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EMIDEC hardware

These were the days of room-sized computers, running on transistors - strings of grey metal cabinets full of circuit cards and other gubbins. Main storage (actually known then as "core store") was a matrix of laced ferrite cores - quite visible in one of the cabinets. Main storage capacity was a monstrous 1,024 words, each of 36 bits - just over 4k in modern byte terms. Backing storage (equivalent of hard disk) was provided by magnetic drums rather than disks - to the extent of 4,096 registers - say 20k!! Anything else had to be stored on magnetic tape... that's one-inch wide magnetic tape in huge reels... as seen in contemporary films, whizzing backwards and forwards (though these really only went one way at a time unless they came across an "NCT error"), as the only moving objects worth filming.



(manufactured by Elliott Automation)
This was the prime form of input for both data and programs.

Paper tape reader
- a temperamental beast - only used for EMI Records sales order details

Anelex line printer
There was also a Samastronic printer, but it was older, bigger and slower, and rarely used.


Tape drives (Ampex)
Huge reels of one-inch magnetic tape mounted in the vertical drive, with its glass door. Loading the tapes was an art-form. One had to pull out just enough tape to allow for a loose loop at either side of the read/write head, and enough to wind round the receiving (bottom) reel to hold with friction. The drives were vacuum-sealed when the door was closed, and the vacuum was used to buffer the stop-start of the drive. If the size of the loops was wrong, the tape would snag; if insufficient tape was wound on to the receiving reel, the vaccuum would whip it off and flail it around inside the drive!

Tapes were stored in a bunker near the computer room - supposedly fireproof, it had a thick, heavy self-closing door.


Electronic gubbins
Circuit cards were about 8" square. There were racks of them in the cupboards which comprised the Emidec.

Circuit card - click to enlarge    Circuit card - click to enlarge    

See also Peter Wooledge's ICL website at

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