## AS61860 Assembler

####

    ACKNOWLEDGMENT

         Thanks  to  Edgar  Puehringer  for  his contribution of the
    AS61860 cross assembler.

            Edgar Peuhringer
            edgar_pue at yahoo dot com

####

    61860 REGISTER SET

    The  SC61860  from  Sharp has 96 bytes of internal RAM which are
    used as registers and hardware stack.  The last  four  bytes  of
    the  internal  RAM  are  special  purpose registers (I/O, timers
    ...).  Here is a list of the 61860 registers:

            Reg     Address         Common use
            ---     -------         ----------
            i, j    0, 1            Length of block operations
            a, b    2, 3            Accumulator
            xl, xh  4, 5            Pointer for read operations
            yl, yh  6, 7            Pointer for write operations
            k - n   8 - 0x0b        General purpose (counters ...)
              -     0x0c - 0x5b     Stack
            ia      0x5c            Inport A
            ib      0x5d            Inport B
            fo      0x5e            Outport F
            cout    0x5f            Control port

         Other  parts  of  the  61860 are the 16 bit program counter
    (pc) and 16 bit data pointer (dp).  The ALU has a carry flag (c)
    and  a  zero  flag  (z).   There is an internal register d which
    can't be accessed with machine instructions.  It is filled  from
    i or j when executing block operations.

         In  addition  there  are  three 7 bit registers p, q, and r
    which are used to address the  internal  RAM  (r  is  the  stack
    pointer, p and q are used for block operations).

####

    PROCESSOR SPECIFIC DIRECTIVES

         The  AS61860 cross assembler has two (2) processor specific
    assembler directives which are used for the etc mnemonic  (which
    is a kind of a built-in switch/case statement):

            .default        A 16 bit address (same as .dw)
            .case           One byte followed by a 16 bit address

    Here is an example how this should be used (cut from a lst
    file):

       022B 7A 05 02 18         614         PTC     0x05,   CONT16
       022F 69                  615         DTC
       0230 4C 01 25            616         .CASE   0x4C,   SLOADI
       0233 4D 01 2F            617         .CASE   0x4D,   SMERGI
       0236 51 01 D2            618         .CASE   0x51,   QUITI
       0239 53 00 CD            619         .CASE   0x53,   LLISTI
       023C 56 01 D5            620         .CASE   0x56,   VERI
       023F 01 D1               621         .DEFAULT        CONT9

####

    61860 INSTRUCTION SET

         The following tables list all 61860 family mnemonics recog-
    nized by the AS61860 assembler.  Most of the mnemonics are  con-
    verted  into  8  bit  machine instructions with no argument or a
    one- or two-byte argument.  There are some exceptions for this:

            Mnemonic        Description
            --------        -----------
            jp              2 bit instruction, 6 bit argument
            cal             3 bit instruction, 13 bit argument
            ptc *)          1 byte instruction, 3 byte argument
            dtc *)          1 byte instruction, n bytes argument

            *) Not mentioned in the CPU specification from Sharp

    Load Immediate Register

            LII n           (n --> I)
            LIJ n
            LIA n
            LIB n
            LIP n
            LIQ n
            LIDP nm
            LIDL n          (DL is the low byte of DP)
            LP              (One byte version of LIP)
            RA              (Same as LIA 0, but only one byte)
            CLRA            (synonym for RA)

    Load Accumulator

            LDP             (P --> A)
            LDQ
            LDR
            LDM             ((P) --> A)
            LDD             ((DP) --> A)

    Store Accumulator

            STP             (A --> P)
            STQ
            STR
            STD             (A --> (DP))

    Move Data

            MVDM            ((P) --> (DP))
            MVMD            ((DP) --> (P))

    Exchange Data

            EXAB            (A <--> B)
            EXAM            (A <--> (P))

    Stack Operations

            PUSH            (R - 1 --> R, A --> (R))
            POP             ((R) --> A, R + 1 --> R)
            LEAVE           (0 --> (R))

    Block Move Data

            MVW             ((Q) --> (P), I+1 bytes)
            MVB             ((Q) --> (P), J+1 bytes)
            MVWD            ((DP) --> (P), I+1 bytes)
            MVBD            ((DP) --> (P), J+1 bytes)
            DATA            ((B,A) --> (P), I+1 bytes,
                            reads CPU ROM also)

