Customer Engineer's Test Panel; Indicators - IBM 7090 Instruction-Reference

card enter storage location zero, one, and two. The word entered in address zero
should be a control word. When the word counter goes to zero, the channel asks for
another control word from location zero. The CPU gets its next instruction from loca-
tion one.
Load Tape Key (Figure 6.1-13)
The load tape key works the same as the load cards key, causing a reset to the CPU
and all channels not in manual status. The load tape key also causes a read select of
tape unit 1 on channel A, IOCP word count of 3. The next command for the channel will
come from location zero, and the next instruction for CPU will come from location
00001.
Sense Control
There are two types of sense controls on the operator's panel: sense lights and
sense switches. The conditions of these sense devices may be checked by machine
instructions and used to control program flow.
The four sense lamps on the panel may be turned on or off by instructions in the
main program and then checked by the sense instructions. The condition of the lamp
determines if the program steps are to be skipped.
The six sense switches may be set on or off from the operator's panel. The
condition of the switch may then be checked by sense instructions in the program to
determine whether to skip the following program step.
6.2.00 CUSTOMER ENGINEER'S TEST PANEL
In addition to the indicators and manual controls on the operator's panel, the
customer engineer has at his disposal the indicators and controls on the customer
engineer's test panel.
The indicators provide a means for checking the address register contents, the
tally counter, various test triggers, and the cycle time. The switches and jacks
provide means to continually execute any instruction, control 1-0 operation, control
B time, and step through instructions cycle by cycle.
Figure 6.2-1 shows the layout of indicators and controls for this panel and
designates system page locations.
6.2.01 Indicators
Indicators on the customer engineer's test panel are of the incandescent type.
Indicators connected to test triggers are on when the trigger is on and off when the
trigger is off. Indicators concerned with the registers and counters signify a 1
when they are on and a 0 when off.
Address Register
The address register contains the address portion of the instruction under
execution.
158