Click above to get retro games delivered to your door ever month!

SYNTAX      [<LABEL>] CMPR <constant>

OPERANDS    0 . CM . 3

EXECUTION   (PC) + 1 . PC
            Compare AR(ARP) to AR0, placing the result in TC bit of status
            register ST1. Affects TC.
            Not affected by SXM; does not affect SXM.

DESCRIPTION The CMPR instruction performs the following comparisons
            dependent on the value of CM:
                  If CM = 00, test if AR(ARP) = AR0
                  If CM = 01, test if AR(ARP) < AR0
                  If CM = 10, test if AR(ARP) > AR0
                  If CM = 11, test if AR(ARP).NE.AR0
            If the result of the test is true, a one is loaded into the
            TC status bit; otherwise, TC is loaded with a zero. The
            auxiliary registers are treated as unsigned integers in the
            comparison.

WORDS       1

ENCODING    15 14 13 12 11 10  9  8  7  6  5  4  3  2  1  0
            +-----------------------------------------------+
            |1  1  0  0  1  1  1  0  0  1  0  1  0  0|  CM  |
            +-----------------------------------------------+

CYCLES

            +------------------------------------------------+
            |    Cycle Timings for a Single Instruction      |
            |------------------------------------------------|
            | PI/DI | PI/DE | PE/DI | PE/DE  | PR/DI | PR/DE |
            |-------+-------+-------+--------+-------+-------|
      '20   |   1   |   1   |  1+p  |  1+p   |   -   |   -   |
            |-------+-------+-------+--------+-------+-------|
     'C25   |   1   |   1   |  1+p  |  1+p   |   1   |   1   |
            |------------------------------------------------|
            |    Cycle Timings for a Repeat Instruction      |
            |------------------------------------------------|
      '20   |   n   |   n   |  n+p  |  n+p   |   -   |   -   |
            |-------+-------+-------+--------+-------+-------|
     'C25   |   n   |   n   |  n+p  |  n+p   |   n   |   n   |
            +------------------------------------------------+



EXAMPLE     CMPR  2     (ARP = 4)

                BEFORE        AFTER

            AR0  >FFFF   AR0  >FFFF
            AR4  >7FFF   AR4  >7FFF
             TC     >1    TC     >0