Logical OR
Organizational graphic tag to help group instructions

Mnemonic

 OR

Short and Long format of instruction



Description

The contents of the accumulator are ORed, bit by bit, with the contents of the addressed core-storage location. The result replaces the contents of the accumulator. ORing occurs only between corresponding bit positions in the accumulator and the core-storage word: bit 0 is ORed only with bit 0, bit 1 only with bit 1, and so on. The four possible ORing results are:


Bit Values  
From Core Storage Word From Accumulator Result in Accumulator
0 0 0
0 1 1
1 0 1
1 1 1

Contents of the addressed core-storage word are not changed as a result of the operation. An example of ORing is:

    0011 0101 1111 1010    Word in accumulator
OR  0101 0001 1010 0000    Word from core storage
    0111 0101 1111 1010    Result in accumulator

There are no addressing exceptions for the logical OR instruction; all forms of addressing that are described under "Effective-Address Generation" apply to the OR instruction.


Indicators: The carry and overflow indicators are not affected during the OR operation.

Programming Note: A common use of the OR instruction is in setting a particular bit to the on (1) condition.

For example:

    XXXX XXXX XXXX XXXX    Word in accumulator
OR  0000 0010 0000 0000    Mask in storage
    XXXX XX1X XXXX XXXX    Result in accumulator

Examples

Logical OR

Assembler Language Coding Hexadecimal Value Description of Instruction
Label   Operation   F T    
21 25
  
27 30
   32 33   35..40..
    OR         DISP E8XX OR contents of CSL at EA (I+DISP) with A
    OR     1   DISP E9XX OR contents of CSL at EA (XR1+DISP) with A
    OR     2   DISP EAXX OR contents of CSL at EA (XR2+DISP) with A
    OR     3   DISP EBXX OR contents of CSL at EA (XR3+DISP) with A
    OR   L     ADDR EC00XXXX OR contents of CSL at EA (Addr) with A
    OR   L 1   ADDR ED00XXXX OR contents of CSL at EA (Addr+XR1) with A
    OR   L 2   ADDR EE00XXXX OR contents of CSL at EA (Addr+XR2) with A
    OR   L 3   ADDR EF00XXXX OR contents of CSL at EA (Addr+XR3) with A
    OR   I     ADDR EC80XXXX OR contents of CSL at EA (V in CSL at Addr) with A
    OR   I 1   ADDR ED80XXXX OR contents of CSL at EA (V in CSL at "Addr+XR1") with A
    OR   I 2   ADDR EE80XXXX OR contents of CSL at EA (V in CSL at "Addr+XR2") with A
    OR   I 3   ADDR EF80XXXX OR contents of CSL at EA (V in CSL at "Addr+XR3") with A

But wait, there's MORE...

Valid HTML 4.01 Transitional