Posted By
IstvanV
on 2007-06-05
11:32:27
|  Re: plus4emu 1.1.0
Actually, the problem with "Exacting demo" was caused by not emulating correctly the CPU I/O port data direction register ($0000). While there is normally not much use setting it to anything other than the default of $0F, this demo has a protection that temporarily overwrites the I/O port registers with garbage, and with the original code, this caused the 1541 ROM to lock up because of a bogus ATN signal. It was only a coincidence that with some older DOS revisions the problem did not seem to occur. Anyway, I have fixed the $0000 register to work correctly, and now the demo loads without problems; I did not test it with the 1541-II yet, but now that I found the real problem, I would expect it to work as well. However, the ROM version I mentioned earlier (1540-c000.325302-01.bin and 1541-e000.901229-05.bin) is apparently also used by YAPE, and it is probably a safe default. I still include the 1541-II DOS with the ROM package as 'dos15412.rom', and you can easily load it in the machine configuration.
What still needs some testing is the new alternate 1541 timing code that fixes several loaders that previously failed; so far, it seems to work quite well, even if I used a hack to work around the loader used in e.g. Crackers' Demo 3.
|
