huehn@geac.com (Robert Huehn) (05/30/91)
A while ago someone reported that DR DOS v5.00 masks off the top bit
of partition types - unfortunately it recognizes Minix partions as
DOS partitions. I didn't like this either, since one of my Minix
partitions would probably get trashed eventually.
It seems this was added as a "fix" to allow partitions with the high
bit set to be used:
8a 44 04 mov al,4[si] ;get system ID
24 7f and al,7fh ;clear top (secure) bit
3c 01 cmp al,DOS20_ID;is this a DOS 2.x partition?
(This is from the disk driver source, part of the ROMDISK SDK)
Patching this is simply requires changing the 7f in that byte pattern
to ff, in IBMBIO.COM. I did this last night and didn't see any side
effects. (IBMBIO.COM is compressed significantly after it is
generated, but still seems to work fine after patching it).
--
Rob Huehn (huehn@geac.com) 3A Comp Eng, University of Waterloo