you can tell how old a piece of hardware is by how many negative voltage rails its power supply outputs
@gsuberland Ah, yes. Early 70s, big 48 and 64-pin ceramic DIPs, all gold plated, PMOS. Power supply provided -28V, -14V, ground, and +12V. Hahaha.
I think there were few (if any) 48- and 64-DIP in the early 1970s. AFAIK, 64-DIP showed up around 1976 with the TMS9900 (NMOS). The earliest 48-DIP I recall seeing was the Am2903 (bipolar), a few years later.
There was less standardization of supply voltages with PMOS, but it was fairly common to see -12V and +5V, often with no 0V rail ("ground"). That was used rather than a single 17V supply because you could get TTL compatibility by just putting pulldown resistors on the PMOS outputs.
@brouhaha These were custom "LSI" (hah) chips for in-house use, not off-the-shelf products.
I remember the 9900. Used a TI minicomputer based on it to develop code for the 4-bit TMS1000. (The one where the program counter was a pseudo-random sequence generator.) Talk about minimalist design. Lol.
National Semi also made a mini. I used that to develop code for the COPS400 which was a pretty cool microcontroller for the time.
The fun old days.
The generic chipset was originally known as GPC/P (General Purpose Controller/Processor), and the RALU and CROM were the MM5760 and MM5751, respectively. As part of the IMP family, they had more specific part numbers, IMP00A-520 for the RALU and IMP16A-521 for the IMP-16 base instruction set CROM.
I have a semi-homebrew system build with the National Semiconductor "mini", the IMP-16. It has a CPU board made by National, and custom memory and peripheral boards.
The IMP-16 used one or two PMOS "CROM" (control and ROM) chips and four 28-pin PMOS "RALU" (Register and ALU) four-bit slices.