Posted By
gpz
on 2024-07-13
16:14:21
|  Re: 1541 modded with parallel cable on Plus/4?
"If I could have just one thing fixed, it would be the sound emulation. On a stock Plus/4 setting the sound frequency registers to the highest value ($03FE) should produce no sound. Several music players use this to turn channels off. In VICE however, this produces an audible, very high pitch tone, which is frankly painful to listen to. But I digress - I'm sure the audio emulation part is very far from anything to do with floppy stuff."
You might want to start with reporting a bug then, ideally with a test program -> https://sourceforge.net/p/vice-emu/bugs/
Please understand that right now we do not have an active Plus4 maintainer, and all i am doing here is cleaning up the userport system. Others may randomly pick up Plus4 bugs - but for that to happen a bug report must exist, without one chances are close to zero 
"The 6529 is mapped at $fd10-$fd1f, the 8 data bit is available on the userport as BK4567JF. D0 is B, D1 is K etc...
It is directly connected to the VIA #1 in the 1541.
It doesn't have /Flag2 and /PC2, so CA2 and CB1 in the VIA is not connected, and is not used. Is is not a speedos parallel cable, it is a plus4 specific parallel cable, which works with custom plus4 software, which does not rely on having a speedos ROM installed in the 1541."
OK, thats the info i was looking for - thanks. What would be an easy way to test if this works then? Currently the implementation is a bit weird, i want to change some details there, which is a bit of a risky thing to do without being able to verify that i didn't screw it up
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