EEVblog #1308 - 1970's Intel MCS-85 8085 Design Kit!

Will a 1970's era Intel 8085 design kit power up after 40 years?
A look at the Intel MCS-85 System Design Kit and some vintage computer and processor history.

#Intel #Vintage #8bit

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[BigDaddy_MRI]

Definitely the Zilog Z-80. Built a literal ton of controllers with this chip. And I wrote it all in assembly in the Z-80 mode, and used mode 2 interrupts with the CTC, PIO and SIO/0. What a fantastic CPU. Just loved it. And it ran at 4 MHz with no gripes. In fact, I’m designing a GPS disciplined RTC with one RIGHT NOW!! I’m old, and so is the Z-80. But I’m not done yet and neither is that great CPU.

The Z-80 was used in the Heathkit H-89. The video card for that H-89 also used a Z-80 and associated chips for driving the video. I had that H-89 for many years Used to use the Avocet Z-80 assembler/linker/debugger for CP/M with that H-89 and I wrote a LOT of Z-80 code on that machine. It was so reliable, it was amazing. I wish I still had it.

Great video!! Thank you, Dave!!

[hgbugalou]

Honestly as old as this is, it's still a great way for someone to learn how computers work at a fundamental, close to the hardware way.

[opalprestonshirley]

I bought the SDK-85 in 1980, my first computer. Also ordered the Intel 8085 data book which had all of the instruction set and timing diagrams. I learned assembly language on this computer and had many hours of frustration and enjoyment. Thanks for presenting this.

[flymypg]

Why did General Atomics choose the 8085? The simple reason was it had a surprising level of radiation hardness for a commercial microprocessor, hundreds of times better than the Z80, and dozens of times better than the 6502, for about 1% the cost of a "real rad-hard" processor (the 1802 was the only rad-hard game in town back then). It had other benefits, but all were minor or trivial compared to that. I took our systems to our "gamma range" (a linear accelerator) to zap them until they blinked, and it took an impressive level to make that happen. There were several tricks we developed and employed to further enhance its natural immunity, such as reducing the clock from 6 MHz to 5 MHz, and playing with the supplied voltage.

And, yes, the systems were battery-backed with a Gates Gel-Cell lead-acid battery the size of your fist (both fists if you have small hands) that lasted for 5 whole minutes, 300 seconds!

[peterdkay]

I got one back in 1980 for about A$300. I still have the SDK in my museum and it still works.
I expanded it with 4KB EPROM and 4KB RAM.
The 110 default baud rate was used to directly interface with a TELETYPE. This was the ideal interface at the time as you had an input keyboard, a printer and memory storage (paper tape).
I wrote an editor, assembler and EPROM programmer all on this unit.
A typical 1KB program took about 2 hours to assemble (2 pass) and burn an EPROM.
I have loads of happy memories (not)!

[Stefan_Payne]

Blasphemy. AMD Chips on an Intel Developer Board ;-)

[Trenchbroom]

"Hello world" is about the extent of my programming ability, and yet I just adore microcomputer history. Excellent video Dave!

[Tool-Meister]

I joined Intel early 1980. There was a couple of the SDKs laying around the office. Can’t recall the price. This was generally pre-PC days so we sold the incredibly expensive Development System which supported several programming languages and with the optional in-circuit emulator sold for just over $10, 000. Came with two 8” floppy drives!

[onesimpleclik]

I called all those numbers, they've all been disconnected.

[ForViewingOnly]

We were still using the SDK-85 in our microelectronics class in 1989. I was a BASIC programmer on 8-bit home computers in my early teens, and never understood assembly language until I sat down in front of one of these. The SDK-85 really opened my eyes to the workings of a computer.

[toddtempleton]

When you showed the support phone numbers, it really took me back. The 602 area code is for Arizona and at the time covered the entire state. When that technology was manufactured (circa 1980), I was a EE major at Arizona State University and lived just up the road from the Intel factory at Rural Road and Williams Field Road (now Chandler Blvd) in Chandler, AZ where it was made. Many of my EE professors had consulting gigs with Intel, and most of us ended up working on Intel-funded research at some point in school. It is interesting that they used local phone numbers for the support lines instead of toll-free numbers. I never worked on that particular programming kit, but did do a lot of work with Intel processors at the time. Ultimately, I ended up becoming an assembly language developer on the 808x, 80x86, 6502, Z80, 6800, and 68000 processors writing embedded firmware. Now I work for a bank with lots of high-end technology and it is not nearly as much fun.

By the bye, the 121GW is an awesome bit of kit, so thank you for that. If anyone is looking for an excellent, affordable DMM, you'll not go wrong with the 121GW. The videos are just great, so keep up the good work.

[StevenHodder]

When I was doing my Electrical Engineering Technologist Diploma in 1997, one of the courses was industrial control systems and we had that exact board to program 8085s for the lab activities. I remember having to program a servomotor controller using the 8085 and once you got used to the 4x4 keypad it was actually a lot of fun.
The reason why they had the keypad layout as is was so that you had a block of 16 keys for the hex "data" values that were separate from the "command" keys. If you had ABCDEF across the top, you would end up with some of the digits almost completely surrounded by the command keys and a single finger slip could, to quote a Davism, "really ruin your day".

[jimboup]

I have one of these which I rescued out of a rubbish skip from a place where I was working in the 1990's. It powered up but was drawing nearly 2 amps with a blank display and the CPU was getting hot. I put it away and forgot about it for over 15 years. After discovering it again the CPU was replaced and it's working perfectly. I even upgraded the memory and added the bus expansion chips. It's good to show people who only know iPads and PCs what early computing looked and felt like. Great video and enjoyed seeing something I own being eulogised on EEVblog.

[Digital-Dan]

External storage: wire up the TTY interface, connect to a Teletype Model 33 with PTR, enter paper tape, and Sadie's your aunt!

[ericwright]

We used these in college... 1980s.. but since, I bought two of them. Fantastic for what they are... a blast from the past.

[dffabryr]

I had the tremendous chance to work with an Intel 8085 SDK.The one I used was from my boss, so I built my own using wire wrap and a small printed circuit for the display stuff, I still keep my homebrew 8085 SDK !!!. I learned tons of treaks and that practice and knowledge opened me the door to work with far more complex systems until these days. Thank you for this video !!!!

[GrahamNye]

I used one of these at college around 1980. We didn't have many sessions with them but I found even a bit of machine code programming gave me a good idea of what was actually happening inside a computer, compared to our high level language programming classes.

[perhansson]

Your history lesson on these old processors was great, so much info condensed that I had to pause multiple times and go back! Also so many of these old processors still power the world today that many young players would be amazed! The 8085 was released 7 years before I was born, today I work in the industrial field as a service tech repairing these, or to be honest their much younger offspring that is much less reliable and often without schematics as you addressed, so again thank you so much for all of this history, it is nigh impossible to learn it otherwise and get the full picture like this! :)

[savvassidiropoulos]

When I got involved with micro-computers (1981) I went straight to the Z80 camp and quickly learned to program it in assembly. I even wrote a bare bones assembler program in the built-in BASIC of the machine I got (NewBrain, for those who knew it and still remember).
I enjoyed Z80 assembly quite a lot. And later on I did a lot of work requiring speed on 8088 machines as well.
Another CPU of that era that I did some work was the NS COP402 - which was considered a 4 bit micro-controller.

[kevincameron]

Cool! I did a couple of projects on these back in college. I spent hundreds of hours wire-wrapping circuits and punching in programs. Thanks for the blast from the past, Dave!