Via Via

From: Bo Zimmerman <*bo_at_zimmers.net*> Date: Wed, 3 May 2023 15:22:31 -0700 Message-ID: <7ab81d77-0b6a-a96a-699e-d840442eb394_at_zimmers.net> · bo_at_zimmers.net

I'm trying to trigger a CA1 nmi interrupt on an 8032 via the user port, 
and for some reason, all my reading isn't helping me with reality.

The following BASIC program illustrates what I've been trying:

10 for i=1to4:read a:poke4096+i,a:next
20 poke 148,0:poke149,16:rem set nmi-handler to 4096
30 poke 59469,0:poke 59468,130: activate CA1 irq
40 end
99 data 238,0,128,64: REM inc 32768:rti

I then pull the CA1 pin on the PET user port (bottom row, second from 
the left) from HIGH->LOW, and expect the screen character to change, but 
nothing happens.

I have read at least 6 different documents/book sections talking about 
VIA programming on the PET, and have no idea what I did wrong.

Please help me CBM-Hackers!