BID 770 (Topic/Tenec)

The complete BID 770 system.  (Photo via the COMWEB Museum)

BID 770 is on the right with a Model 40 (center) for off-line encryption/decryption. It  was a British built crypto machine and was used by Canada's foreign service communicators at smaller diplomatic missions to communicate with various government departments.

TENEC was the unclassified code name used by External Affairs Canada for the following  hardware configuration: BID-770/TTB-77/Teletype Model 40 /Model 28 tape reader.

TOPIC was the British classified code word for the BID770.  TOPIC in its UK usage was intended to be used on-line. In External Affairs Canada, it was used off-line.

Bruce MacMillan adds to this. "When I was posted to Hanslope Park in England (1972-77)  I had the opportunity to train and be part of the three person acceptance crew for the new BID 770 'Topic'.  The British Foreign Office  had just accepted 10 units
(1975) from Plessey to test before placing them  into the British System.  Canada had opted to purchase about 100 units initially,  but they had to pass acceptance testing.
Acceptance testing was quite thorough.  We went through each circuit board to prove they were safe and secure.  If a node went open, grounded or shorted, could or would plain language be transmitted?  Also how did they respond to over voltage or under voltage mains  power ?  In those days it was nothing to have heavy voltage spikes or drops in many countries.  I specifically remember the Canadian Embassy in Bogota, Columbia. Every time the elevator went up or down and passed the 3rd floor where our Embassy was,  the mains voltage would drop about 25 volts.  That played havoc with everything electronic!

It took three of us almost a year of steady work to verify and prove the BID 770 was good to go."

TheTeletype Model 40 component of the BID770. (Photo by Jerry Proc)
The Model 40 was a simple word processor with data stored on magnetic tape. It provided input/output  for a secure store and forward messaging system. The two tape drives on the right used cassettes to store data being transmitted and received. A printer provided page copy that was distributed to the message addressee.
This BID 770 crypto unit is displayed at the Bletchly Park Museum. (Courtesy Old Foreign Affairs Retired Technicians web page) 

Contributors and Credits:

1) David Smith <drdee(at)>
2) Old Foreign Affairs Retired Technicians web page  <>
3) Bruce MacMillan <[bruce-macmillan3(at)>]

Back To Menu Page
May 21/12