HP-2108A w/64k
Images: http://rikers.org/gallery/hardware-hp2108a
Boot ROMS
- 00 (U36) - 1816-0420 soldered - paper tape loader
- 01 (U16) - 1816-0639 socketed - early 7900/7905 disc boot ROM
Original memory slot contents
- 110 - D.C.P.C (Dual Channel Port Controller)
- 111 - MEM. PROT.
- 112 - empty
- 113 - MEM CONTROLER - 2102A
- 114 - 8K MOD - 2102A
- 115 - 8K MOD - 2102A
- 116 - 8K MOD - 2102A
- 117 - 8K MOD - 2102A
- 118 - empty
Original IO slot contents
- 18 - TERM
- 17 - empty
- 16 - empty
- 15 - empty
- 14 - TAPE PUNCH
- 13 - +8 BIT DUP REG
- 12 - empty
- 11 - empty
- 10 - HS TERMINAL
Broken IBL
Machine seems functional, but IBL will not load any data. It does set the overflow bit and set P to 177700 so something runs.
I tried moving the RAM around, and it seems to make no difference. After a bit of testing, I determined that the card edge connector on the ribbon cable from the front panel is bad. It's a 3M 3415-0001 50 pin .1" gold plated IDC card edge connector. If anyone wants to send me one, that'd be great. 
I swapped panels with the 2112, and now the 2108 IBL works, and the 2112 does not.
Replaced the cable on the front panel, and both are now operational.
Serial
http://www.cs.ubc.ca/~hilpert/e/HP21xx/io12531BCD.html
HP-IB
Picked up a 59310-60101 "BUS INPUT/OUTPUT INTERFACE" to try interfacing with HP-IB / GP-IB / IEEE-488 systems. I don't yet have a cable, but I hope to pickup an HP-9122D to interface with soon.