Browse Prior Art Database

Auto Media Sense

IP.com Disclosure Number: IPCOM000116804D
Original Publication Date: 1995-Nov-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Bland, PM: AUTHOR [+10]

Abstract

Most Floppy Disk Controllers in the IBM PC Compatible space automatically turn the floppy motor on when they request media id information from the drive. This is not a problem for Operating Systems that only read media sense when a diskette is put into the drive. However, now that multiple Operating Systems are being ported to run on the same platforms, other cases must be handled. There are Operating Systems, like Apple System 7, that do media sense operations several times per second, because they historically used Floppy Controllers that do not report when media is being inserted, so they need to read the drive often to detect media changes.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 65% of the total text.

Auto Media Sense

      Most Floppy Disk Controllers in the IBM PC Compatible space
automatically turn the floppy motor on when they request media id
information from the drive.  This is not a problem for Operating
Systems that only read media sense when a diskette is put into the
drive.  However, now that multiple Operating Systems are being ported
to run on the same platforms, other cases must be handled.  There are
Operating Systems, like Apple System 7, that do media sense
operations several times per second, because they historically used
Floppy Controllers that do not report when media is being inserted,
so they need to read the drive often to detect media changes.  This
presents a problem when the Operating System is ported to a platform
that uses a standard PC Compatible Floppy Controller, because it
would constantly be turning the floppy motor on and off.

      This invention solves the problem by de-coupling the motor
enable lines (MTR0* and MTR1*) between the Floppy Controller and the

Floppy Drive through two tri-stateable buffers (F125's).  The output
enables to the buffers are controlled via software:  A bit in a
control register has been defined, called MOTOR_EN*, that software
can turn on and off.  The setting of this this bit flows out of a
chip and connects directly to the output enables of the F125 buffers.
The outputs of the buffers are pulled up to 5 Volts with 10K
resistors, so that when the buffers are tri-stated (i.e., the
software bit...