North Star RAM-16-A Manual page 17

memory test program to verify correct operation of the
board. If you do not have a memory test program (such as
the TM command in the North Star Monitor), then use the
program listed in Appendix 2.
If the RAM-16-A does not fail the memory test after several
hours of operation, then the board is operational and you
may skip the remaining checkout steps.
or addressing errors are detected, then refer to the
schematic drawings to diagnose and correct the problem.
(The correspondence between addresses and RAM chips is given
in Appendix 3.)
then continue with step C3.
C 3 . Set the address switches labeled "2" and "3" on the DIP
switch (2nd and 3rd from the top) to the "ON" position.
other six switches should be OFF.
off, install ONLY the processor board and the RAM-16-A into
the computer motherboard.
hold down the computer reset switch so that no memory
requests are being made.
A. Check the following memory cycle request signals while the
computer reset switch is depressed:
Signal
STORE/
INSTRUCTION-FETCH/
FETCH/
RUNNING-REFRESH/
DEPOSIT-CY/
If the signals are not as listed then refer to the schematic
drawings and trace backwards to locate and correct the
problem.
B. WAITING-REFRESH cycles should occur approximately every 25
microseconds.
period of PHI 2 in your computer
processor and 500ns with a 2MHz processor).
following signals while the computer reset switch is
depressed:
Signal
WRF
WAITING-REFRESH/
CYCLE-START
delay tap T1
delay tap T2
delay tap T3
delay tap T4
If the RAM-16-A does not operate at all,
Turn on the power and depress and
Location
4B pin 5
4B Pin 11
4B pin 6
6C pin 6
4B pin 4
In the following table, let T refer to the
Location
2A Pin 3
1C pin 12
4B pin 8
5A pin 12
5A pin 4
5 A pin 10
5A pin 6
North Star 16K RAM Board
If systematic data
With the computer power
Description
HIGH
HIGH
HIGH
HIGH
HIGH
(e.g., 250ns with a 4MHz
Check the
Description
(+T i ,25us)
AC,
AC, (-T i ,25us)
(+T, ,25us)
AC,
AC , ( + T , , 25us)
(+T, ,25us)
AC,
(+T, ,25us)
AC,
(+T, ,25us)
AC,
The
16