80-Bus News

S1:–	Is the main timing contact and is found on the left hand side of the unit. There are two set’s by the timing wheel and it’s the inner set.
S2:–	Is the space and back-space contact,it’s situated at the rear of the unit, second set from the right.
S3:–	Carriage return and line feed contact, rear of the unit, extreme right.
S4:–	CR interlock, right hand side toward’s the rear. If CR is operated, S4 can be seen to move.
S5:–	TAB interlock, rear of unit extreme left.
S6:–	Right hand side, closes when in upper case.
S7:–	Near S6, closes when in lower case.

Note that all magnet’s must have a diode across them for two reason’s.

1/. To protect the driver transistor’s.
2/. To make the magnet’s release as quickly as possible.

The 5 volt supply for the 74LS00 was provided by the PIO socket on the Nascom, so that if a 12 core screened cable is used (i.e. screen = Ov), there will be ONE spare way.

The print magnet’s, R1 through CK, are underneath on the left, and from left to right are:–

T2 CK T1 R2A R1 R2 R5

As for the control magnet’s, it’s simply a matter of applying power to each one in turn and noting the effect. They are situated on the right hand side, underneath.

March–April 1983 · Volume 2 · Issue 2