Continuation of my 4004 project abandonded couple years ago. I have secured enough basic chips for both 4004 and 4040 systems, consisting of the CPU, clock generator, couple 4001 RAM chips, 4289 standard memory interface for the program memory and 4265 general I/O. So far there is basic HD44780 driver printing couple text lines hardcoded in the program memory.
I got back to this project which was shelved multiple times and it's likely to be shelved again but hopefully some serious work will get done before that :)
With reviving efforts I found couple problems: original LCD appeared to be shorted, it didn't survive -10 volts on the Vee line controlling contrast. Luckily I got another from Mostek MK38P70 piggyback demo. The other problem is with my serially programmable parallel memory which I made for easy prototyping. I found out it reads out rubbish at regular 5 V but at one diode lower drop it works reliably enough. I haven't found the reason why that is yet, will have to measure around the board when I have time. Meanwhile you can look at the board there: https://easyeda.com/jan.tichavsky/ISP_FLASH_ROM-f34bf22249cc4cecb7377b1c78951f8e I believe the Gerbers aren't exactly up to date and I fixed couple close traces that did or could pose a problem. Schematics and BOM are unchanged and current though.
I want to move on from the breadboard to PCB, some initial work was done here https://easyeda.com/jan.tichavsky/Intel_4004-26742a05de344889a50cfec7e2f6f927 The plan is to have simple but somewhat complete MCS-4/MCS-40 chipset: 4004 or 4040 CPU, 4201 clock generator, plenty of 4002 RAM, 4289 standard memory interface, 4265 I/O chip, and place for 2732/2764 program memory. I will need to sort out power supply, I'm partial to vintage 723 regulator, some interface connector, and LED indicators which should be ideally through hole but those take a lot of space.