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smp
December 23rd, 2015, 07:26 AM
Hello all,

I have been intrigued by a couple of eBay auctions:

The first one:
http://www.ebay.com/itm/191765141319?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

The second one:
http://www.ebay.com/itm/252218142611?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

As you can see, these two Altair Turnkey systems have different boards in them:

The first one:
MITS 8800B CPU BD REV 0
ALTAIR 8800B TURNKEY MODULE REV 0
MITS 16K RAM (?)

The second one:
MITS 8800B CPU BD REV 0
PCC TURNKEY MODULE
PCC S-100 INTERFACE
CEPC 4-SIO-1

I can see that the first one has a memory board but no I/O board, and the second one has no memory board but it does have an I/O board. And, of course, the second one has the power switch key, but it is indicated that it is not the proper one for this system.

The bulk of my experience with S-100 systems is with IMSAI systems. Can anyone please tell me what were the original boards that would have been in a stock Altair 8800B Turnkey system? Was it like the original Altair 8800 kit, where you got only the CPU board and the front panel? Would it have been only the CPU board and the Turnkey board? Then the buyer would have had to add memory and I/O?

Is the first one actually incomplete because it does not have the PCC S-100 Interface board? I am not familiar with this board. Is it a required board for the system to run?

Any assistance and/or advice that you may have to offer would be appreciated.

smp

Marty
December 23rd, 2015, 07:42 AM
Hi All;

SMP, I never had a TurnKey, But I did have an 8800b, and I could choose what was included with it, above the Basic System..
Which I/O, How much Memory, etc..
Which I/O depended on two things,
1. What kind of a Terminal I had, Teletype, vs, Video Monitor (Glass Teletype)..
2. What I was using for Storage Input, Paper Tape or Cassette..
And of course How much Memory I could afford..

I don't know if this Helps or not..

THANK YOU Marty

deramp5113
December 23rd, 2015, 08:27 AM
Most Turnkey systems were geared towards the business user. In addition to the required CPU and Turnkey boards, they typically included 48K-64K of RAM and a disk controller.

System 1:

The first system you list has the older Rev 0 version of the Turnkey board. You can tell this by the presence of 1K of RAM on the board (8 chips above the EPROM sockets). The Rev 0 board included the 1K of RAM for use by the Turnkey monitor ROM. Unless the 88-CLG mod is made to this board, the Rev 0 board does not have the ability to disable its own ROM address space to allow use of a a full 64K of RAM (see Rev 1 Turnkey board below).

The Turnkey board includes one 6850 UART which is typically at I/O address 10h and then looks just like the 1st port on an 88-2SIO. The header on the right side of the board goes to the DB-25 connector in the rear panel. The header on the left side of the board connects to the front panel board.

System 2:

The second system you show has the Rev 1 version of the Turnkey board. This version has no on-board RAM and disables the ROM address space whenever an IN instruction from the sense switches (of 0FEh for that matter) is done. This allows use of a full 64K of RAM once the system is booted. I'm not familiar with the CEPC board, but it looks like it supports up to 4 serial ports with the 6850 UARTs. These ports would be compatible with the standard 88-2SIO ports expected by most Altair software.

The PCC S-100 interface board connects an Altair computer to a Pertec/iCom 3812 dual-drive (8 inch) cabinet. This cabinet looked almost identical to the MITS 3202 dual drive cabinet, but instead of using the dual-board disk controller in the Altair computer, the controller was actually in the drive cabinet. The board in the Altair was just an interface for passing data between the Altair and the controller. The interface board also included the boot ROM. This configuration is completely incompatible with "normal" Altair 8" software and floppies. Instead, it was used to run FDOS-III and DEBBI (disk exended BASIC by iCOM).

Finally, the PROM sockets on both Turnkey boards are used for 1702A EPROMS containing, for example, the Altair disk boot loader (technically not needed in system #2 if used with a 3812 drive), and the Turnkey monitor.

