Microcomputer Design Projects 1

[ElMicha]

Hey all, could I get some recommended design projects and textbooks to learn how to build my own microcomputers? I've read the "Digital Logic and Microcomputer Design" textbook already for a course in uni but I want to go more in depth.

 

[IRstuff]

Few actually go that route, since building a decent motherboard for a competitive computer is nontrivial. Building just a non-state-of-the-art computer is probably more doable. There appears to tons of examples for such on the web

https://mikelyons.org/2021/02/21/how-to-design-a-motherboard-for-your-project-part-1

might be a starting point.

https://en.wikipedia.org/wiki/Build_Your_Own_Z80_Computer

TTFN (ta ta for now)
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[3DDave]

There's a YouTube channel devoted to that for the 6502. Ben Eater

https://www.youtube.com/@BenEater/videos

he also sells a kit of parts, all off the shelf if you want to get them yourself. His website also has links to those videos

https://eater.net/

The price for the 6502 kit is about $90 - which is not much more than the list prices for all the parts and makes up for the time to find them.

He also has a kit for just under $300 that builds an 8-bit computer from basic logic chips, if you want to understand how the internals of a CPU works.

There are online 6502 emulators

http://www.6502.org/tools/emu/

One more general source of info is righto.com, where Ken Shirriff does reverse engineering and analysis on individual logic chips up to entire computers. He's done several of late on how the 8086 processor functions. He examines the physical structure of the chips as well as the logic the chips use.

 

[davidbeach]

Kinda so 45 years ago…

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[IRstuff]

Kinda so 45 years ago…

Exactly, low clock rate makes it easier to get something running with poor PCB and lower quality components. Making a 2 GHz processor run without problems isn't a trivial thing for a newbie.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[dik]

I remember the days of the 8088 and the 286, and doing timing loops in my programs to determine the fastest way... also doing sub-programs in assembly to speed up parts... it was a different time.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[ElMicha]

Sounds like this is going to be a painful journey. I'm excited! thanks for the input and recommendations guys.

 

[IRstuff]

It's not necessarily painful, but likely long, particularly if you haven't any solid background in digital circuit design/build, including PCB layout/design.

I would recommend starting REALLY SMALL. While digital circuits are ostensibly all about ones and zeros, the physical world is analog, and there are noise issues, power supply noise, circuit thresholds, etc., etc. One should particularly note that the Z80 and 8086 generation of digital chips and most of what you might have learned in class was based on 5V TTL/NMOS/CMOS logic, i.e., 5 volt DC powered, while current hobbyist and some commercial circuits run on 3.2 V DC, or lower voltages. The Z80/8086 were design using integrated circuit technology with single digits of microns MOS gate dimensions, with tens of thousands of logic gates, while something like the Ryzen 7 processor on the laptop I'm using now has gate dimensions on the order of single digits of nanometers, and consequently, multimillions to billions of logic gates. The smaller gate dimensions require much lower operating voltages to prevent circuit damage and malfunctions; internals of such microprocessors are running below 1.5V DC, but power dissipation is around 45-65W, which means a minimum of around 30 AMPS of supply current. Designing a motherboard to handle the supply current and GHz clock rates and noise is not for a newbie.

The 6502 project 3DDave mentioned above is probably a safe design project and has a very storied history, since that was the scale of the Apollo space mission navigation computer and was the processor used in the Apple II. Alternately, the Z80 processor might also be a practical project, since the IBM PC can trace its operating system design to the CPM operating system that was used for the early Z80-based personal computers.

https://maker.pro/pic/projects/z80-computer-project-part-1-the-cpu

Either Z80 or 6502 can conceivably be built using a breadboard with point to point soldering or wirewrap, since the clock speeds are low enough that you can get away with that. A PCB is obviously the next step, but requires apps for the schematic capture and PCB layout software.

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I can do absolutely anything. I'm an expert!

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[ElMicha]

Okay cool, I'll do the Z80 and 6502 on PCB and slowly move up from there.