I1620/i1620_sys.c - emulators/simh - Rivoreo Source Code Repositories

 /* i1620_sys.c: IBM 1620 simulator interface

    Copyright (c) 2002-2008, Robert M. Supnik

    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
    to deal in the Software without restriction, including without limitation
    the rights to use, copy, modify, merge, publish, distribute, sublicense,
    and/or sell copies of the Software, and to permit persons to whom the
    Software is furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in
    all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
    ROBERT M SUPNIK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
    IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
    CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

    Except as contained in this notice, the name of Robert M Supnik shall not be
    used in advertising or otherwise to promote the sale, use or other dealings
    in this Software without prior written authorization from Robert M Supnik.

    19-Mar-12    RMS     Fixed declaration of CCT (Mark Pizzolato)
 */

 #include "i1620_defs.h"
 #include <ctype.h>

 #define LINE_LNT        50

 extern DEVICE cpu_dev, tty_dev;
 extern DEVICE ptr_dev, ptp_dev;
 extern DEVICE lpt_dev;
 extern DEVICE cdr_dev, cdp_dev;
 extern DEVICE dp_dev;
 extern UNIT cpu_unit;
 extern REG cpu_reg[];
 extern uint8 M[MAXMEMSIZE];
 extern int8 cdr_to_alp[128], alp_to_cdp[256];

 /* SCP data structures and interface routines

    sim_name             simulator name string
    sim_PC               pointer to saved PC register descriptor
    sim_emax             maximum number of words for examine/deposit
    sim_devices          array of pointers to simulated devices
    sim_stop_messages    array of pointers to stop messages
    sim_load             binary loader
 */

 char sim_name[] = "IBM 1620";

 REG *sim_PC = &cpu_reg[0];

 int32 sim_emax = LINE_LNT;

 DEVICE *sim_devices[] = {
     &cpu_dev,
     &tty_dev,
     &ptr_dev,
     &ptp_dev,
     &cdr_dev,
     &cdp_dev,
     &lpt_dev,
     &dp_dev,
     NULL
     };

 const char *sim_stop_messages[] = {
     "Unknown error",
     "HALT instruction",
     "Breakpoint",
     "Invalid instruction",
     "Invalid digit",
     "Invalid character",
     "Invalid indicator",
     "Invalid digit in P address",
     "Invalid P address",
     "P address exceeds indirect address limit",
     "Invalid digit in Q address",
     "Invalid Q address",
     "Q address exceeds indirect address limit",
     "Invalid IO device",
     "Invalid return register",
     "Invalid IO function",
     "Instruction address must be even",
     "Invalid select code",
     "Index instruction with no band selected",
     "P address must be odd",
     "DCF address must be even",
     "Invalid disk drive",
     "Invalid disk sector address",
     "Invalid disk sector count",
     "Invalid disk buffer address",
     "Disk address compare error",
     "Disk write check error",
     "Disk cylinder overflow error",
     "Disk wrong length record error",
     "Invalid CCT",
     "Field exceeds memory",
     "Record exceeds memory",
     "No card in reader",
     "Overflow check",
     "Exponent check",
     "Write address function disabled",
     "Floating point mantissa too long",
     "Floating point mantissa lengths unequal",
     "Floating point exponent flag missing",
     "Floating point divide by zero"
     };

 /* Binary loader -- load carriage control tape

    A carriage control tape consists of entries of the form

         (repeat count) column number,column number,column number,...

    The CCT entries are stored in cct[0:lnt-1], cctlnt contains the
    number of entries
 */

 t_stat sim_load (FILE *fileref, char *cptr, char *fnam, int flag)
 {
 uint32 col, mask, cctbuf[CCT_LNT];
 int32 ptr, rpt;
 t_stat r;
 extern int32 cct_lnt, cct_ptr;
 extern uint32 cct[CCT_LNT];
 char cbuf[CBUFSIZE], gbuf[CBUFSIZE];

 if ((*cptr != 0) || (flag != 0))
     return SCPE_ARG;
 ptr = 0;
 for ( ; (cptr = fgets (cbuf, CBUFSIZE, fileref)) != NULL; ) { /* until eof */
     mask = 0;
     if (*cptr == '(') {                                 /* repeat count? */
         cptr = get_glyph (cptr + 1, gbuf, ')');         /* get 1st field */
         rpt = get_uint (gbuf, 10, CCT_LNT, &r);         /* repeat count */
         if (r != SCPE_OK)
             return SCPE_FMT;
         }
     else rpt = 1;
     while (*cptr != 0) {                                /* get col no's */
         cptr = get_glyph (cptr, gbuf, ',');             /* get next field */
         col = get_uint (gbuf, 10, 12, &r);              /* column number */
         if (r != SCPE_OK)
             return SCPE_FMT;
         mask = mask | (1 << col);                       /* set bit */
         }
     for ( ; rpt > 0; rpt--) {                           /* store vals */
         if (ptr >= CCT_LNT)
             return SCPE_FMT;
         cctbuf[ptr++] = mask;
         }
     }
 if (ptr == 0)
     return SCPE_FMT;
 cct_lnt = ptr;
 cct_ptr = 0;
 for (rpt = 0; rpt < cct_lnt; rpt++)
     cct[rpt] = cctbuf[rpt];
 return SCPE_OK;
 }

