[pdp7-unix] Testing ttt, and also p

Lars Brinkhoff lars at nocrew.org
Mon Oct 28 03:40:03 AEST 2019


Phil Budne wrote:
>> I'm not sure if the push buttons should raise an interrupt, and if
>> so for what kind of events.
>
> I think they do, but I can't tell you on what conditions.
>
> at src/sys/s7.s line 259, in the PI service code:
>
> checks the push button flag with spb, then clears it (if set) with
> cpb.  For most devices "flag" means a PI request flag.

Thanks, I saw thaq and figured "clear flag" would imply restore
interrupt.

I suspect something is off though, because if I "push" a button I see
the debug log goes into a pecuilar state until I type a key.

> Seems like dttt exits (in getpb) if a certain button is pushed.

Yes, the one corresponding to 2000, same as used by the system to clear
the display.  This is F8 in the simulator.

> ANY of the display related system code might have remaining
> "misinterpretations"!

Of course.  I'm glad the programs work as well as they do.  I have seen
worse.


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