Bypassing Bios; Diskette Drive Controls - IBM AT 5170 Technical Reference

• Diskette drive controls
• Write current control
Bypassing BIOS
Copy protection that tries to bypass the following BIOS routines
will
not work on the High Capacity Diskette Drive:
Track Density:
The High Capacity Diskette Drive records tracks
at a density of 96 TPI (tracks per inch). This drive has to
double-step in the 48 TPI mode, which is performed by BIOS.
Data Transfer Rate:
BIOS selects the proper data transfer rate
for the media being used.
Disk Base:
Copy protection, which creates its own disk base
will not work on the High Capacity Diskette Drive. ­
Diskette Drive Controls
Copy protection that uses the following
will
not work on the High
Capacity Diskette Drive:
Rotational Speed:
The time between two events on a diskette is
controlled by the Fixed Disk and Diskette Drive Adapter.
Access Time:
Diskette BIOS routines must set the track-to-track
access time for the different types of media used on the ffiM
Personal Computer AT.
Head Geometry:
See "Diskette Drive Compatibility" on page
Diskette Change Signal:
Copy protection may not be able to
reset this signal.
9-6 Compatibility
9-5