A few years ago I bought one of these on ebay:
It worked when I got it, but since then I think damp storage conditions = got=20 to it and now it powers up with just a single digit lit and the keypad = only=20 toggled the internal/external mode. I don't have the manual for it = (although=20 a scanned PDF copy is available for $20), and when I removed the lids I = saw=20 that there was a huge PCB with perhaps a hundred ICs, in sockets, with = the=20 most recent date code 1980. There is a plug-in computer card with = several=20 Intel 4004 processors and various other ICs in the chipset.
A Wiki search showed that these are the first single chip CPUs, = introduced=20 by Intel in 1971, and apparently they are highly prized as collectibles = and=20 some are worth several hundred dollars.=20
A search on eBay showed some at high asking prices but no active = bidding.
Actually I dug out this piece of equipment with the intention of=20 cannibalizing a BNC connector for a little prescaler I built so I could = use=20 my Fluke 45 to read clock frequencies for some PIC boards. I used a =
74HC390=20 as a divide by 100 so now I can read my 14.7456 MHZ clock as 147.45 KHz, =which is precise enough for my needs, and I really don't have room on my =
bench for a rack mounted instrument. So now my question is whether to=20 continue cannibalizing the unit, which has some nice components like a =
10=20 MHz crystal oven oscillator, and possible sale of the INS400x chips, or = get=20 the manual and try to get it working. It has nine digits and some nice=20 features such as programmable gate level and arithmetic functions, with = 100=20 MHz on A&B and 512 MHz with the prescaler on channel C, so it's a pretty =good instrument and supposedly meets MIL standards. It is = well-constructed.
If anyone is interested, please let me know. I only paid about $40 for = it=20 (plus $35 shipping), and I hate to destroy something that could be = useful or=20 a valuable addition to an electronics museum. Please let me know what = you=20 think.
Paul=20