IBM 7090 Instruction-Reference page 103

To execute this instruction, an E cycle is required to bring the word in storage to
the storage register; then an L cycle is used for two comparisons in the adders. For
the first comparison, the SR and the complement of the AC are fed to the adders; the
Q carry and sign conditions are matched to condition the first possible skip. The sec-
ond comparison is made after a one has been added to the difference, to differentiate
words of equal magnitude.
The following illustrate some of the possible combinations:
Number in Number in
Q Carry Tgr
Accumulator Storage 1st Comp
2nd Comp Result
-6
-7 On On Next Instruction
-6 -6 Off On Skip 1 Instruction
-6 -4 Off Off
Skip 2 Instructions
-6 +6 Off
On Skip 2 Instructions
-0 +0 Off On
Skip 2 Instructions
+0
-0 Off On Next Instruction
+6
-6 Off On Next Instruction
+6
+4 Off Off
Next Instruction
+6
+6 Off On
Skip 1 Instruction
+6 +7
On On Skip 2 Instructions
Logical Compare Accumulator with Storage
LAS -0340(1, E, L) Figure 5.3-37
This instruction compares the contents of the AC(P, 1-35) with the logical word (S, 1-35)
stored at location X. The sign of the AC is disregarded; the contents of the AC and
storage are unchanged.
If the contents of the AC are greater than the contents of storage location X, the
computer takes the next instruction in sequence. If the AC equals storage, the computer
skips one instruction. If the contents of the AC are less than the contents of storage,
the computer will skip the next two instructions.
This instruction is executed the same as CAS, except that the signs are not used for
an algebraic comparison and AC(P) is compared against SR(S).
Plus Sense
PSE +0760 ... XXXX(I, L)
This instruction provides a means to test the status of any of the six sense switches,
to turn on or off the four console sense lights, and to permit the transmission of an
impulse to or from the exit or entry hubs of either the printer or punch.
The address portion of the instruction determines whether a light, switch, printer,
or card punch is being sensed; further, it determines' which light, switch, or hub is
being sensed. The octal addresses for the different sense instructions are:
Address
0140
0141-0144
Instruction
Turn off all sense lights (Figure 5.3-38)
Turn on sense light 1, 2, 3, or 4, respectively (Figure
5.3-39)
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