View Full Version : MCS-80 System Design Kit -- Need documentation

John Schulien
March 21st, 2015, 06:01 AM
Greetings! I have in my collection an MCS-80 System Design Kit 8080 development board. It's obviously nonfunctional as there are empty sockets and solder residue from where some chips were desoldered. I'd like to get it working again, but I'm having trouble finding documentation. If this were a SDK-85, I would be in better shape as those manuals are on bitsavers, but I've scoured the net and have been unable to find the assembly and operation manuals for this kit. I did find a 1977 Electronics (Australia) magazine article PDF with a little information on the board. From this I learn that the development board originally came with a set of manuals:

8080 Users Manual
8080 Assembly Programming Manual
Kit instructions
Kit user's guide
8080 Reference card
"other material"

So far I have been able to find copies of:

MCS-80/85 Family User's Manual
8080/8085 Asseembly Language Programming

The former has some information on the SDK-85 board, but nothing on the SDK-80.

Can anyone help me find the SDK-80 specific assembly instructions and user's guide?

Thank you, JOhn

March 24th, 2015, 10:02 AM
Mustafa Katie doesn't list this as one of the books in his archives - but he has a you tube video (https://www.youtube.com/watch?v=KFOs-gxR7qA) showing his reconstruction of the schematic and PCB board. If you could get a copy of those, it should help out.

John Schulien
March 28th, 2015, 09:57 AM
Thanks. I've sent a contact request to Mr. Katie on facebook. Hopefully that will get me in touch with him.

Since I seem to be the first person to bring one of these boards up on this forum, I'll post my progress here. Here is what I'm starting with:


Unfortunately the three key chips -- the 8080, 8224 and 8228 are missing, which is a real shame, because they were probably ceramic/gold 1975 originals. The 8251, 8255 and 8708 seem to be original. 3 of the chips have 1975 date codes. One of the chips has a 1993 date code, which indicates to me that someone made some later effort to get it working again.

I originally thought that the two 8212 chips or sockets had been desoldered, but on closer inspection, each socket has 8 jumpers soldered in, bypassing the address buffer chips.

The previous owner filled up the RAM sockets with Intel 2111 chips (256 x 4), so the board is maxed out with 1K of RAM. The EPROM is not in the first socket, where I would expect to find it, and it has a non-original sticker covering the window. It would be very nice if the EPROM still had the original monitor program, but I suspect this is not the case.

So far I have purchased a small switching power supply, two 8212 chips, and I've ordered 8080A, 8224 and 8228 chips off of ebay. Apparently ceramic and gold 8080s are pricy collectors items now. I've been led to believe that the 8080A will work properly in place of the 8080, so that's what I'm planning to go with. If I can get it working I'll consider looking for period-correct chips.

I'm mulling how I'm going to analyze this board and bring it up. There are a fair number of complications. The right hand serial port seems to be connected, but the signals pass through a lot of jumper options that I don't have any information on. There also seems to be a jumper bank for EPROM address selection, which I have no documentation on. This is where my documentation deficit is working against me. I don't know if this board was working when the key chips were removed.

I feel that the first step should be to obtain an EPROM programmer that can read and write 8708 chips. That would let me read the existing EPROM to see what it contains and write a short program to run a short loop. I have a USB logic analyzer so that would allow me to examine the bus and confirm that it the processor is operating correctly. Then I would move on to the serial port and hopefully bring up the monitor.

Any ideas or pointers to resources would be appreciated. Thanks - John

April 3rd, 2015, 01:10 PM
"Dave's Old Computers" has a photo of the SDK User's Guide (http://classiccmp.org/dunfield/other/h/mcs80bks.jpg) - you can try contacting him to get some more information. Apparently he actually runs his old computers periodically. Makes me envious!

John Schulien
April 5th, 2015, 08:03 AM
Thanks. I emailed him.

(I'll be quite delighted when the forum software decides to stop auto-moderating my requests, BTW.)

