[Gotek] Slow read/write on ST and other issues.

[Jeff]

I have done format comparisons between the standard TOS and FC3 layout :

All have been done from a true floppy disk and disk drive - No emulator involved here !
(Same Disk + drive for both format)
You can get the dumps (AFI format) and the pictures there :
https://hxc2001.com/disks_analysis/ST_TOS_FC3_FORMATS

TOS Disk layout :



(High res) :
https://hxc2001.com/disks_analysis/ST_TO ... TS/TOS.png

One TOS Track layout :


FC3 Disk layout :



(High res) :
https://hxc2001.com/disks_analysis/ST_TO ... TS/FC3.png

One FC3 Track layout :


The track-to-track skew is different and there are some interesting tricks on the FC3 tracks :



The FC3 format goes quite far from the ST standard to gain some read/write seconds in the FC3 tool .
The USB HxC use the standard format with ST files and take the exact format used with HFE files.
That's why you got the ST timings with ST files and that you have the exact FC3 read speed with HFE files (if you have formatted them with FC3 of course!)
Btw i am almost sure that the FC3 format can disturb some Games/demos loaders !

Some "real-life" tests are probably more interesting : How many time to copy a bunch of small files and "big" files.
This test both random and sequential accesses and this is how these emulators are mostly used.

[tzok]

Ok, that's fine, but what about track display in my .ST image? What is so special about it, that the track count display is wrong, while current track display is correct. I don't remember FF having any problems with it. It is FC3 formatted, but as far as I know the .ST image carries only sector data, so formatting program should not be an issue here, because it doesn't carry any information about track/sector headers, skew or interleave.

[Jeff]

I have checked the 80_09.st file size : 746496 bytes : This match with a 81 tracks-image (81 * 2 * 9 * 512 = 746496 bytes.)
So in fact there is no particular issue here.

[tzok]

I've tried formatting it to 82 and 84 tracks and display always shows 81, eg. "83/81". Why Atari "knows" it is an 80 track disk, while HxC doesn't know this?

[Jeff]

I've tried formatting it to 82 and 84 tracks and display always shows 81, eg. "83/81". Why Atari "knows" it is an 80 track disk, while HxC doesn't know this?

It's definitively an 81 tracks disk image ! What is displayed on the emulator is the max number of physical tracks currently available with the selected image.

I suppose that the ST just read the boot sector to get the number of tracks/sectors/side of floppy disk "partition".
I don't rely on this since this is not reliable, these boot sectors are lying most of time.

And yes, the emulator don't increase the file image size on the usb stick if you format the image with more tracks that the file image size can contains.

[tzok]

And yes, the emulator don't increase the file image size on the usb stick if you format the image with more tracks that the file image size can contains.

Ok, that explains everything.