NCR 725 / 605

This machine is a “barn find”, discovered while following up a lead for a glass TTY terminal.

Its previous owner obtained it at auction in the early 1980s, as cheap computer power for a personal project. The project did not proceed and the 725 was put into a barn and left for over 30 years. It appears to be complete and largely unmolested. The massive power supply appears to have been the main site of past work, the remainder appears intact. There is some external rust but the internal components show very little corrosion. The 16k core memory unit did not appear to be in bad condition.

The machine is currently in storage while its restoration prospects are considered. Reasons for optimism include:

It appears to be commplete, with no serious damage or deterioration
It is based on simple TTL technology, this is repairable with sufficient data and time
There appears to be a strong ex-NCR community that may well have kept useful data and/or software

DoPECC would like to be able to restore this machine but will require the following before being able to proceed:

any and all technical and circuit information for the 725 computer, 605 processor and peripherals
any software, on media or as listings. The entire software environment has been lost
recollections, stories or general information from past users or technicians

Update 2026

Over many years, more iformation was gathered. The main thing learned was that the NCR 725 was part of a tightly-integrated retail sales system and only ever ran software dedicated to that purpose. The software was prepared on mainframes, cross-compiled and loaded into the 725 as machine code. There was never any kind of operating system, user environment or user programming language for the 725.

With this knowledge, there is no viable path for the 725 to be restored as a usable 1970s computer. An entire operating environment would have to be developed, e.g. by porting CP/M and associated applications to NCR 725 machine code. Not a practical proposition, and even if successful the result would hardly be true to the original purpose of the 725.

The NCR 725 has therefore been documented as fully as possible and then broken up for salvage of parts that can assist other restoration projects. Tape drive, TTL ICs, core memory and power supply can all assist other restorations. The operators console has been retained as a potential blinkenlight project.