anil@cyb-eng.UUCP (Anil Patel) (03/08/85)
According to the DOS 3.00 Technical Reference Manual, the Find Next
Matching File system call (0x4F) requires that the DS:DX register pair
point to the information that was passed back to you from the Find First
Matching File system call (0x4E).
Well, if you peruse the DOS 2.10 DOS Technical Reference Manual, you will
notice that the DS:DX register pair does not need to be set up to point to
this same information. Rather, the information is stored in the address
pointed to by the current disk transfer address.
This seemed a bit odd at first, the fact that IBM would change the
parameters to the function call from one version to another. This would
have made many programs that use this function call incompatible between
the two different versions of DOS.
The information in the DOS 3.00 Manual is, however, incorrect. The DS:DX
register pair does not need to be loaded with this information, but the
older style of addressing is still in force. That is, the current DTA must
still point to the information passed from the Find First Matching File
system call.
I have verified this discovery by looking through disassemblies of both the
DOS 2.10 and DOS 3.00 system kernels.
Cheers,
Anil Patel Cyb Systems, Austin, TX
{gatech,ihnp4,nbires,seismo,ucb-vax}!ut-sally!cyb-eng!anil