 /* Symbol table */

 struct opc {
     char                *str;                           /* mnemonic */
     uint32              opv;                            /* opcode & flags */
     uint32              qv;                             /* q field */
     };

 #define I_V_FL          16                              /* flags */
 #define I_M_QX          0x01                            /* Q indexable */
 #define I_M_QM          0x02                            /* Q immediate */
 #define I_M_QNP         0x00                            /* Q no print */
 #define I_M_QCP         0x04                            /* Q cond print */
 #define I_M_QP          0x08                            /* Q print */
 #define I_M_PCP         0x00                            /* P cond print */
 #define I_M_PP          0x10                            /* P print */
 #define I_GETQF(x)      (((x) >> I_V_FL) & 0x03)
 #define I_GETQP(x)      (((x) >> I_V_FL) & 0x0C)
 #define I_GETPP(x)      (((x) >> I_V_FL) & 0x10)

 #define I_2             ((I_M_PP | I_M_QP | I_M_QX) << I_V_FL)
 #define I_2M            ((I_M_PP | I_M_QP | I_M_QM) << I_V_FL)
 #define I_2X            ((I_M_PP | I_M_QP | I_M_QX | I_M_QM) << I_V_FL)
 #define I_2S            ((I_M_PP | I_M_QP) << I_V_FL)
 #define I_1             ((I_M_PP | I_M_QCP) << I_V_FL)
 #define I_1E            ((I_M_PP | I_M_QNP) << I_V_FL)
 #define I_0             ((I_M_PCP | I_M_QCP) << I_V_FL)
 #define I_0E            ((I_M_PCP | I_M_QNP) << I_V_FL)

 struct opc opcode[] = {
     { "RNTY", 36+I_1E,  100 }, { "RATY", 37+I_1E,  100 },
     { "WNTY", 38+I_1E,  100 }, { "WATY", 39+I_1E,  100 },
     { "DNTY", 35+I_1E,  100 }, { "SPTY", 34+I_0E,  101 },
     { "RCTY", 34+I_0E,  102 }, { "BKTY", 34+I_0E,  103 },
     { "IXTY", 34+I_0E,  104 }, { "TBTY", 34+I_0E,  108 },
     { "RNPT", 36+I_1E,  300 }, { "RAPT", 37+I_1E,  300 },
     { "WNPT", 38+I_1E,  200 }, { "WAPT", 39+I_1E,  200 },
     { "DNPT", 35+I_1E,  200 },
     { "RNCD", 36+I_1E,  500 }, { "RACD", 37+I_1E,  500 },
     { "WNCD", 38+I_1E,  400 }, { "WACD", 39+I_1E,  400 },
     { "DNCD", 35+I_1E,  400 },
     { "PRN",  38+I_1E,  900 }, { "PRNS", 38+I_1E,  901 },
     { "PRA",  39+I_1E,  900 }, { "PRAS", 39+I_1E,  901 },
     { "PRD",  35+I_1E,  900 }, { "PRDS", 35+I_1E,  901 },
     { "SK",   34+I_1E,  701 },
     { "RDGN", 36+I_1E,  700 }, { "CDGN", 36+I_1E,  701 },
     { "RDN",  36+I_1E,  702 }, { "CDN",  36+I_1E,  703 },
     { "RTGN", 36+I_1E,  704 }, { "CTGN", 36+I_1E,  705 },
     { "RTN",  36+I_1E,  706 }, { "CTN",  36+I_1E,  707 },
     { "WDGN", 38+I_1E,  700 }, { "WDN",  38+I_1E,  702 },
     { "WTGN", 38+I_1E,  704 }, { "WTN",  38+I_1E,  706 },
     { "RBPT", 37+I_1E, 3300 }, { "WBPT", 39+I_1E, 3200 },
     { "BC1",  46+I_1E,  100 }, { "BNC1", 47+I_1E,  100 },
     { "BC2",  46+I_1E,  200 }, { "BNC2", 47+I_1E,  200 },
     { "BC3",  46+I_1E,  300 }, { "BNC3", 47+I_1E,  300 },
     { "BC4",  46+I_1E,  400 }, { "BNC4", 47+I_1E,  400 },
     { "BLC",  46+I_1E,  900 }, { "BNLC", 47+I_1E,  900 },
     { "BH",   46+I_1E, 1100 }, { "BNH",  47+I_1E, 1100 },
     { "BP",   46+I_1E, 1100 }, { "BNP",  47+I_1E, 1100 },
     { "BE",   46+I_1E, 1200 }, { "BNE",  47+I_1E, 1200 },
     { "BZ",   46+I_1E, 1200 }, { "BNZ",  47+I_1E, 1200 },
     { "BNL",  46+I_1E, 1300 }, { "BL",   47+I_1E, 1300 },
     { "BNN",  46+I_1E, 1300 }, { "BN",   47+I_1E, 1300 },
     { "BV",   46+I_1E, 1400 }, { "BNV",  47+I_1E, 1400 },
     { "BXV",  46+I_1E, 1500 }, { "BNXV", 47+I_1E, 1500 },
     { "BA",   46+I_1E, 1900 }, { "BNA",  47+I_1E, 1900 },
     { "BNBS", 46+I_1E, 3000 }, { "BEBS", 47+I_1E, 3000 },
     { "BBAS", 46+I_1E, 3100 }, { "BANS", 47+I_1E, 3100 },
     { "BBBS", 46+I_1E, 3200 }, { "BBNS", 47+I_1E, 3200 },
     { "BCH9", 46+I_1E, 3300 },
     { "BCOV", 46+I_1E, 3400 },
     { "BSNX", 60+I_1E,    0 }, { "BSBA", 60+I_1E,    1 },
     { "BSBB", 60+I_1E,    2 },
     { "BSNI", 60+I_1E,    8 }, { "BSIA", 60+I_1E,    9 },

