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Marty
September 23rd, 2014, 06:03 AM
Hi All;

I have the Monahan-Lynch Z-80 Board and it seems to work fine.. Thank You to John for His Help..
But, I am wondering, Why it won't Run with a 8 MHZ Oscillator ?? It Runs fine with a 2 MHZ, a 4MHZ and a 6 MHZ..
Is the Z-80B, only good up to 6 MHZ, and I need a Faster Z-80 like a Z-80C ??
Or is is something else that seems to be keeping it from Running at the higher speed ??
I have put "F" and "AS" IC's, where John recommends I switch to something faster than an LS..

THANK YOU Marty

Marty
September 23rd, 2014, 06:36 AM
Hi All;
Just after posting this question, I did a Search, and looked a Jameco and Mouser, and the Answer seems to be, that I need a Higher speed Z-80.. As there is an 8MHZ and a 10MHZ variation..
I wonder what the inside difference is ??
I would still like any input anyone can give..

THANK YOU Marty

gslick
September 23rd, 2014, 07:47 AM
Zilog has Z80 versions rated up to at least 20MHz, which is the Z84C0020 version.

I bought some Z84C0020PEC off of eBay for a project. $16 total shipped for 10 of them. (Haven't verified that they are all good at that speed yet...)
http://www.ebay.com/itm/181055692734

Ragooman
September 23rd, 2014, 08:31 AM
wait that's $15 for 10pcs ??
that's hard to believe
I would like to hear your test results

Mouser has them too, but for $10ea - price break is at 25 for $8ea
They are currently out of stock
But you can see they have more ordered, delivery data is 10/3/14 for 111pcs.
I guess they don't like to stock large quantities
But at least you can rely on Mouser and it doesn't take a month to deliver
Mouser Part #: 692-Z84C0020PEG [PDIP-40]
http://www.mouser.com/ProductDetail/ZiLOG/Z84C0020PEG/?qs=sGAEpiMZZMvu0Nwh4cA1wSr8HV81hI8hiPObc28THq4%3d

Marty
September 23rd, 2014, 08:32 AM
Hi All;
As soon as I can afford it I am going to get two z-80's 8MHZ, and two 10MHZ, and four Pio's for 6MHZ if they make them otherwise 4MHZ..
We'll see if my Altair Buss can support 8 MHZ, I doubt 10 MHZ..

THANK YOU Marty

JDallas
September 23rd, 2014, 11:14 AM
...We'll see if my Altair Buss can support 8 MHZ, I doubt 10 MHZ...
Overclocking a z80 system is likely to create chaos in your system.

The designer checked that all the I/O, Memory, wait states, buss access latency worked at the processor clock listed. When you overclock, you're on your own. The misreads can be insidious because if you misread an opcode now and then, you may do a lot more damage to your files before you know it.

Usually, i.e. not in a Vintage scenario, a system is designed and spec'd for the fastest speed that is feasible. Because this is a S100 board for the Altair, that's not necessary applicable because it may have just been made 6Mhz because others have done that in the past.

Do yourself a favor and just write Monahan and ask him if his design will run at 8Mhz or beyond. If it can run fine at 8Mhz, he'll likely sell that option.

As to the rest of the system, you'll have to pull the schematics and figure it out yourself.

If you want a 20Mhz Z80 S-100 system, buy one designed for that speed.

Marty
September 23rd, 2014, 11:28 AM
Hi All;
Thank You, JDallas, for Your answer..
John has Run His System at 10 Mhz reliably, and mine work just fine at 6 MHZ..
But Partially because of problems that I had been having with the ZFDC Board, I had thought, (Wrongly) that the Higher speed would Help it.. I have Mostly fixed that Situation..
And the Other Reason Is to see What Speeds My Altair will Reliably Support.. And I an Happy at 6 MHZ and would not think of Running it at 20 MHZ.. Most like I will be Running it at 4 MHZ, I need to find out which speed works the best with the ZFDC Board, once I get it working, as it should best communicate with the Host Z-80 system..
"" If you want a 20Mhz Z80 S-100 system, buy one designed for that speed. "" I Never said I wanted to Run at that speed..

THANK YOU Marty

Frank S
September 23rd, 2014, 11:36 AM
Hello Marty,
By the way, do you have a backplane with active termination?
Frank

Marty
September 23rd, 2014, 12:09 PM
Hi All;
Thank You Frank, for Your interest/question..
At Present No I do not, which is Part of the Reason for My wanting to know what is my upper speed limit..
I know that John said in His Article for Bringing up the Z-80 that at the Higher speeds the System need will need it..
I do have an Extender Board that Has Termination on it and I have Yet to see If it is in working order, It has some Regulators and Transistors on it.. And at present, I don't know what works and what doesn't work.. I don't know If it is active or not..

THANK YOU Marty

Tor
September 23rd, 2014, 10:34 PM
wait that's $15 for 10pcs ??
Or you could buy 100 from the same source, for $114.. :)

I think I'll go for the '5pcs' deal, which isn't bad either.

-Tor

Ragooman
September 24th, 2014, 06:02 AM
Or you could buy 100 from the same source, for $114.. :)

I think I'll go for the '5pcs' deal, which isn't bad either.

-Tor

it's just an incredible price
I realize there are many good items over there available at cut-rate prices
But I really haven't noticed the vintage components being offered by those places.
I like to know if they are not fake - cause that's a recurring issue.

I got burned on some LM7805 [TO-3] - they were all fakes - never had +5v output.
I took some apart and the die looked vastly different under a microscope - starting with the size.
But without a electron-microscope or xray, I can't look deeper into the problem.
The xray at work is only good for pcb's
gslick mentioned he still has to test the Z80's he just bought.

Marty
September 24th, 2014, 06:46 AM
Hi All;
I'LL stick with Mouser..

THANK YOU Marty

Marty
October 2nd, 2014, 02:07 PM
Hi All;
I got in my 8 MHZ Z-80's, and it works fine on my Altair..
I also, today found my problem I was having on my ZFDC Board..
When typing in "qi11" it would Output the Wrong thing.. I typed in some other addresses, and found a pattern..
Since I could Download I was almost positive it wasn't my Z-80 Board any more..
Following my Pattern caused me to look at what I had in the Machine, maybe I had something wrong, and I did..
After, I saw it, I instantly knew what it was..
I am using my I/O Serial Card that is for the Altair, and I had modified it, as Per Grant Stockly's instructions to be able to use it as a Dual port I/O.. And so it would respond to both '00 and '10 .. And Port '10 is one of the ports where the ZFDC communicates with the Rest of the System.. And so Both Boards would respond for ports 10 and 11 and 12 and 13..
Once I got that fixed it works well, now..
Since I had made the modification over two years ago, I had forgotten about it..

THANK YOU Marty

Marty
October 3rd, 2014, 08:42 AM
Hi All;
My ZFDC Board, Now Works !!
I have had it working with 51/4 and 8" Drives..

THANK YOU Marty