North Star RAM-16-A Manual page 19

drawings to locate and correct the problem.
C5. This step will test the memory fetch and store operations by
forcing the computer to execute alternating RST 7 and
MOV A,A instructions repeatedly.
A. Set the address select switches labeled "I" and "2" on the
nip switch (1st and 2nd from top) to the ON position.
other six switches should be OFF.
B. With the power off, remove the 74LS373 IC from location 17E
of the RAM board.
DI bus.)
C. With a piece of jumper wire, make a temporary solder
connection between 17E pin 15 (DI7) and 5D pin 6 (A0) o' n the
solder side of the RAM-16-A.
D. If the processor board has a PROM option, it should be
disabled for this step.
E. With the power off, install ONLY the processor board and the
RAM-16-A board in the computer motherboard.
F. Turn on the computer power.
RST 7 instruction should fill the entire RAM-16-A board with
alternating bytes containing 3A hex and 00 (resulting from
the stack pushes of the RST instruction).
G. Check the following signals at the memory chip at location
10D:
Signal
Vbb
DI
WE/
RAS/
A0/
A2/
Al/
Vdd
Vcc
A5/
A4/
A3/
CS/
DO
CAS/
Vss
Note 1: Usually four pulses per loop (15T or 16T), two at
Ml leading edges for fetches; two at Ml trailing edges
(This disconnects the RAM-16-A from the
The repeated executions of the
Location Description
10D pin 1 -5V
10D pin 2 mostly HIGH, LOW during first PWR
10D pin 3 AC, two pulses, one during each PWR
10D pin 4 AC,
10D pin 5 AC,
10D pin 6 AC,
10D pin 7 AC,
10D pin 8 +12V
10D pin 9 +5V
10D pin 10 AC,
10D pin 11 AC,
10D pin 12 AC,
10D pin 13 GND
10D pin 14 AC, see note 3
10D pin 15 AC, see note 4
10D pin 16 0V
North Star 16K RAM Board
see note 1
see note 2
see note 2
see note 2
see note 2
see note 2
see note 2
The
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