[comp.sys.cbm] C64 user port reset

fred@cbmvax.UUCP (Fred Bowen) (04/28/89)

In article <6957@bsu-cs.bsu.edu> wendi@bsu-cs.bsu.edu (Walter H. Dick) writes:
>Can anyone tell me how I can ground pin 3 (User Port), so the computer
>will do a reset?  Thanks in advance!

Ideally you would want something which would debounce the reset switch,
similar to the circuit on the C128.  At the least, you can afford the system
some protection any number of ways, such as:

                  momentary   1N914     110 ohm
        ground-----switch-----diode-----pullup------intres
           |                   |<         |            |
         pin 1                          pin 2        pin 3      (user port)

This is for a C64, of course.  Use at your own risk.  This will not work on
a C128, in which the *EXTRES (external reset- user, serial port) and the
*INTRES lines are separated (besides, the C128 has a perfectly repectable
reset switch of its own).
--
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