One of the problems with PET expansion is the IO chips are not decoded properly. Each chips uses one unique address line to enable the chip... all to save one measly '138 decoder. $E81x - PIA 1$E82x - PIA 2$E84x - VIA$E88x - CRTC If those lines were decoded properly there would be all kinds of free space: $E83x, $E85x, $E86x, $E87x, $E890-E8FF.Instead, selecting an address with 2 or more of those lines will enable 2 or more chips at the same time.Example: $E83x would select both PIA's at the same time... not good. In any case, AFAIK, the $E80x space is free on all pets. BTW, I have done a little work on the VYMS-20 cart - replacing the RCA video/audio jacks with a 1/8" TRRS jack and also adding a reset button.I'm hoping to get more done this summer. Steve From: Mia Magnusson <mia@plea.se> To: cbm-hackers@musoftware.de Sent: Saturday, July 14, 2018 2:54 PM Subject: Re: F18A MK2 Den Sat, 14 Jul 2018 00:26:54 -0400 (EDT) skrev ernie chorny <chorny@bell.net>: > Ooh! Possible sprites on the VIC -20! > > What's next? Sprites on the PET? The "problem" with PET is that it's not obvious where in memory to map hardware expansions, as different models have free memory at different places. -- (\_/) Copy the bunny to your mails to help (O.o) him achieve world domination. (> <) Come join the dark side. /_|_\ We have cookies.Received on 2018-07-14 22:00:04
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