Browse Prior Art Database

PS/2 5-1/4" 360KB/1.2MB External Diskette Drive

IP.com Disclosure Number: IPCOM000108511D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 56K

Publishing Venue

IBM

Related People

Heisch, RR: AUTHOR

Abstract

This invention provides the ability to access both 360KB and 1.2MB diskettes on an IBM PS/2*. Today, the IBM External 5-1/4" Diskette Drive for the PS/2 can only support 360KB diskettes due to the inability of the PS/2 hardware to access the diskette drives using a 300Kbit/second data rate. This rate is required to access 360KB diskettes in a 1.2MB drive and is the solution used by the IBM PC AT*. Since the PS/2 series does not provide this data rate, it can only support either a 360KB drive or a 1.2MB drive (that cannot access 360B diskettes). This is an unfortunate situation since there is a large quantity of both 360KB and 1.2MB diskettes containing both programs and data that cannot be accessed from the IBM PS/2 systems.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 58% of the total text.

PS/2 5-1/4" 360KB/1.2MB External Diskette Drive

       This invention provides the ability to access both 360KB
and 1.2MB diskettes on an IBM PS/2*.  Today, the IBM External 5-1/4"
Diskette Drive for the PS/2 can only support 360KB diskettes due to
the inability of the PS/2 hardware to access the diskette drives
using a 300Kbit/second data rate.  This rate is required to access
360KB diskettes in a 1.2MB drive and is the solution used by the IBM
PC AT*.  Since the PS/2 series does not provide this data rate, it
can only support either a 360KB drive or a 1.2MB drive (that cannot
access 360B diskettes).  This is an unfortunate situation since there
is a large quantity of both 360KB and 1.2MB diskettes containing both
programs and data that cannot be accessed from the IBM PS/2 systems.

      This invention describes the necessary modifications to a 1.2MB
diskette drive that will allow it to access both 360KB as well as
1.2MB diskettes from an IBM PS/2.  The 1.2MB drive owes its increased
density from a 360KB drive to double density tracks as well as a
faster rotational velocity (360RPM instead of 300RPM).  It is
therefore necessary to read the data on a 360KB diskette in a 1.2MB
drive at 300Kbits/second in order to access the data (which was
originally written at 250Kbits/second on a 300RPM 360KB drive).
Since this data rate is not available on the IBM PS/2, another
solution is required.

      The solution described here is to operate the 1.2MB drive at
va...