[comp.sys.ibm.pc] Read and Write 720K disks in a 1.2M drive in an AT

henkp@nikhefk.UUCP (Henk Peek) (01/17/88)

In article <352@westmark.UUCP> dave@westmark.UUCP (Dave Levenson) writes:
->In article <63200021@convexe>, loafman@convexe.UUCP writes:

->> /* Written  9:41 am  Dec 29, 1987 by tim@doug.UUCP in comp.sys.ibm.pc */
->> /* ---------- "High density drive in AT (not quad)" ---------- */
->> >    I am approaching my frustration limit w.r.t. trying to read and write
->> >    to high-density disks on my quad-density (96tpi) drive.  While I
->> >    get no error writing to hd disks, they can not then be read on
->> >    various xt's about.

->Quad-density (720 kbytes / diskette) is not compatible with either
->High Density (1.2 Mbytes / diskette) or Double Density (360 kbytes /
->diskette).  The AT-compatible High Density drives and controllers are
->capable of writing either HD or DD format, but not QD format. 

HD drives can write QD (720K) format. Only PCDOS and MSDOS does not
support it. A few months ago, after a long discussion, there was posted
the public domain program intrcpt.asm written by Stanford J. Zelkovitz.
It intercepts some DOS internals and works with PCDOS 3.2 and 3.3.
I use it to read and write QD disks on a commodore PC40 (AT).
(Only formatting QD disk goes wrong in the commodore, but I format
QD disks at home on a XT compatible).

Henk Peek  ..!uunet!mcvax!nikhefk!henkp.UUCP