The Fairchild FST-2 computer was used to control a family of Semiconductor ( chip ) testers I guess from sometime in the mid 1970s to around the mid 1980s. The family of testers were branded as "Sentry", "Sentinel" and "Series10" ( maybe some others ). The FST-2 was a 24-bit machine with its memory interleaved between odd and even addreses. When the CPU was reading/writing to an odd address, a peripheral could address an even address and vice-versa using DMA. Early machines were booted from tape, but newer machines had a PROM boot board which allowed booting from 8" floppy, hard-disk, tape ( and possibly a network. ) Early machines had 25 bit wide memory with a parity bit, while the later machines had 30 bit wide memory which provided error detection and correction. Control of the tester was via two busses known as the long-register bus and the short-register bus. If you come across an FST-2 which can be powered up, set the console switches ( piano keys ) to 06760000 in octal and press STOP, RESET, LDP, LDC and START. The machine should waken up. There are a few stand-alone FST-2s kicking around without any tester hardware. These were used as a FACTOR compiler co-processor for a development system which was based on the HP1000. Most FST-2s will be part of a chip tester. If the chip tester is still working, the whole system is still quite valuable. Even as a source of spares. Although the tester has a lot of different power supplies the FST-2 probably ony needs 5.0V and the RS-232 voltages to get running. The FST-2 ran an OS named M3 ( "M Cubed" ) and was programmed using a FORTRAN-like language named FACTOR, ( Fairchild Algorithmic Compiler Tester ORiented. ) Most Sentry testers could test digital chips with 60 pins up to 10 MHz. Some later Sentrys could test up to 120 pins at 20 MHz. I remember FST-2s being very slow to compile FACTOR programs. Most users ended up compiling their program and test patterns ( Vectors/Truth-Tables ) on a VAX. Fairchild ( and later Schlumberger ) provided really good in-depth training and documentation for the CPU and the testers for hardware maintenance and programming. The manuals which were up for grabs were either manuals/schematics which were shipped with a tester, or training manuals which some engineer picked up in San Jose or Munich.