DSK disk image files (with file extension *.DSK or *.WTA) are commonly used by
emulators running the TSC FLEX operating system, see:
ReFLEX by Ben Williams,
SWTPC 6800/6809 Emulator by Evenson Consulting Services or
6809 FPGA design by Neal Crook.
Also FLEX software archives use DSK disk image files, see:
FLEX User Group by Ian P. Blythe or
FLEX Software Archive by Simon Wynn Consulting.
A *.DSK file contains all sectors of a disk. A wide range of track/sector
combinations is supported.
Following table shows typical used disk formats:
Disk size [inch] | Sides | Density *) | Tracks | Sectors | File size [KByte] |
---|
5 1/4 | 1 | SD | 35 | 10 | 87.5 |
5 1/4 | 2 | SD | 35 | 20 | 175 |
5 1/4 | 1 | SD | 40 | 10 | 100 |
5 1/4 | 1 | DD | 40 | 18 | 180 |
5 1/4 | 2 | SD | 40 | 20 | 200 |
5 1/4 | 2 | DD | 40 | 36 | 360 |
5 1/4 | 1 | DD | 80 | 18 | 360 |
5 1/4 | 2 | SD | 80 | 20 | 400 |
5 1/4 | 2 | DD | 80 | 36 | 720 |
5 1/4 | 2 | QD | 80 | 72 | 1440 |
8 | 1 | SD | 77 | 15 | 288.75 |
8 | 1 | DD | 77 | 26 | 500.5 |
8 | 2 | SD | 77 | 30 | 577.5 |
8 | 2 | DD | 77 | 52 | 1001 |
**) | - | - | 255 | 255 | 16256.25 |
**) | - | - | 256 | 255 | 16320 |
*) SD = single density, DS = double density, QD = quad density
**) Harddisk
The sector size is always 256 Byte. The size of the
file can simply be computed with <nr_of_tracks> * <nr_of_sectors> *
256 Byte. If the DSK-file is write protected the drive within flexemu is write
protected too.
Optionally a
JVC file header is supported. The header can contain 1 up to 5 bytes.
flexemu supports the following JVC header values:
Byte offset | Description | Default | Supported values |
---|
0 | Sectors per track | - | 5-255 |
1 | Side count | 1 | 1,2 |
2 | Sector size code | 1 *) | 1 |
3 | First sector ID | 1 **) | 1 |
4 | Sector attr. flag | 0 ***) | 0 |
*) A sector size code of 1 means a sector size of 256 Byte
**) For FLEX compatibility the first sector ID always should be 1
***) Sector attribute flag should be 0 (A sector attribute byte is unsupported)