So... having found some time to have a look at these beasties, I find that overall I'm still as puzzled as before. And one of these cases where documentation can be TOO old... My one vintage HP catalog predates these CPUs by a couple of years. The catalog only lists the HP2116. I wandered through the card cages in both machines (fairly diverse configurations) and the designations look like this: Machine 1 Front card cage Rear card cage DCPC 13037 Intf Memory Protect Grd True In/Out M.E.M. Grd True In/Out 64k HSM 12747H Microcircuit 64k HSM 12747H BACI 12966A 64k HSM 12747H 7970 Mag Tape 2 64k HSM 12747H 7970 Mag Tape 1 64k HSM 12747H Line Printer 64k HSM 12747H Time Base Gen Mem Contr 2102E F.E.M. Main Logic? (under chassis) Machine 2 Front card cage Rear card cage DCPC Jumper Memory Protect I/O Buffer M.E.M. 8 Chan Mux Standard Memories Bus I/O (256k memory) 1 Standard Memories 2 (256k memory) Disc Intf 2 256kw 12749H Disc Intf 1 256kw 12749H 3 Mem Contr 2102E 4 BACI 12966H 12821A Disc Intf Time Base Gen F.E.M. Main Logic? (under chassis) (pictures are on the MiniComputers page at The Computer Garage) Some of the cards are fairly obvious as to function, (memory, time base gen, etc...) but some of the designations are a bit vague, and in any case I still need to find docs on this critter and the cards. The cards designated as 1,2,3, & 4 are all identical, and look like multi-channel serial I/O cards. The only obvious designation are etched on the card and read 5180-1953 and 668298. They are HP cards... Any information on these critters would be greatly appreciated! After the usual pre-launch checks, all of the (apparently) optional cards were removed from the card cages and the units were powered up. Curiously, they both act identically in that they seem to have some front panel function, but the CPUs seem to be hung pretty hard. No odd sounds or loss of magic smoke, so an initial suspicion is a configuration error common to both units. The card cages only have specific card notations on a couple of slots, so there is the obvious question of proper card positioning. (no idea if the cages are a parallel bus or not) Help??? Thanks; -jim --- jimw(a)computergarage.org The Computer Garage - http://www.computergarage.org Computer Garage Fax - (503) 646-0174