Mike

glitch
December 23rd, 2015, 08:28 AM
A basic turnkey would include:

* MITS CPU board
* MITS Turnkey module (this provides the serial console, too)
* One or more MITS 16K static RAM board (using SEMI4200s)

The turnkey 8800b systems have more potential to be a "pure MITS" machine, since MITS had enough of their own board offerings to ship them that way. I'm not sure what the minimal order-able offering was, but having gone through a number of turnkey systems, they seem to mostly use the above components as the base system.

One "fun fact" about that base configuration: you can only use an 8080 based CPU board with the 16K SEMI4200 based RAM boards, and only some 8080 CPU boards will work with the Turnkey module's power-on-reset circuitry. You're pretty much stuck with the turnkey module, as it handles power-on-reset when the power key is turned, and also interfaces with the LEDs and switches on the front panel.

billdeg
December 23rd, 2015, 09:07 AM
Hello all,

I have been intrigued by a couple of eBay auctions:

The first one:
http://www.ebay.com/itm/191765141319?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT



This one's turnkey board is missing the Turnkey ROM, but otherwise this is the minimum/complete turnkey system. I doubt this one was tested unless seller put in a turnkey rom and for some reason removed it. NOTE: The MITS Tunkey board is also the I/O board. The PCC SIO board as an extra board for unknown purpose, poss printer or ??



The second one:
http://www.ebay.com/itm/252218142611?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT



Missing RAM, but any late 70's RAM would be OK if it has phantom control like a Tanner RAM board.



Is the first one actually incomplete because it does not have the PCC S-100 Interface board? I am not familiar with this board.



No, it's complete. PCC is the name of the company who bought MITS. [REMOVED COMMENT - not true]

Probably neither of these will work out of the box, but I'd get the 2nd machine if it was cheaper. $1500 is too much. $999 for the 1st machine plus whatever time you will have to spend to fix it is kind of pricy for me given I have gotten these cheaper in the past, but a fully working Turnkey is going to cost $2000.

NOTE: My original comments were waaay off, so I edited this post. Sorry I was totally wrong due to misreading.
Bill

glitch
December 23rd, 2015, 09:37 AM
I would expect it to be a project.

For sure!

billdeg
December 23rd, 2015, 09:54 AM
Note I corrected my earlier comments. The 2nd machine has at least one other I/O board (the PCC board) which might be for printing. The board in the back is prob a multipurpose I/O board. So, with the original turnkey board I/O (for terminal) there are many things you can plug it into.

Worth $1500? Not sure. I'd bargain down a few hundred or request a power supply test.

deramp5113
December 23rd, 2015, 10:25 AM
Bill,


The 2nd machine has at least one other I/O board (the PCC board) which might be for printing. The board in the back is prob a multipurpose I/O board. So, with the original turnkey board I/O (for terminal) there are many things you can plug it into.

The PCC S-100 board is an interface to the FD3812 dual-drive cabinet and controller. The controller is in the drive cabinet itself, the S-100 board is used to transfer data from the Altair to the controller. The S-100 board also includes the boot ROM. Here are some pictures:

28482 28483

The board in the back is a four port serial I/O board that uses 6850 UARTs as present on the 88-2SIO and the Turnkey module (i.e, it's compatible with most Altair software). This particular board has 2 of 4 ports populated.


Missing RAM, but any late 70's RAM would be OK if it has phantom control like a Tanner RAM board.

Actually you don't need phantom on the RAM board as MITS hardware did not use phantom. Instead, the Turnkey board overdrives the MREAD signal on the bus with multiple gates in parallel (or a transistor on early boards) so that the MREAD signal from the CPU is never seen by system RAM.

Mike

billdeg
December 23rd, 2015, 11:29 AM
thanks for the clarification. I

smp
December 23rd, 2015, 12:15 PM
Marty, deramp5113, glitch, billdeg,

Thanks very much for your informative replies. I greatly appreciate the information you've provided. I had no previous knowledge about the PCC S-100 Interface at all, and I was uncertain about the original minimum configuration of the system.

I also appreciate the comments about the potential condition and value of the system. I would clearly lean towards the $999, but, if I try to go for it, I may attempt to contact the Seller separately to see if I might be able to get a bit off that price.

