Digital Equipment Corporation PDP-7A - S# 103 ?
Massachusetts General Hospital

S# 103? in storage Image ©2009 Computer History Museum

Emails from the Computer History Museum have confirmed they have a PDP-7 in storage, having originally been at The Massachusetts General Hospital, it is one of two delivered to the hospital in 1965-66.  The machine in photo (right), we think is probably S# 33, CHM have checked their machine in storage but a matching serial number has not been found, so it is now unlikely that we will find out which of S# 33 or S# 103 the photo actually is.  Either way the machine in the picture does not appear to be complete as it is missing it's tape drives.

December 2009 - Len Shustek at CHM has forwarded a few more photos of their PDP-7 in storage, unfortunately they don't go any further in ascertaining the identity of The Massachusetts General Hospital other than to confirm it came from their Psych. Res. Laboratory.  Serial numbers still need to be found, the only evident serial number on the core memory stack photo does not match the service list for either of the two machines.  The physical condition of the machine is very good if not somewhat dusty, with the front panel operator controls having suffered from the usual storage damage that PDP-7's seem to get - broken and bent switch levers.

S# 103 was a PDP-7A, and had options - 138E, 139E, 149B, 177B, 550A, KA71A, KA77A, 2x TU55.
S# 33 a PDP-7 had options - 7, 30D, 75D, 138E, 139D, 149D, 177, 444B, 555A, 649, PDP7.

The PDP-7 Service list (1972) shows that machine #103 was shipped to the Massachusetts General Hospital in January 1966 and consisted of the following options -

For descriptions of the above options see the full PDP-7 options list here.

120 PDP-7 and PDP-7A systems were forecast to be built in total, but at this time we do not have any information about the possible remaining 21 systems or who they were delivered to.  The 1972 18-bit service list, available here (6.5Mb pdf), details the 99 known PDP-7 and PDP-7A systems in the list at that time.  The PDP-7 appeared to have sold well into Government research and University sectors with 11 systems shipped to the UK alone, almost 10% of the forecast production run !.  Serial numbers are concurrent for both the PDP-7 and PDP-7A so the missing 21 could be of either type, however we are reasonably confident that the 99 systems shipped were the only ones ever built.

If you know of any information about any of the PDP-7 systems worldwide, options, location of existing systems, spare parts, ancillary bits, software, tapes or manuals, then please let us know here.

Documents associated with PDP-7 S# 33 - None at this time