8-bit computer from scratch

https://ciernioo.wordpress.com/

by danielam • 10 years ago

94 19 10 years ago

ciernioo.wordpress.com

Retr0spectrum• 10 years ago

From the title, I assumed "from scratch" meant logic gate, or even transistor level. It's still very cool though.

honua• 10 years ago

Yeah this is what I was expecting too

bottled_poe• 10 years ago

Why stop there? From scratch should involve extracting the materials from the Earth.

ss248• 10 years ago

I wouldn't mind actually. That toaster thing was interesting.

13of40• 10 years ago

You can make a razor blade diode or a pyrite diode, so I wonder if there's some way to make a make a transistor out of household junk...

Dylan168072• 10 years ago

Because that's the point where you take things that don't compute, and make something that computes.

delinka• 10 years ago

"If you want to make an apple pie from scratch..."

colejohnson66• 10 years ago

Check out the Megaprocessor[0]. A guy made his own "processor" out of roughly a hundred thousand transistors, resistors, etc. Really interesting project.

[0] http://www.megaprocessor.com/

userbinator• 10 years ago

Relatedly, a discrete 6502 built with a little over 3K transistors:

http://monster6502.com/ as seen on HN https://news.ycombinator.com/item?id=11703596

beachy• 10 years ago

So impressive, but I am so happy to never have any reason to need to do anything like this myself. I used to fix IBM mainframes like 3033s back in the day, and debugging computers made up of gajillions of interconnected frames, boards and cards, under immense pressure, was truly the stuff of nightmares. After hours or even days, victory was finding a ringing signal with your scope, caused by a loose trilead. Then you went home and slept for a day.

Animats• 10 years ago

Hint: when posting images of schematics, make them big enough that readers can zoom in and read the numbers.

It's interesting to see this done with so few ICs. Early Z80 machines had a much higher part count, because a lot of external support was needed to talk to anything. Today we have the "system on a chip", with lots of onboard peripherals, but a Z80 is just a CPU.

The predecessor to the "system on a chip" was the semi-custom "junk chip", which contained unrelated stuff the standard chips didn't have. He may be using some of those to get the parts count down. Can't tell; schematic too small.

DanBC• 10 years ago

Did you check the downloads? I think the schematics there are going to be more readable.

TheOtherHobbes• 10 years ago

One of the features of the Z80 was built-in memory refresh, so it needed a lot less glue logic than most processors, which had to have external registers and latches to handle the refresh cycles.

Way back I used to hand solder Z80 embedded controller board prototypes, and they never needed much in the way of chippery.

In an S100 system the biggest extras were the video (formerly VDU) cards, and the memory cards.

Both were limited by the RAM of the day, because RAM came in tiny sizes like 1 bit x 16k dynamic or 2k x 8 static. So you needed a lot of chips on a separate board for what was really not much RAM at all.

Also, money. 64k boards cost over $1000, which is > $3k in modern money.

Now you can get 8 bit x 256k static RAM on a single chip, so you can park that next to the processor without a separate card. With a bit of glue you can even share it with the graphics hardware, eliminating any need for separate graphics RAM.

asimuvPR• 10 years ago

Specially like the wooden case and keyboard. Wish the schematics were a bit easier to read, though. :)

rietta• 10 years ago

Don't know why, but the CatChurn game jumped out at me as being written by Yahoo Software in 1982 (the year I was born). There does not seem to be a Wikipedia entry for this company, but the address appears to be a residential condo as per Google Maps - https://www.google.com/maps/place/10970+Ashton+Ave,+Los+Ange....

Interesting to see a little bit of history and how game writers really were working from home on an idea even in the early days.

awt• 10 years ago

I am currently building my own Z80 based computer. It's been a great experience building up my electronics lab and I wish I had done it years ago. I recently received a Russian made Z80 that I ordered off ebay. Probably the only product of Russia I've ever owned.

8-bit computer from scratch

Related Stories