HP 2112A

All the HP 21MX posts got me interested in finding out what I have with the HP 2112A I recently got and what I'm missing. The back end (where all the I/O cards go) is empty. In the front there is the DCPC, Memory Protection, M.E.M. (Memory Extension Module), 3 memory cards and Memory Controller. I believe I can see 3 loader ROM chips installed on the CPU board (assuming I'm looking in the right place - front right side of the board as I'm facing it). Of the 3 optional Control Store modules in the back, the middle one is mounted under the CPU, but the other two are not there. The back label says "2112A" and lists the following options: 12978A (Writeable Control Store Diagnostic) 12992B (Disk boot ROM) 12992C (Terminal boot ROM) I figured out from the bitsavers document and another online document that these are the 3 ROM options I saw. The paper tape loader ROM is soldered in with the M-series machines, according to the online documents I read. 12897A (DCPC) 12892A (Mem Protect) 13187Ax2 (16k Mem) So it looks to me like I need some I/O boards (13175 disk drive interface, 12966 or 12968 terminal interface, 12597 paper tape interface), and probably the other Control Store modules to flesh this thing out (not to mention the cables to connect to peripherals). Does all that sound right? Richard Lynch