Support for P64 disk format?

[robertjmcintyre]

There are a handful of titles that can't be successfully represented in the .g64 format, primarily due to multi-density tracks. There's several discussions on lemon64, etc. on the topic.

We are able, however, to create working .p64 images of those titles, so would like to ask for you to consider adding support for that format in the 1541 Ultimate II (and Ultimate 64).

You can find a description of the file format here:

https://vice-emu.sourceforge.io/vice_17.html#SEC404

and VICE has full support for it. If you decide to take this on, various images for testing can be provided.

[mrdudz]

IIRC the drive emulation is GCR based, not flux based, so P64 can not work

[GideonZ]

@mrdudz This is only partly true. The GCR bytes are serialized at the rotation rate and then again parallelized at the sampling rate of the drive clock. This allows images to have bytes that are not aligned to still work. True, the DMA unit in the drive emulation cannot read flux distances directly, but technically this is not a big change. Firmware wise this might be a bit more complicated; it also takes a lot more RAM.

[mrdudz]

Yeah by "GCR" i meant "decoded bits" (vs raw flux pulses). ie the equivalent of what VICE does for G64