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BOARD CHECKOUT
The following checkout procedure should be followed for a newly
assembled board.
It can also be used to diagnose problems in
previously operational boards.
This checkout procedure assumes that no other board besides the
ZPB is plugged into the S-100 bus.
This makes it possible to get
the ZPB operational even if no other board in the system is yet
working.
This procedure assumes only that the correct
unregulated voltages have ·been applied to the bus, that the
computer has a reset switch, and that the bus lines are not
shorted to each other.
The following terms are used in specifying expected test results.
GND
LOW
HIGH
+5V
AC
ground, 0 volts DC
logic zero, 0-.7 volts, normally about .3 volts
logic one, 2.4-5.0 volts, normally about
3
volts
+5 volts from power supply
Signal with pulses (as opposed to DC signal)
When referring to the name of a signal from the schematic
drawings, if the signal is identified with a bar over its name
then the name of the signal is followed by a slash (e.g., STORE/)
in the checkout instructions.
When describing an AC pulse, the
notation (±W,P) refers to a positive or negative pulse with a
width of Wand a period of P.
For example, a positive pulse of
width 125 nanosetonds appearing every 25 microseconds would be
represented as (+125ns,25us).
See Appendix 1 for details on how
to detect pulse signals.
The abbreviation MB before a pin number indicates a bus pin on
the motherboard.
If an oscilloscope will be used to test the board, a "scope
ground" may be iristalled by soldering a "bridge" of jumper
~ire
between the two PC board holes that connect edge connector pins
50 and 100 near location 2A.
Note that either of the two
regulator machine screws can also be used for ground test points.
Cl.
Check for correct clock signals on the ZPB as follows:
15
A. Install a jumper wire at PE (near location 4G) if the PE
trace was has been cut.
B. Remove the lW jumper (near location 6G) if it was previously
installed.
North Star Z80A PROCESSOR BOARD
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