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keirf / flashfloppy

Floppy drive emulator for Gotek hardware
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Problem of head selection on Thomson computer #945

Open Neo2003 opened 2 weeks ago

Neo2003 commented 2 weeks ago

Hello, Playing with flashfloppy on Thomson computer, I was able to convert sap images to edsk images and use all the 1 sided 320ko floppy images. Thomson are using 16 sectors of 256 bytes, 80 tracks. This computer also supports double-sided floppy disk, but it does use the floppy as 2 independent sides. So it reads side 0, then side 1. The Thomson controller is a THMFC1. My problems begins when I switch to 2 sided images. Whatever I create a edsk with 2 sides or just create a mapping to the images, it does not work. The Gotek switch to side 1 while the computer still expect to see only side 0, then it crashes. 2 sides edsk or this definition lead to same problem. fd files are just stupid sector contents of full side 0, then full side 1 sequentially.

[fd::655360]
file-layout = sequential
cyls = 80
heads = 2
interleave = 7
secs = 16
bps = 256
gap3 = 27
tracks = 0-79.0
  id = 1
tracks = 0-79.1
  id = 1

Instead of reading 0.0, 1.0... the Gotek switches to 0.1 after 0.0 while it should not. The floppy disk drive used on this computer is this one https://bitsavers.trailing-edge.com/pdf/sony/floppy/9-975-176-01_MP-F53W_Product_Specifications_Sep85.pdf

Is this paper it is stated: 3-3-4. HEAD SELECT A true (low) level on this input will cause Head 1 (upper) to be selected. A false (high) level on this input will cause Head 0 (lower) to be selected. If the HEAD SELECT signal changes during either a write or erase operation, the head will not change until both the ERASE GATE and the WRITE GATE signal become false (high).

So can you please guide me on how to make the gotek not switch to side 1 when it should not. Tested version 3.42 and 4.06a

Neo2003 commented 2 weeks ago

Found a workaround by forcing to go back to head 0 if on head 1

[fd2::655360]
file-layout = sequential
cyls = 80
heads = 2
interleave = 7
secs = 16
bps = 256
gap3 = 27
tracks = 0-79.1
  h = 0

But trying to do the same with dsk does not work like if it was ignored.

keirf commented 2 weeks ago

CPC DSK files contain the sector headers so don't use the IMG.CFG definitions. Those definitions are only used for raw sector images (eg. IMG).

Neo2003 commented 2 weeks ago

Ok, so maybe correct the IMG.CFG file.

  1. matches images of the form *..{img,ima,dsk}

I am still search why it moves to head 1 after a track on head 0 is read, when I make a dske with Thomson TO8 disk or when I use a .fd with the IMG.CFG without h=0