Nuclear Data ND-812 info...

I stumbled across this thread from a year ago. I owned a BR2412 and designed and built a serial interface for it around 1981 or so. There were plans for this machine, but grad school interfered and when my home was flooded the computer hit the garbage. The BR2412 used a gel-cel battery to back up DRAM in the event a power failure occurs. Simply turning the computer off didn't drop power to the memory. You are correct this was a Bunker-Ramo version of the ND812; the BR2412 was used for factory automation. The ND812's design was highly motivated by the PDP-8 family - 133 ohms unidirectional busses, memory banks, no stack (used a "jump and save" instruction with some additional hardware to determine whether an indirect jump referenced a subroutine return address or something like that). The clock was 2 MHz 8-phase derived wire-wrapped; although the motherboard looked kludgy, the cold-weld contacts were extremely reliable and the rat's-nest of wiring reduced electromagnetic effects. The vast majority of the circuitry was based on Fairchild's 9000 and 9300 family of TTL SSI and MSI parts. Nuclear Data tried to compete with NCR with this machine and failed miserably. Although ND could build excellent hardware, they apparently never got the software side up to par. Thanks for the memories! Cordially, Bo Bohdan Bodnar, PhD Lemko Corporation 1700 East Golf Road, 7th Floor Schaumburg, IL 60173 +1 847-240-1990 x238 www.lemko.com