On Tue, 5 Nov 2019, rescue via cctalk wrote:
However, when I do a format a:, the drive will format through the 40 tracks,
then instead of the heads returning to track 0 quickly, they do these small
stepping 'bursts' and DOS times out saying failure..... it probably would
have worked if DOS would wait 10 seconds or more for the drive to move to
track 0.
Which version of DOS are you using?
Slight variation, . . .
IBM used Qumetrak 142 (half-height 5.25") on the PCJr and "Portable PC"
(similar to Compaq) It is a SLOW stepping drive.
One of the differences between PC-DOS 2.00 and 2.10 (released at that
time) is that 2.10 has a much longer stepping time. The previous
stepping time by default in PC-DOS 2.00 was not long enough for the
Qumetrak 142 to step. Getting the step pulses too quickly caused it to
miss some of them.
Consider building a different table in memory, and repointing Int1Eh at
the new table.
BTW, MS-DOS 2.11 is one of the versions of MS-DOS that has a lot of OEM
customization. For example, IBM didn't support 720K until PC-DOS 3.20,
but there were a number of MS-DOS machines that started using 720K at
2.11 Gavilan's 3.5" format didn't match the one that IBM went with
until Gavilan MS-DOS 2.llK
(The other MS-DOS version with a lot of customization is 3.31. For
example, support of drives larger than 32MB)
