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SYNTAX      [<LABEL>] RTXM

OPERANDS    None

EXECUTION   (PC) + 1 . PC
            0 . TXM transmit mode status bit
            Affects TXM mode bit.

DESCRIPTION The RTXM instruction resets the TXM status bit which
            configures the serial port transmit section in a mode where
            it is controlled by an FSX (external framing pulse). The
            transmit operation is started when an external FSX pulse is
            applied. TXM may also be loaded by the LST1 and STXM
            instructions.

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  0  1  0  0  0  0  0 |
            +-----------------------------------------------+

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     RTXM              TXM is reset, configuring FSX as an input.