Here's another question: Since I've spent a bit of time bringing up both the single density and the double density Northstar floppy disk controllers in my IMSAI system, is there any reason that either of these floppy disk controllers might not work in the Turnkey Altair? I realize that I need to get some sort of system monitor program into an EPROM and onto the Turnkey Board. I am assuming that the system would then power up into the system monitor, and I could issue the boot command for the Northstar floppy disk controller from there.

You may be getting the feeling that I am very used to my switches-and-lights front panel on my IMSAI - and you are correct!

Thanks again for all your attention and assistance.

smp

deramp5113
December 23rd, 2015, 12:33 PM
That'll work fine. I've had both North Star controllers working in Altair computers. I also have CP/M for the North Star patched for Altair console I/O (e.g., 2SIO port at 10h) if you ever need it.

You can set the Turnkey board to auto-jump to E800 or E900 for the DD or SD controller respectively. You'll need to be sure and put the ROM (and RAM if you have the older turnkey board) above EC00 so they don't conflict with the controller.

Mike

glitch
December 23rd, 2015, 01:11 PM
By default, the older turnkey boards put the RAM and ROM in the top 4K of address space (0xF000 to 0xFFFF), so you shouldn't conflict with the North Star controller if you follow that setup. Aside from the Turnkey monitor (TURMON), Bill Degnan and I have copies of an earlyish (2.0? 3.0?) version of the Vector Graphic monitor already patched for the Turnkey board's serial console. You could probably add another command to the Vector Graphic monitor for disk booting with the North Star controller -- I patched the Dajen SCI monitor for disk booting off a North Star single-density controller.

smp
December 23rd, 2015, 01:26 PM
deramp5113 and glitch,

Again, thanks very much for your replies.

Contrary to what I said before, I've put in a "best offer" for the system without any memory. I don't expect that the Seller will have a chance to see it and respond before the auction ends, but you never know. I also have no idea if there have been any other offers, so I could not be the best in that case.

Thanks again. You folks have been a great help.

smp

glitch
December 23rd, 2015, 01:44 PM
In my opinion, you're better off with a non-MITS RAM board anyway. Unless you're going for a "pure MITS" system. The MITS 16K static boards were their best RAM board, and still not great.

smp
December 24th, 2015, 10:32 AM
Contrary to what I said before, I've put in a "best offer" for the system without any memory.

So the original auction ended without any interaction on my offer, as I expected. Apparently, the auction was automatically re-listed.

I've been in communication with the Seller and we are currently haggling with offer-counteroffer.

I fully realize that the value of any given system rests with the buyer, but I would like your opinions, if you would. In *your* opinion, is this system worth $1000?

http://www.ebay.com/itm/252223829166?_trksid=p2060353.m2763.l2649&ssPageName=STRK%3AMEBIDX%3AIT

It appears to be in pretty good condition. It also appears to be a factory-assembled system. What do you think? I'm concerned that this Seller has never done anything with the system except possess it. Given this equipment, are there likely to be a lot of issues with it? What do you think?

Thanks very much, in advance, for your responses - positive or negative.

smp

glitch
December 24th, 2015, 11:24 AM
It almost certainly won't work without some repair work. At the minimum, you're going to want to reform the caps in the power supply. So far I think I'm 0 for 0 on working MITS boards. They look like they are in good physical condition though, so it's certainly repairable. Plan on spending some quality time with the multimeter and logic probe.

With the way prices have been going on MITS stuff, $1K is probably about what it's worth.

smp
December 24th, 2015, 01:44 PM
Glitch, thanks very much, once again, for your attention and response.

I've decided to decline this one. Aside from the Altair panache, I would not be acquiring any more capability that I have now with my IMSAI and the other front panel-less Integrand S-100 chassis that I have.

Thanks again to you all who responded with your thoughts and advice.

smp

glitch
December 24th, 2015, 02:39 PM
I've decided to decline this one. Aside from the Altair panache, I would not be acquiring any more capability that I have now with my IMSAI and the other front panel-less Integrand S-100 chassis that I have.

The Optima chassis is kinda nice, I think that's probably the best feature of any S100 Altair though. Definitely prefer my IMSAI overall.