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From: davis@clocs.cs.unc.edu (Mark Davis)
Newsgroups: comp.sys.ibm.pc
Subject: Please Help with DOS IOCTL Return Codes
Summary: Does 05h mean for Int 21, Func 44, Sub 0D, Func 40
Keywords: DOS INT_21 IOCTL Return_Codes
Message-ID: <7211@thorin.cs.unc.edu>
Date: 13 Mar 89 14:38:48 GMT
Sender: news@thorin.cs.unc.edu
Reply-To: davis@cs.unc.edu (Mark Davis)
Organization: University Of North Carolina, Chapel Hill
Lines: 46

I am trying to use DOS IOCTL calls for block devices and I am getting
undocumented error codes:
	INT 21,
	AX=440D,
	CH=08 (disk),
	CL=40 (set device parameters).
On return:
	carry Flag=set (error)
	AX=05h (Not listed that I can find)

This program is running on a PS 2 Mod 60 using PC/DOS 3.3.  The logical
disks in question are controlled by the standard PS 2 MFM controller:

Disk number	3	5	4	6	7
Disk letter	C:	E:	D:	F:	G:
Located on a	-ST 4053 -	---- ST 4096 -----

The only return codes listed in the all of the references I can find
are
AX=01h == Bad Command
   02h == Invalid Disk

Both of the disks start out as type 32 (ST 4053).  I am trying to fix
the number of heads for the 4096 and the resulting number of cylinders
in each partition.

When I use CL=60 (to get parameters), there is no error.  But, when I
use CL=40, I get an error (carry set) and AX=05h.  The set parameters
seems to kind of work otherwise.  For example, FORMAT can figure out
the correct disk geometry after this call.  The DOS Disk parameter
block valid byte gets set to F8h after the call (FFh means invalid).

Questions:

1. Does anybody know what the rest of the return codes are.  In
particular, what does AX=5 mean?

2. I seem to remember a recommendation for a book titled something like
"Developers guide to MS DOS" by Microsoft, but I can't confirm the
existence of such a book.  Does anybody know for sure.  An ISBN or MS
product number would be wonderful.

By the way, it is possible to make a PS 2 Model 60 use an ST 4096.
More details to follow.

Thanks - Mark (davis@cs.unc.edu or uunet!mcnc!davis) (919)962-1739