🚀 go-pugleaf

jamesm@procor.dialogic.com (Mark James) writes:

>This may be a FAQ (in which case someone kindly point me to where it's
>dealt with), but I've started to use DOS 5 for the first time and have
>run into what I suppose is the four-byte sector number problem.  Programs
>that use INT 24h and INT 25h for absolute sector reads and writes no
>longer work.  Would someone please post (or send me by E-mail) the
>following:

>1.  What's different in the use of the absolute sector INTs?

>2.  What (if anything) is different in boot sector information?

>3.  Has anything else changed that I should know about?

>4.  Is this *exactly* the same problem that Compaq's MS-DOS 3.1 had, in
>    about 1987, with their first 300MB disks?

I think you mean INT 25h/26h, not 24/25.

The rules of the game are that if you are talking to a partition
larger than 32 MB you must use the new INT25/26 parameter list, even
if you need access to a sector at the front of the partition.  I don't
know if it's bulletproof but where I've needed absolute access to a disk
I use the new parm list format if DOS version > 3.3.

I haven't any idea what problems Compaq had in 1987.  We probably had
a few hundred of them here at the time but I don't recall having heard
anyone complaining ... although few users had 300 MB disks then.

For more info, see the MS-DOS Programmer's Reference (MS Press, US$25 list)
and/or Ralf Brown's interrupt list (US$0.00, on your favorite archive server).

Joe Morris