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Annotation of researchv10dc/dist/man/v3/manx/fptrap.3, revision 1.1

1.1     ! root        1: .pa 1
        !             2: .he '3/15/72''FPTRAP (III)'
        !             3: .ti 0
        !             4: NAME           fptrap  --  PDP-11/45 floating point simulator
        !             5: .sp
        !             6: .ti 0
        !             7: .nf
        !             8: SYNOPSIS       .globl fptrap
        !             9: .br
        !            10: sys ilgins; fptrap
        !            11: .fi
        !            12: .sp
        !            13: .ti 0
        !            14: DESCRIPTION    fptrap______
        !            15: is a package which picks up instructions which are illegal
        !            16: for the PDP-11/20, and if they correspond to 11/45 floating
        !            17: point instructions, simulates their operation.
        !            18: The following instructions are supported:
        !            19: 
        !            20:        cfcc
        !            21:        setf
        !            22:        seti
        !            23:        setd
        !            24:        setl
        !            25: .      ldfps   src             (not in assembler)
        !            26: .      stfps   dst             (not in assembler)
        !            27:        clrf    fdst
        !            28:        tstf    fsrc
        !            29:        absf    fdst
        !            30:        negf    fdst
        !            31:        mulf    fsrc,fr
        !            32:        modf    fsrc,fr
        !            33:        addf    fsrc,fr
        !            34:        movf    fsrc,fr (=ldf)
        !            35:        movf    fr,fdst (=stf)
        !            36:        subf    fsrc,fr
        !            37:        cmpf    fsrc,fr
        !            38:        divf    fsrc,fr
        !            39: .nf
        !            40: .      movei   fr,dst  (=stexp)  (not in assembler)
        !            41: .      movie   src,fr  (=ldexp)  (not in assembler)
        !            42:        movfi   fr,dst  (=stcfi)
        !            43:        movif   src,fr  (=ldcif)
        !            44:        movfo   fr,fdst (=stcxy)
        !            45:        movof   fsrc,fr (=ldcyx)
        !            46: .fi
        !            47: 
        !            48: Here src___ and dst___ stand for source and destination, fsrc____
        !            49: and fdst____ for floating source and destination, and fr__ for
        !            50: floating register.
        !            51: Notice that the names of several of the opcodes have changed.
        !            52: The only strange instruction
        !            53: is movf____, which turns into stf___ if its source
        !            54: operand is a floating register, and into ldf___ if not.
        !            55: .sp
        !            56: The simulator sets the floating condition codes
        !            57: on both ldf___ and stf___.
        !            58: The 11/45 hardware does not set
        !            59: the fcc on stf.
        !            60: 
        !            61: Short and long format for both floating point numbers
        !            62: and integers is supported.  Truncation mode is always in effect.
        !            63: Traps for overflow and other arithmetic errors are not supported.
        !            64: Illegal instructions or addresses cause a simulated trap
        !            65: so that a core image is produced.
        !            66: 
        !            67: The condition code bits are maintained correctly.
        !            68: 
        !            69: For floating-point source operands, immediate mode ((pc)+) is
        !            70: not supported, since the PDP-11/45
        !            71: handbook is not clear on what to do about it.
        !            72: 
        !            73: After an arithmetic error the result is generally
        !            74: meaningless.
        !            75: 
        !            76: The arithmetic is always done in double-precision, so exact
        !            77: but unrounded results are to be expected in single-precision
        !            78: mode.  Double precision results are probably less correct
        !            79: than the hardware will be.
        !            80: 
        !            81: The lower parts of the floating registers become meaningless
        !            82: during single-precision operations.
        !            83: .sp
        !            84: .ti 0
        !            85: FILES          kept in /usr/lib/liba.a
        !            86: .sp
        !            87: .ti 0
        !            88: SEE ALSO       PDP-11/45 handbook, ilgins(II)
        !            89: .sp
        !            90: .ti 0
        !            91: DIAGNOSTICS    trap, c-bit, v-bit
        !            92: .sp
        !            93: .ti 0
        !            94: BUGS           see above

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