Sage II - Page 18

SAGE Ir SERVICE
I,IANUAL
I
I
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POWER-UP
ROIJTINE
INITIAI,IZATION
VII.Ol
INITIALIZATION
:
First all
the T/O chips
are initialized
to an
"idle"
condition.
CHECK
THE DATA
SIGNALS:
0000
then
FFFF are writcen to
FCOFFE repeatedly for
about
100 msec.
This is long
enough to use an
oscilloscope to
verlfy
that
all
of
the
data lines are lndeed
going
high and low.
A
llne that does not
change
is ln
error. Check
for
shorts
to another llne or
a
bad
buffer/driver.
If
tr^/o lines are
shorted together
o
the signal may stlll
change but the
level
of the signal
will be too low.
CHECK
THE
ADDRESS
SIGNALS:
Another loop
toggles all the address lines
between
0
and
1
sequentially
reading
addresses
000000,
FFCOFE and
TFFE
for
100 msec.
CHECK THE
Il
O CHIP SELECTS:
hy
A
thir:d
loop
sequentially reads all the
I/O
ports
(
FFC001
,
FFCO11.."FFC081).
Use
an oscilloscope to
verify
that
all the
chip
select
lines
change. The test repeats
for
about
100
ms.