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I
-C. -Install a jumper wire at MW (near location 6A) -i.f the MW
trace has been cut.
D. with the computer power off, install" only the ZPB in the
computer motherboard.
E. -Turn on the computer power and
chec~
for the following
signals.
Note that all timing signals given below assume
the ZPB is configured for standard 4MHz
o~eration.
-
Signal
-
Location
-
Description
-
PHI
-
Z80 pin 6
-
-
AC, (+125ns,250ns)
PHI 2
MB pin 24
AC, (+12 5ns , 250n s )
PHI 1
MB pin 25
AC, (+62ns , 25 011s )
2MHZ CLOCK/
MB pin 49
AC, (-25"0ns,500ns)
-If any of these are wrong, -trace back to the crystal -to
determine the cause.
-C2. -This step will check the reset logic.
Use the same setup as
the previous step and check the following signals while
alternately depressing and releasing the computer reset
switch.
-
Switch
Switch
-
Signal
-
Location
Released
Depressed
-
RESET/
MB pin 75
-
-
LOW
HIGH
7G pin
6
HIGH
LOW
-
RST/
5G pin
6 "
LOW
HIGH
POC/
MB pin 99
LOW
HIGH
-
C3.
-
Check the auto-jump logic
follows:
as
A. -Leave the board configured as in the previous
StE~p.
-B. -Turn off the computer power and remove the ZPB from the
computer.
Temporarily connect the PRDY signal to ground by
soldering a piece of jumper wire beween 7F pin 5 and 7F pin
7 on the solder side of the ZPB.
-C. -Install only the ZPB in the computer motherboard and then
turn on the power and depress and release the reset switch.
The processor should pause
im~ediately
after performing the
auto-jump sequence and just before executing the first
instruction at the auto-jump address.
Check that the SMI
signal at motherboard pin 44 is HIGH.
D. Assuming the jump address specified on the header at
location E2 is E800, theq E800 should be on the motherboard
address lines.
HIGH signals should be observed on the
following motherboard pins:
-North Star Z80A PROCESSOR BOARD
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