Recently, I found the YouTube playlist by Ben Eater about 8 bit computers. I always been fascinated by electronics and computers. After watching the complete series, a huge mystery dissipated and I finally understood how the first computers works.
An 8-bit computer is a piece of art and I want one on my office wall. So I decided to make my own version of a SAP-1 (Simple as Possible).
Breadboards are very useful but for a permanent design are not that great and also… are ugly as fuck and I don’t want more than 10 breadboards hanging on the wall. Another problem, if someone hit it accidentally it will probably unplug something, and troubleshooting it’s not one of my favorite hobbies.
So what I decided is to use PCBs. I used some of those chinese pcb manufacturers in the past and it’s really cheap to produce a good looking pcb.
What I’m planning on making is to have multiple PCB each one with a specific function an all of them connected by 2 buses, an 8bit bus for data transfer and the other one for signals.
The main purpose is to be able to display each step of the computer. To achieve that, all components will have its content displayed with LEDs and all the active parts will have some kind of flag.
I’m currently reading the book that Ben uses for reference, Digital Computer Electronics by Malvino. The problem is that a lot of the components used are really dificult to find or they’re really expensive. Paying 25€ due to shipping costs for an IC that cost .2€ it’s not an option.
I’m looking for components at Futurlec and LCSC, most logic gates are available in LS or HCT form.
I made some changes in the design. I decided to use the 28C64 insteed the 28C16 EEPROM, this last one is unavailable and the ’64 it’s easier to write (doesn’t require a pulse).
Another change it’s the RAM. I’m going to use a LY6264 8K x 8, I could not find the one that Ben uses.
I’m currently working on the schematics of each module, trying to use easilly available parts with a similar function. Once I finish al the schematics I’ll posts them.
oFurafollas 