Reviving The Intel SDK-85

In 2022, I received an incredible gift from my father-in-law for my birthday: the Intel SDK-85. It is an awesome piece of historic computing hardware, complete with English documentation. He even included the Dutch documentation regarding the system and the student materials from his studies, where he had to use this very system with his best friend. This barebone system has a rich position, both in computer history and in the life of my father-in-law, which means there is only one thing for me to do...

Give it the love it rightfully deserves!

Background

Now, before I dive into the personal history of this system, I think it's good to explain what the Intel SDK-85 actually is. Lets travel back in time to the roaring 70s

Intel SIM8-01, one of the first SDKs by James007Brown, CC BY-SA 4.0 via Wikimedia Commons

when Processor development for the consumer market skyrocketed. Whenever Intel would release a new model CPU, they would release a System Design Kit alongside it with the same processor. The idea behind the SDK was to allow engineers, students and researchers to play with the new processor to get more familiar with the technical capabilities. These SDKs were barebone PCBs with a complete set of chips, capacitors, resistors, and more to build a fully functional computer. All you had to do, was soldering everything on the PCB and give it some juice to bring it to life. The PCB also included a breadboard part where you can solder extra components into the circuit to expand the computer to interface with other hardware, as done in this research paper.

Personal History

The hardware my father-in-law gifted to me has a large sentimental value. In late 2021 or early 2022, during the renovations of mine and Hubbs' first home where his dad helped us out a lot, we were chatting about old computer hardware. That is when my father-in-law's story of the Intel SDK-85 came up...

It was the late 70s, and my best friend and I had to buy a computer system for our coursework. We got it on a Friday and within the same evening we had it all soldered up an booting. Of course, we were students, and you know whats most important to us 20-something year olds: Beer! So, we had set out to make the little 6-digit screen say "Bier is op" (this is Dutch for "Beer is gone"). It took us the entire weekend programming in Assembly and debugging the program, but by the end of it we got it working.
— My Father-in-Law

Unable to recall what computer system precisely he had worked with that time, my father-in-law called his best friend to ask since he still had the system laying around. It was the Intel SDK-85. Later that year, his best friend gifted my father-in-law the system including documentation and coursework for his birthday, since he had asked about the system. That was my first time seeing it, and boy, did I get excited about it. I had a fun discussion with them about their "Bier is op"-adventures, also saying that I'd love to take on that challenge one day because I wanted to learn Assemby. The next year, this year at time of writing in 2023, my father-in-law passed the system on to me with the same challenge: Bier is op!

Going Forward

There is a fair bit I'll have to get done before I'm even thinking of booting the system, let alone start programming and toying with it. Remember, this system was built sometime between 1976 and 1979. At that age, there is a fair chance that the capacitors on the board could be leaking which can make the system go BIEM and beyond repair. Think of it as double checking the engine of an old-timer car you just bought before starting it and going for a spin.

Parts List for the Intel SDK-85 from the Dutch Building Manual

After changing the components on the board, I can finally take the Intel SDK-85 for a spin. Which means, I can start the challenge my father-in-law has given me. One thing is certain, the Dutch language in its full colourfulness will echo through my little office as I'll be writing Assembly code and debugging it. But I'm confident that I can make the little display say "Bier is op" and once that's done, I'm off to learning more Assembly and toying around with this awesome board!

Project Code Name

Belladonna

Compontents

Intel SDK 85

Processor

Intel 8085

Major Tasks

Replacing Capacitors and Resistors

Getting it running

Program Assembly

BIER IS OP!

Have Fun!

Below, you will find the articles I've written on this project so far.

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