires and make NO assumptions about How I think I have it wired.. I have to Treat it, as though I Just got it.. And Rewire it, and check out each piece and make no assumptions.. And assume that I have it wired correctly/right and even IF I trace out every connection, I still could have a mistake in the wiring that no matter how much I think I have checked it, I won't/can't find it, since I am blind to thinking that it is already correct..

22812 22813

THANK YOU Marty

k1atn
February 18th, 2015, 06:11 PM
I followed the manual for putting the components in, and i AM sure i was measuring R4 because it was printed R4 right above it on the board itself.

These are the pages i followed step by step for doing everything i did when putting the Altair back together and hooking it up.

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And this is the transformer i replaced

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Marty
February 18th, 2015, 06:49 PM
Hi All;
K1atn, "" I followed the manual for putting the components in, and i AM sure i was measuring R4 because it was printed R4 right above it on the board itself. "" OK ..

""These are the pages i followed step by step for doing everything i did when putting the Altair back together and hooking it up. "" OK..

"" And this is the transformer i replaced "" I still don't know if that is T1 or T2 or T3, and which voltage it serves..
Also, check to make sure that All of Your Diodes are OK, and doing as a Diode should, passing current only one way..
I may have to hook up my Transformers and take some Voltage checks to compare to what You are showing, If Your Diodes are ALL OK..

THANK YOU Marty

k1atn
February 18th, 2015, 07:25 PM
Yep!! the diodes all check out ok :)

Here are a couple pictures of the transformers. the shiny silver one that says Radio shack is the new one i replaced the old one with. They are in the exact same formation as shown in the assembly manual in way of mounting so i do believe i replaced T2. I replaced T2 with one that says PRI. 120v 60HZ, and on the other side as seen in picture SEC. 12.6v -0- 12.6v 2A
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Marty
February 19th, 2015, 07:19 AM
Hi All;
K1atn, I am not feeling well, so it might be awhile, before I can Rewire the Altair and check the voltages.. Just to let You know..

THANK YOU Marty

k1atn
February 19th, 2015, 11:29 AM
Sure Thing!! :D Get well soon! :)