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SYNTAX      [<LABEL>] SBRK <constant>

OPERANDS    0 . constant . 255

EXECUTION   (PC) + 1 . PC
            AR(ARP) - 8-bit positive constant . AR(ARP)

DESCRIPTION The 8-bit immediate value is subtracted, right-justified, from
            the auxiliary register with the result replacing the auxiliary
            register contents. The subtraction takes place in the ARAU,
            with the immediate value treated as an 8-bit positive integer.

WORDS       1


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

CYCLES

            +------------------------------------------------+
            |     Cycle Timings for a Single Instruction     |
            |------------------------------------------------|
            | PI/DI | PI/DE | PE/DI | PE/DE  | PR/DI | PR/DE |
            |-------+-------+-------+--------+-------+-------|
      'C25  |   1   |   1   |  1+p  |  1+p   |   1   |   1   |
            |------------------------------------------------|
            |     Cycle Timings for a Repeat Instruction     |
            |------------------------------------------------|
      'C25  |                 not repeatable                 |
            +------------------------------------------------+



EXAMPLE     SBRK  >FF         (ARP = 7)

              BEFORE              AFTER

            AR7   >0          AR7 >FF01