This was the first of the 360 range of systems to be delivered to a customer. Developed at IBM Hursley laboratories in the U.K. the machine had a two byte wide access to memory with an access time of 2.5 micro seconds and a maximum central core storage of 356 K bytes. The operator consul was an IBM 1052 (a version of the IBM Golf Ball typewriter).

Transformer Read Only Storage (TROS) controlled both the CPU and internal I/O byte and selector channels. These two types of channels, selector and Byte Multiplexer were used to access the various I/0 devices using IBM's Standard Interface. The selector for what was termed high speed peripherals such as Disk or Tape, and the Byte Multiplexer for the slower Printers, Card and Paper Tape devices. A detailed description of the Standard Interface can be found elsewhere in the Museum. 

Data flow diagrams for the Mod 40 taken from CE handbook. The left hand picture shows the selector channel and the right hand the CPU. The two drawings match up to give the complete data flow picture.

This page was last edited on 08/02/00