behaviour of classic PDP-8 frontpanel

Josh Dersch derschjo at gmail.com
Tue Oct 30 13:08:26 CDT 2018


On Tue, Oct 30, 2018 at 8:07 AM Klemens Krause via cctalk <
cctalk at classiccmp.org> wrote:

> Is there anybody out with a working classic PDP-8?
>
>
> Now my question to other classic-8 users: What does your machine do, if a
> program is running and you press one of the front keys, which shouldn't be
> pressed while a program is runnig: <START>, <DEP>, <EXAM>?
> Logically it makes no sense to press these switches if the machine is
> running.
>

On our Straight-8 at the museum, hitting START appears to cause the running
program to hiccup (I assume it's re-STARTing but who knows from where).  I
was unable to investigate whether memory occasionally gets stomped on
during this process (no time at the moment).  DEP, EXAM or LOAD ADDRESS
causes program execution to stop and the specified action is (apparently)
taken, though who knows what it's depositing to or examining from :).

- Josh


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