- on Miscellaneous
- Published in issue 7/1989 on page 22
22 032 COMPUTERS When during a computer print-out something goes wrong with the printer, such as the paper getting snarled up, the only way to stop the operation is normally to switch the machine off. That may be a useful, but certainly not an elegant, method: a reset knob, on the other hand, is. Nearly all printers with a Centronics interface have a reset input at pin 31 of the Centronics connector (consult the hand- book). That input is used in many MS-DOS systems to set the print- er to a defined starting state and at the same time to empty the buffer. The input may, of course, also be used to connect a reset switch to. The diagram in Fig. la shows how such a switch may be made quite easily. The 1 k12 resistor prevents the computer output being short-circuited when the printer is being reset. Users of the recently published printer buffer (Ref. 1) can fit the switch in the buffer or expand the existing switch so that the printer is reset at the same time as the printer buffer. ...