    Block Exchange Data

            EXW             ((Q) <--> (P), I+1 bytes)
            EXB             ((Q) <--> (P), J+1 bytes)
            EXWD            ((DP) <--> (P), I+1 bytes)
            EXBD            ((DP) <--> (P), J+1 bytes)

    Increment and Decrement

            INCP            (P + 1 --> P)
            DECP
            INCI
            DECI
            INCJ
            DECJ
            INCA
            DECA
            INCB
            DECB
            INCK
            DECK
            INCL
            DECL
            IX              (X + 1 --> X, X --> DP)
            DX
            IY
            DY
            INCM *)
            DECM *)
            INCN *)
            DECN *)

            *) Not mentioned in the CPU specification from Sharp

    Increment/Decrement with Load/Store

            IXL             (Same as IX plus LDD)
            DXL
            IYS             (Same as IY plus STD)
            DYS

    Fill

            FILM            (A --> (P), I+1 bytes)
            FILD            (A --> (DP), I+1 bytes)

    Addition and Subtraction

            ADIA n          (A + n --> A)
            SBIA n
            ADIM n          ((P) + n --> (P))
            SBIM n
            ADM n           ((P) + A --> (P))
            SBM n
            ADCM n          ((P) + A --> (P), with carry)
            SBCM
            ADB             (like ADM, but 16 bit)
            SBB
            ADN             (like ADM, BCD addition, I+1 bytes)
            SBN
            ADW             ((P) + (Q) --> (P), BCD, I+1 bytes)
            SBW

    Shift Operations

            SRW             (shift I+1 bytes in (P) 4 bits right)
            SLW
            SR              (shift A 1 bit, with carry)
            SL
            SWP             (exchange low and high nibble of A)

    Boolean Operations

            ANIA n          (A & n --> A)
            ORIA n
            ANIM n          ((P) & n --> (P))
            ORIM n
            ANID n          ((DP) & n --> (DP))
            ORID n
            ANMA            ((P) & A --> (P))
            ORMA

    Compare

            CPIA n          (A - n --> c,z)
            CPIM n          ((P) - n --> c,z)
            CPMA            ((P) - A --> c,z)
            TSIA n          (A & n --> z)
            TSIM n          ((P) & n --> z)
            TSID n          ((DP) & n --> z)
            TSIP            ((P) & A --> z)

    CPU Control

            SC              (Set carry)
            RC
            NOPW            (no op)
            NOPT
            WAIT n          (wait 6+n cycles)
            WAITJ           (wait 5+4*I cycles)
            CUP             (synonym for WAITJ)

    Absolute Jumps

            JP nm
            JPZ nm          (on zero)
            JPNZ nm
            JPC nm
            JPNC nm
            PTC/DTC         (see 'Processor Specific Directives')
            PTJ/DTJ         (synonym for PTD/DTC)
            CPCAL/DTLRA     (synonym for PTC/DTC)
            CASE1/CASE2     (synonym for PTC/DTC)
            SETT/JST        (synonym for PTC/DTC)

    Relative Jumps

         These  operations  handle a jump relative to PC forward and
    back with  a  maximum  distance  of  255  byte.   The  assembler
    resolves 16 bit  addresses to 8 bit  relative  adresses.  If the
    target address is to far away, an error will be generated.  Note
    that relative jumps need 1 byte less than absolute jumps.

            JRP nm
            JRZP nm
            JRNZP nm        (jump relative non zero plus direction)
            JRCP nm
            JRNCP nm
            JRM nm
            JRZM nm
            JRNZM nm
            JRCM nm         (jump relative on carry minus direction)
            JRNCM nm
            LOOP nm         (decrements (R) and makes a JRNCM)

    Calls

            CALL nm
            CAL nm          (nm must be <= 0x1fff,
                            1 byte less code than CALL)
            RTN

    Input and output

            INA             (IA --> A)
            INB
            OUTA
            OUTB
            OUTF            (A --> FO)
            OUTC            (control port)
            TEST n          (timers, pins & n --> z)

    Unknown Commands

            READ            ((PC+1) -> A)
            READM           ((PC+1) -> (P))
            WRIT            (???)

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Last Updated: March 2021