These documents describe the MCM7 variant of the Elliott (or GEC) 920M digital computer.

They were largely written during the Covid lockdown by inspection of two examples.

Wiring schedule of whole machine (34 pages): WIRING.PDF

The microprogram diagram (one A3 sheet): UPCHART.PDF

External connector interfaces (7 pages): INTERFAC.PDF

Logic Sub-Assemblies, LSAs (7 pages): LOGICSUB.PDF

Layout of LSAs on Control deck (1 page): CON-DECK.PDF

Layout of LSAs on Register deck (1 page): REG-DECK.PDF

Control circuit diagrams (14 pages): CON-CIRC.PDF

Conjectured internals of carry LSAs (3 pages): CONJECTU.PDF

A brain-dump of explanations (16 pages): EXPLANAT.PDF

There are NO Store circuit diagrams, or details about the Store LSAs or their layout.

Here is some background information about the MCM2 & MCM5 variants of the 920M.

920M marketing flyer front and rear

920M Facts Cards 1967 and 1968