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the Set IC trap, the CPU again enters
the wait state.
If a system. reset had occurred prior
to pressing the Set IC key, the micro-
program starts at address 0000.
This
causes the UCW'S to
be
cleared prior to
setting the instruction counter from the
switches.
STORE :KEY
•
•
•
Loads the byte specified by the Data
Switches (H and
~
into the area
specified by Display-Store Selection
Switch (E).
Store key is inoperative if the CPU
clock is running.
The Store key is located on logic
page PA 111.
Description
Pressing the store key gates the con-
tents of switches Hand
J
into the B-
register.
TheB-register is gated high
and low through ALU.
The resultant data
byte appears on the Z-bus and is gated
to the area selected by switch E.
If a
register is selected to receive the data
byte, the Z-bus is gated directly to the
selected register.
If memory is
selected to receive the contents of H
and J, the Z-bus is gated to the R-
register.
In the case where memory is
selected by switch E. switches A, B, C,
and D provide the memory address, and a
manual read cycle and a manual write
cycle are taken to place the data byte
from switches Hand
J
(now in the
R-register) into the desired address.
The CPU clock mUst be stopped, and
the allow write latch m.ust be off for
the store operation to take place.
CHECK RESET KEY
•
Resets the machine check register as
well as several machine check
control latches to the no error
state.
•
Check reset may occur with the CPU
clock running or stopped.
•
Check reset key is located on logic
page PA 111.
Description
Pressing the check reset key resets all
positions of the machine check register
to the no error state.
In addition, the
first machine cheok, the second error
stop, and the check restart latches are
reset.
This means that all machine
check logic is reset.
LAMP TEST KEY
•
Turns on all console indicator driv-
ers.
•
Can be pressed while system is run-
ning.
•
The lamp test key is located on
logic page PA 111.
Description
An additional input is provided on all
indicator driver circuits for testing
purposes.
This input serves an OR func-
tion along with the normal driver input.
When the lamp test key is pressed, all
indicator drivers should turn on to
light all console panel lights.
START KEY
•
The start key starts the CPU clock.
•
System operation depends on what
conditions exist when the start key
is pressed.
•
The start key is located on logic
page PA 101.
Description
If the start key is pressed after a
normal stop (for example, if the stop
key had been pressed), instruction proc-
essing continues as if no stop had
occurred.
Machine status is not affect-
ed.
If the start key is pressed after a
system reset, the machine reset latch
forces the address 0000 into WX.
This
causes the microprograrr to start at the
ucw
clear routine.
Other traps are then
allowed to occur in the order of their
assigned priority.
6-13
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