[comp.sys.ibm.pc.programmer] INT 25 for >32MB Partitions

feg@floyd.ATT.COM (Forrest Gehrke,2C-119,7239,ATTBL) (06/17/91)

I am having difficulty trying successfully to code in
C an absolute disk read using the alternate (extended)
method for INT 25 required for reading into a disk
partition greater than 32MB.

Particularly, my problem is with the disk read packet
DS:BX which requires (and here I am quoting from
Ralf Brown's INT291 listing for this INT):

00h DWORD Sector Number
04h WORD Number of sectors to read
06h DWORD Transfer address

Sector number: is this the absolute sector number starting
from the partition sector, or is it the DOS boot sector?
If accessing the boot sector is this number 0?

Transfer Address: To where?  How is this address chosen?

If anyone has coded this successfully in C I would appreciate
receiving via email the code fragment involved.

Thanks,

--Forrest Gehrke feg@dodger.att.com