[Coco] VCC & Drivewire using new disk image
robert.gault at att.net
Thu Jun 16 15:36:58 EDT 2016
Salvador Garcia via Coco wrote:
> What does DISKINI0 do to the floppy disk image? Does it basically write out the system sector on track 17? Thanks! Salvador
A raw disk could easily be random garbage or blank/empty. Drivewire does not
perfectly emulate hardware, so you can mount a zero byte file.
The command DSKINI# tells the disk controller or software like Drivewire to
initialize the disk so that it can be used. On hardware that means placing
special track/sector headers on the disk and making all data bytes of each
sector some special value. Disk Basic make each byte = $FF.
By default, Disk Basic will generate a single sided, 35-track, 18 sectors per
track disk. Look for details in "Color Computer Disk System Owners Manual &
In addition to the above, the Disk Basic software needs to read the disk and
that means the directory track of the disk needs to be initialized. T17S2 the
file allocation sector will be set to $FF for as many bytes as needed to cover
the number of track/sectors on the disk. So bytes 0-$43 will be $FF and the rest
$44-$FF will be $00 with a 35 track disk.
The sectors T17S3-T17S18 will be all $FF until files are saved where 32 bytes
will be used for each file on the disk. The first 16 bytes are used by Disk
Basic with the second 16 bites all $00. EDTASM+ uses all 32 of the bytes.
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