largest possible/workable floppy format via disc image or gotec type emulation

[zhulien]

Hi


What would be the largest possible/workable floppy format via disc image or gotec type emulation?  I am guessing we could have 255 sectors, 255 tracks... 255 sides or are side controlled via bit?

[freemac]

Hi

What would be the largest possible/workable floppy format via disc image or gotec type emulation?  I am guessing we could have 255 sectors, 255 tracks... 255 sides or are side controlled via bit?

You have double-sided disc  DS80 (~720Ko) like Batman demo using one disc, no special ROM needed here to use them (but cat does show just files on 128Ko area), does run simply if you plug a 3.5 player to an original CPC in fact.

And ParaDOS DOSD2 (~720Ko) using ParaDOS 2015 ROM, where cat does show everything and is them cool for working with data purpose (music, picture, text ...) and is retro compatible with softwares (sound tracker, painter, protext...), ParaDOS ROM does replace AMSDOS ROM, so no problem with DEMO detecting added ROMs.

Both usable as disc image.

[arnoldemu]

Hi


What would be the largest possible/workable floppy format via disc image or gotec type emulation?  I am guessing we could have 255 sectors, 255 tracks... 255 sides or are side controlled via bit?

The 765 disc controller supports 4 drives (hardwired to 2 on CPC), 2 sides, up to 256 tracks and up to 256 sectors per track.


In reality, 84 tracks is max on a 3.5" drive and 42 on a 3" drive, and the track size is around 6KB for MFM so if you want to maximize your track usage you need to use "8K" sectors, with ~&1800 bytes useable (more data will fit if the data and clock windows are shrunk by using a custom track writing hardware - the PLLs can handle a slightly higher bit density than normal).


More sectors doesn't equal more data because of the gaps between the id and data fields.


Use less but larger sectors.


The software on a Gotek will take a dsk file and convert it to a raw MFM track, so it needs to fit inside 6KB.


Are we talking fake images that can't be used on CPC or images that can be used on CPC? In that case just use IDE. Plenty of interfaces exist and writing software to read/write them is not that hard and there are plenty of existing OS for CPC.

[Bryce]

Hi


What would be the largest possible/workable floppy format via disc image or gotec type emulation?  I am guessing we could have 255 sectors, 255 tracks... 255 sides or are side controlled via bit?

I'm not sure if the µPD765 allows up to 255 sectors/tracks, never tried. As far as sides are concerned, the 765 can handle 4 2-sided drives, so with a little hardware trickery, you could make it think it has an 8-sided disk.

Bryce.

[zhulien]

i mean purely images for use with a gotek for instance.

[GUNHED]

You forgot the sector size, use 4 KB instead of 512 bytes.