4 ms·
8-bit computer from scratch
- Retr0spectrum 10y agoFrom the title, I assumed "from scratch" meant logic gate, or even transistor level. It's still very cool though.
- honua 10y agoYeah this is what I was expecting too
- bottled_poe 10y agoWhy stop there? From scratch should involve extracting the materials from the Earth.
- ss248 10y agoI wouldn't mind actually. That toaster thing was interesting.
- 13of40 10y agoYou 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...
- mrob 10y agoJeri Ellsworth has built working transistors at home. Point contact germanium BJT: https://www.youtube.com/watch?v=vmotkjMSKnI https://www.youtube.com/watch?v=vmotkjMSKnI Etched silicon FET: https://www.youtube.com/watch?v=PdcKwOo7dmM https://www.youtube.com/watch?v=PdcKwOo7dmM The rusty razorblade + pin point contact diode doesn't need anything special because it's a Schottky diode, with a metal/N-type semiconductor junction. If you probe lots of places you can find an N-type region where the dopant is random impurities. But the transistor needs both N and P-type regions, so I don't see any way to build one with common junk. Jeri's point contact example works by diffusing phosphorus from phosphor bronze into commercially produced N-type germanium using a high current to heat it. Phosphor bronze is arguably household junk but I don't think germanium diodes are.
- Dylan16807 10y agoBecause that's the point where you take things that don't compute, and make something that computes.
- tmptmp 10y ago>>Because that's the point where you take things that don't compute, and make something that computes. Good point but I didn't get it quite right. What is your definition of "things that compute"? I am curious.
- Dylan16807 10y agoA device that can use a mathematical process to figure something out. A single transistor definitely doesn't compute. A single gate? Eh, not really. A design with a couple latches and an adder that can perform SUBLEQ? Yeah that computes if you attach a ram. A non-turing-complete pipeline of math functions? Yes, that computes, though why make that when it takes more gates than a microprocessor needs.
- delinka 10y ago"If you want to make an apple pie from scratch..."
- colejohnson66 10y agoCheck 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/ http://www.megaprocessor.com/
- userbinator 10y agoRelatedly, a discrete 6502 built with a little over 3K transistors: http://monster6502.com/ http://monster6502.com/ as seen on HN https://news.ycombinator.com/item?id=11703596 https://news.ycombinator.com/item?id=11703596
- abraae 10y agoSo 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 10y agoHint: 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 10y agoDid you check the downloads? I think the schematics there are going to be more readable.
- TheOtherHobbes 10y agoOne 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.
- deleted 10y ago[deleted]
- asimuvPR 10y agoSpecially like the wooden case and keyboard. Wish the schematics were a bit easier to read, though. :)
- TelAviv_1 10y agoNo it's not. It's an Z80-based computer. Not an 8-bit CPU from scratch.
- rietta 10y agoDon'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+Angeles,+CA+90024/@34.0574147,-118.4461462,18z/data=!4m5!3m4!1s0x80c2bb7ddefe82d1:0xb69d54b9167a2522!8m2!3d34.056877!4d-118.445713 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 10y agoI 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.