17 May
2023
17 May
'23
3:35 a.m.
On 5/16/23 18:57, Fred Cisin via cctalk wrote:
On some controllers, DTC BXD06 BIOS for example, another DOS 2.x option
was available. One could split a 32MB drive into two 16MB drives, each
with a different BIOS (0x80 and 0x81) address.
In the days of 16 bit sector addresses, disks got larger than PCDOS's
ability to service them. One way around this was to incorporate a
software shim in the BIOS to block 512 byte physical sectors into larger
multiples (e.g. 1024, 4096, 8192...bytes). DOS could deal with this at
the expense of more memory consumed for buffers, but it worked, sort of.
Another option used was to address the disk via a network redirector,
which accessed files by name, not absolute sector.
All mostly forgotten today.
--Chuck
>> The
biggest drive I remember seeing on OS/9 was 20MB or 40MB. I
>> don't remember the File Allocation Table size or format.
> Well, that would be "spot on", as the formatted capacity of an ST-251
> was
> 40 Megabytes.
>> When used with MS-DOS, prior to
> MS-DOS 3.31, it would be partitioned as
>> two 20MB, or as a 32MB plus an 8MB.
>> (V3.31 was the first version of MS-DOS to support a partition larger
>> than
>> 32MB)