IBM 7090 Instruction-Reference page 61

Example 2
Signs Unlike, AC Smaller
7 + (-6)
=
+ 1
+0111 SR(7)
-1001 l' s comp of AC (6)
-0000 Q carry
1 Add one
-0001 Result in AC
+0001 Change sign
Add Magnitude
Example 3
Signs Unlike, AC Greater
6 + (-7)
=
-1
+0110 SR(6)
-1000 l' s comp of AC(7)
-1110 No Q carry, Result in AC
-0001 Comp AC
ADM +0401 (I, E) Figure 5.3-15
For this instruction, the word at the storage location indicated by the address is to
be considered positive. This positive word is added, algebraically, to the contents of
the AC. ADM operates the same as ADD, except that the sign of the word is set posi-
tive after it has entered the SR.
Subtract SUB +0402 (1, E) Figure 5.3-15
This instruction algebraically subtracts the word at the storage location indicated by
the address from the contents of the AC. The execution of SUB is similar to ADD,
except that the sign of the word in the SR is inverted.
Subtr act Magnitude SBM -0400 (I, E) Figure 5.3-15
For this instruction the sign of the storage word indicated by the address is considered
negative. This negative word is added algebraically to the contents of the AC. The
execution of SBM is the same as ADD, except that the sign of the SR word is forced
negative.
Add and Carry Logical Word ACL +0361 (I, E) Figure 5.3-16
This instruction adds the 36-bit logical word stored at the location indicated by the
address to the contents of the AC(P-35). AC(S) is ignored; AC(Q) is unchanged. A
carry out of AD(P) is added to position 35 in the adders. The operation of this instruc-
tion is the same as ADD, except for the handling of the (S), (Q), and (P) positions.
Multiply
MPY +0200 (Min I, E) Figure 5.3-17
(Max I, E, 12L)
This instruction multiplies the word stored at the location indicated by the address
by the contents of the MQ. The 35 most significant bits of the 70-bit product replace
the AC(1-35), and the 35 least significant bits replace the MQ(1-35). Positions (Q)
and (P) of the accumulator are cleared, and the signs of the AC and MQ are set to the
algebraic sign of the product.
00 0110 Multiplicand (SR)
1011 Multiplier (MQ)
0110 Partial Product
0110
" "
0000
"
"
0110
" "
1000010 Product (AC and MQ)
60