RANA Systems Elite Controller, User Manual

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ELITE SERIES USER MANUAL APPEN. C - CP/M NOTES
C . 4 . 6 5 0 2 R W T S A l t e r a t i o n s
The calling protocol is unchanged for the 6502
RWTS disk drivers. The only difference is that
sector numbers from 16—31 will result in the
enhanced RWTS trying to access the second head
on the drive, which would only be effective for
the Elite Two and Elite Three. Also, a request
for drive 3 or 4 will cause the RWTS to try to
access the second hank of an Elite Controller
regardless of the controller card in use. This
will result in reselecting drive 1 or 2 on a
Disk II controller without the software really
being aware of the difference.
When the RWTS attempts to determine the seek
rate to use on the drive, it takes the slot*16
and drive values it was given and scans the
drive map table in the BIOS to determine the
logical CP/M drive being accessed. It then uses
this logical drive number to index the seek
configuration table. This is the reason for
supplying seek configuration tables with entries
for all 16 possible drives, even though CP/M
itself is only supplied with 8 drives worth of
DPH’s.
Under normal use, the drive mapping table would
not be altered dynamically by a user (transient)
program; but if for some reason it is, then the
program doing the altering must keep in mind how
the RWTS seek drivers index the tables (as ex-
plained above).
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