The calling cards contain eight 4PST reed
relays mounted on a plug-in card with 16 cards to
a bin and eight bins arranged in pairs. Normally,
two calling cards are connected one to each
16 line bus; thus two devices up to 7,999 plus
polarity or one device up to 799,999 plus polarity
can be controlled at one time. The calling
card is constructed with a plug at both ends; 22
contacts plug into the bin which contains the 16
line bus and the relay control lines. The other
(outside) end has a 35 connector cable plug. Each
device is connected to its digiswitch by means of
an 18 conductor cable which is currently uncut.
As each device is put into computer operation, it
is necessary only to cut the cable now running
through the multiplexer cabinet and install the
plug.