IBM 7090 User Manual

To test for a zero condition, the accumulator is complemented to the adders, and a one
is added to position 35. If a zero condition exists, a carry results which ripples through
all of the adders and turns on the Q carry trigger. The Q carry trigger is used to condi-
tion the transfer circuits.
Transfer on No Zero
TNZ -0100 (1, L)
Figure 5.3-29
If the contents of the AC are not zero, the next instruction is taken from storage lo-
cation X. If the contents are zero, the computer proceeds to the next instruction in
sequence.
Transfer on Low MQ
TLQ +0040 (I, L)
Figure 5.3-30
An algebraic comparison is made between the MQ and the accumulator contents. If
the MQ contents are less than the accumulator contents, an instruction transfer is
made to storage location X. If the MQ is greater or equal, no transfer is taken. For
this instruction a +0 is considered to be larger than a -0. The contents of both registers
are left unchanged.
The operation is performed by adding the contents of the MQ to the complemented
accumulator contents. The Q carry trigger is then matched with the re.gister signs to
determine whether the conditions for transfer have been met. To prevent transfers
when the factors are equal, a one is added to AC(35) to produce a Q carry when the AC
factor is plus.
The following table illustrates comparisons which might be made, along with the
desired result:
No. in AC
No. in MQ
Q
Carry
Transfer
-7
-6
No
No
-6
-6
No
No
-0
-6
Yes Yes
-0
-0
No
No
+0 -0
Yes
Yes
-0
+0
No No
-6
+6
No
No
,-0
+6
Yes
No
+6
+6
Yes
No
+7
+6
No Yes
Transfer on Channel in Operation
TCO +XXXX (I, L)
Figure 5.3-31
This instruction causes a transfer to storage locaqon X if the particular data channel
is in use. Operation codes +0060 through +0067 are used to check data channels A through
H, respectively.
Transfer on Channel Not in Operation TCN -XXXX (I, L)
Figure 5.3-31
TCN causes a transfer to storage location X if the data channel is not in operation.
Operation codes -0060 through -0067 are used to select data channels A through H,
respectively.
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IBM 7090 Specifications

General

Category	Mainframe Computer
Introduced	1959
Transistor-based	Yes
Word Length	36 bits
Add Time	4.8 microseconds
Memory	Core memory
Memory (words)	32, 768 words