Den Sat, 14 Jul 2018 19:12:12 +0000 (UTC) skrev Steve Gray
> 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.
A way to get around this would be something that sits between the CPU
and it's socket.
Are there any PET motherboards where the CPU isn't socketed?
> 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
Is it possible to get S-video from that chip? If so a C64/C128
compatible 8-pin DIN connector might be a good choice.
1/8" jacks kan be a bit of a mess. Stuff with only mono audio might
have video and audio on the pins that's used for right/left with stereo
audio. If you have stereo audio and an additional signal ground can be
either on the sleeve (older mobile phones from for example SonyEricsson)
or the ring closest to the sleeve (iPhone and more modern mobile
phones from other brands). I think the rationale for Apple to move the
ground might have been to get the microphone signal away from the
headphone output signal. Also SonyEricsson used the same pin (the ring
next to the sleeve) both for composite video output and microphone
input on the same product, Vivaz, a Symbian phone,
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