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Comparison Instructions
Description
304
Area
Index Registers
Indirect addressing using
Index Registers
CMP(020) compares the unsigned binary data in S
result to Arithmetic Flags (the Greater Than, Greater Than or Equal, Equal,
Less Than or Equal, Less Than, and Not Equal Flags) in the Auxiliary Area.
Condition Flag Status
The following table shows the status of the Arithmetic Flags after execution of
CMP(020). (A status of "---" indicates that the Flag may be ON or OFF.)
CMP(020)
Result
>
S
> S
ON
ON
1
2
S
= S
OFF
ON
1
2
S
< S
OFF
OFF
1
2
Using CMP(020) Results in the Program
When CMP(020) is executed, the result is reflected in the Arithmetic Flags.
Control the desired output or right-hand instruction with a branch from the
same input condition that controls CMP(020), as shown in the following dia-
gram. In this case, the Equals Flag and output A will be turned ON when S
S
.
2
Correct Use of CMP(020)
Using CMP(020) Results in the Program
Do not program another instruction between CMP(020) and the instruction
controlled by the Arithmetic Flag because the other instruction might change
the status of the Arithmetic Flag. In this case, the results of instruction B might
change the results of CMP(020).
S
1
---
,IR0 to ,IR15
–2048 to +2047 ,IR0 to –2048 to +2047 ,IR15
DR0 to DR15, IR0 to IR15
,IR0+(++) to ,IR15+(++)
,–(– –)IR0 to, –(– –)IR15
Unsigned binary
comparison
Arithmetic Flags
(>, >=, =, <=, <, <>)
Flag status
> =
=
< =
OFF
OFF
ON
ON
OFF
ON
Arithmetic Flag
(Example: Equal Flag)
Section 3-7
S
2
and S
and outputs the
1
2
<
< >
OFF
ON
OFF
OFF
ON
ON
CMP
S1
S2
A
=
1
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