John Schulien
April 5th, 2015, 08:09 AM
By the way, when I do get this working it will be an international effort. Thanks to ebay, I'm combining an 8224 sent from Oklahoma, an 8228 sent from China and an 8080 sent from Ireland. And those were the cheapest prices including shipping!

April 5th, 2015, 04:50 PM
I have the ePROM dump of the 8080 monito. on my website. See also retrotechnology.com pages on this machine and/or similar.

April 6th, 2015, 02:54 PM
I have the specific manuals you have also but I also have an early document that talks about the MCS-80. The document is entitled: "Intel 8080 - Single Chip Eight-bit Parallel Central Processing Unit - April 1974" and you can download it here: http://vintagecomputer.ca/download/intel/Intel%208080%20-%20Single%20Chip%20Eight-bit%20Parallel%20Central%20Processing%20Unit%20-%20April%201974.pdf

I'm not sure it will help but it will give you some more info.

John Schulien
April 6th, 2015, 04:06 PM
Thanks Bill. That's great information. The 1977 article/review gives some specifics on the original monitor. The original monitor is only 1K. When you bring it up it is supposed to display the message "MCS-80 KIT." The prompt is a period, and there are only 6 commands -- D to display memory, M to move blocks, S to change a memory location, I to insert hex data, X to examine registers and G to run your code. So it's probably a stripped down version of one of the monitors you have on your site. I might use the SSM monitor if my EPROM doesn't contain the original monitor and I can't find it. That one is only 2K and seems to be the closest in spirit to the one that's supposed to be there.

snuci -- thanks. I didn't have that one yet. My PDF folder and reading list is growing.

May 16th, 2015, 09:05 AM
Hi John,

if you want the 1k Monitor Source for the "SDK80/MCS80KIT" i'll send it as a ZIP-File, please give me an PM.
I have an unassembled Board but unfortunately i did not have the "MCS-80 System Design Kit User's Guide"
I've also wrote to Dave Dunfield to get an copy of the User Guide, he is not willing to do it for free.
If you get a copy of the Manual i'm intersted in it.
The "SDK-80/MCS-80 KIT" was the first Microcomputer i worked with in 1976.
So if you have some Questions, perhaps i can answer it.

July 15th, 2015, 10:21 AM
Hi Walter, I'm also interested in the 1K monitor for inclusion in MAME. I've just submitted a driver for the SDK-80 with a 4K BASIC, having the original monitor would help define the original kit.

Any way you can contact me as I don't yet have PM?

July 15th, 2015, 09:04 PM
Strange, I thought I had the scan of my SDK-80 manual on my website and wondered why google didn't find it for you, but... looks like I don't have it up.

Lemme put the jpgs together into a pdf.


July 15th, 2015, 09:18 PM
OK, it's early morning here which maybe explains things. I thought I'd replied to this thread but can't find the post.

Anyway, I thought it strange that google didn't point you at my website, since I thought I'd uploaded the manual there. Turns out I did but I never linked to it so google couldn't find it.


The User's Guide contains a listing for the monitor, if someone wants to type it in. My SDK-80 is in storage somewhere and even if I find it my EXPRO won't read 2708s I don't think.

July 17th, 2015, 07:42 AM
Thanks for the guide with the monitor listing. Really hope to get a reply from Walter otherwise I'll be typing it in.

On your site you mention you have Tiny Basic in 2 ROMs, I see a link to the source there, do you have actual dumps too? The version I currently have is 4K whereas yours suggests 2K.

July 18th, 2015, 06:16 PM

July 19th, 2015, 12:09 AM
When I was much younger I plugged the two ROMs into my 6800D2 and copied some of the contents down. But not all of it I'm afraid. Or maybe I did copy it all but some pages were lost. This was back in the eighties.

Going through stuff much more recently I scanned the two pages I found. It's the first 256 bytes and the second ROM, looks like. You're welcome to it, errors and all.


I checked my DOS box and EXPRO does not support the 2708 so this will have to do for now I'm afraid.

July 19th, 2015, 02:32 PM
In the ZIP-File you will find the Source Code !