Subtract Logical Characters-Slc - IBM 5410 Maintenance Manual

Gate SOR To B
Main S
B
Register
Storage D
~----
R
tlllllllll•-•
Select ORR and LCR
LSR LSR
Hi Lo
Figure 3-15. Subtract Logical Operation-Subtracting Characters
Subtract Logical Characters-$ LC
• Binary subtract A field characters from B field characters.
• A and B fields are the same length (Q code plus 1 ).
The subtract logical characters operation is the same as
the add logical characters operation except that the A field
data is subtracted from the B field data (Figure 3-15).
Figure 3-16 shows the significance of the CR settings. Al-
though the settings have a different significance, the CR
is set in the same manner as in the add logical characters
operation, except the binary overflow is not set on.
DM 5-080 contains the circuit description.
Compare Logical Characters-CLC
• Compare A field data to B field data.
• A and B fields are the same length (Q code plus 1 ).
During the compare logical characters operation, the CPU
compares the two fields by binary subtracting the A field
data from the B field data. The operation is the same as
a subtract logical operation except that the results are not
entered into storage (Figure 3-17). Instead, the A and B
fields remain unchanged by the operation and the ALU
3-10
Gate LSR Lo Normal To A
(ORR)
results are used merely to set the condition register (Figure
3-16).
DM 5-080 contains the circuit description.
Move Characters-MVC
• Move A field characters to B field location.
• A and B fields are the same length (Q code plus 1).
The move characters operation moves the A field data, one
byte at a time, into the B field location. The operation begins
with the low order position of each field and continues
until the high order position is reached.
The operation is the same as add logical characters, except
that the B field character is not loaded into the B register
(Figure 3-18). With the B register blank, the operation is
the same as adding the A field to zero.
Equal
Low
High
Aand B B field is B field is
fields are lower than
higher than
equal A field A field
-
Figure 3-16. Condition Register-Subtract or Compare Logical Character