CIAB
PB7 DSKMOTOR*
Disk motor control (active low). This
signal
is
nonstandard on the Amiga system.
Each drive will latch the motor signal
at
the time its SELn* signal turns on.
The disk drive motor will stay
in
this
state
until the next time SELn* turns on,
at
which time it will latch the new value
of DSKMOTOR*. All software
that
selects
drives should set up the motor signal before
selecting any drives. The drive will
"remember" the state of its motor when
it is not selected. All drive motors
turn
off
after system reset.
CIAB
PB6 DSKSEL3*
Select drive 3 (active low).
CIAB
PBS DSKSEL2*
Select drive 2 (active low).
CIAB
PB4
DSKSELl*
Select drive 1 (active low).
CIAB
PB3
DSKSELO*
Select drive 0 (internal drive)
(active low).
CIAB
PB2
DSKSIDE*
Specify a particular head of
the disk. Zero implies the upper head.
CIAB
PBl
DSKDIREC Specify the direction
to
seek
the heads. Zero implies seek towards
the center spindle. Track zero is
at
the outside of the disk.
CIAB
PBO
DSKSTEP*
Step the heads of the disk.
This signal should always be used as
a pulse (first
low,
then high).
Leaving this line
low
while changing
the SEL lines confuses the change logic
CIAB
FLAG
DSKINDEX*
Disk index pulse
(BFDDOO,
bit
4).
Can be used
to
create level 6 interrupt
Interface Hardware
229
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