Specifications

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8.3.16
Write
Current
Control
Function
This
routine
sets
+
REDUCE
IW
lignal on
port
C.
bit
6
high.
when
the
cybnder
address
(TRKL
and
TRKH)
is
t
greater
than the
write
cUlTent
switchovcr point
(WRITS~).
See table
8-1.
The
routine'
then
passes
control to
Drive
Seled
LED
Monitor.
8.3.17 DrIve
Select
LED
Monitor
This
function
checks
port
0.
bit
7
(+
SEl).
to
see
If
It
is
high:
Indicating
that
the
drtve
Is
selected. U
it
Is.
bit
3
in
BKPC
(port
C Backgroung
Bit
Control)
Is
set
high.
If
+
SEL
is
low,
then
bit
3ln
BKPC
is
set
low.
See
table
8-1.
Control
now
proceeds to
the
next
routine.
8.3.18
Background
Code
End
This routine
merely
jumps
to
the
beginning
of
Spindle
Motor
Background,
continuing
the background
loop.
8.4
SYSTEM
IN_TIALIZA
TION
TASKS
System
initialization
tasks are performed
only
once
for
each microprocessor
restart. Once
most
initialization
tasks
are completed.
the
foreground
interrupts
are started and control
I.
given
to the
continuous background loop.
Re-
maining initialization
tasks
are
completed
in
the background
loop and make use of
its
time
(as
gated
in
the
foreground)
to
time
necessary
events.
These
initialization
tasks
consist
of:
a. Setting up the
miaoprocessor
internal
registers
and
placing
the
various input and output pins
of
such
into the
proper
initial
state.
b.
Clearing the drive fault latch.
c.
Applying
power
to the spindle
motor
and
verifying
that
It
begins to
rotate
properly.
"
8·91
8·10 (blank)