On Tue, Nov 18, 2003 at 01:41:02PM -0500, J.C. Wren wrote:
> 6502:
> Commodore DOS (not sure of the name)
Commodore DOS didn't really have a name, largely because it was never
a standalone product. It was built into ROM on all disk devices that
implemented it. BASIC 4 machines (PET 8032, PET 4032, etc.) had some
extra commands (compared to BASIC 2 machines, and the C-64 and VIC-20)
that took care of some of the details, but the traffic between the
computer and the drive was identical...
For example:
On a BASIC 4 PET, you could type CATALOG to get a disk catalog. On
all machines, including BASIC 4 machines, you could load the special
file "$" to get a catalog (i.e., "LOAD "$",8").
The drive itself knew about the directory format, media capacity,
what a sequential file was, etc. The PET/C-64/VIC-20 just knew
how to open a device (printer, disk drive, modem, etc.), how to
move blocks back and forth, and how to close the device.
It's a very different model than most computers use. There was no
real "DOS" on the CPU, just low-level device access routines.
There are DOS version numbers for devices, but they tend to be related
to how new the drive is, and any details about media and capacity. I
know of only one "upgrade" in the Commodore drive family - the original
2040 drives had a slightly buggy DOS for which a new set of ROMs
were available, making it, in effect, a 4040 drive (the low-level format
changed slightly, eliminating one block per track for one of the recording
zones). There were version numbers like 1.0 and 2.0 for the 2040/3040/4040,
up to 3.0 for devices like the D9060 and D9090 hard drives.
It's probably too much detail for what you want, but the Commodore drive
scheme isn't like the other microcomputers of the day, and it bears
some explaining.
-ethan
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Received on Tue Nov 18 2003 - 16:45:28 GMT