     { "FADD",  1+I_2,  0 }, { "FSUB",  2+I_2,  0 },
     { "FMUL",  3+I_2,  0 }, { "FSL",   5+I_2,  0 },
     { "TFL",   6+I_2,  0 }, { "BTFL",  7+I_2,  0 },
     { "FSR",   8+I_2,  0 }, { "FDIV",  9+I_2,  0 },
     { "BTAM", 10+I_2M, 0 }, { "AM",   11+I_2M, 0 },
     { "SM",   12+I_2M, 0 }, { "MM",   13+I_2M, 0 },
     { "CM",   14+I_2M, 0 }, { "TDM",  15+I_2S, 0 },
     { "TFM",  16+I_2M, 0 }, { "BTM",  17+I_2M, 0 },
     { "LDM",  18+I_2M, 0 }, { "DM",   19+I_2M, 0 },
     { "BTA",  20+I_2,  0 }, { "A",    21+I_2,  0 },
     { "S",    22+I_2,  0 }, { "M",    23+I_2,  0 },
     { "C",    24+I_2,  0 }, { "TD",   25+I_2,  0 },
     { "TF",   26+I_2,  0 }, { "BT",   27+I_2,  0 },
     { "LD",   28+I_2,  0 }, { "D",    29+I_2,  0 },
     { "TRNM", 30+I_2,  0 }, { "TR",   31+I_2,  0 },
     { "SF",   32+I_1,  0 }, { "CF",   33+I_1,  0 },
     { "K",    34+I_2S, 0 }, { "DN",   35+I_2S, 0 },
     { "RN",   36+I_2S, 0 }, { "RA",   37+I_2S, 0 },
     { "WN",   38+I_2S, 0 }, { "WA",   39+I_2S, 0 },
     { "NOP",  41+I_0,  0 }, { "BB",   42+I_0,  0 },
     { "BD",   43+I_2,  0 }, { "BNF",  44+I_2,  0 },
     { "BNR",  45+I_2,  0 }, { "BI",   46+I_2S, 0 },
     { "BNI",  47+I_2S, 0 }, { "H",    48+I_0,  0 },
     { "B",    49+I_1,  0 }, { "BNG",  55+I_2,  0 },
     { "BS",   60+I_2S, 0 }, { "BX",   61+I_2,  0 },
     { "BXM",  62+I_2X, 0 }, { "BCX",  63+I_2,  0 },
     { "BCXM", 64+I_2X, 0 }, { "BLX",  65+I_2,  0 },
     { "BLXM", 66+I_2X, 0 }, { "BSX",  67+I_2,  0 },
     { "MA",   70+I_2,  0 }, { "MF",   71+I_2,  0 },
     { "TNS",  72+I_2,  0 }, { "TNF",  73+I_2,  0 },
     { "BBT",  90+I_2,  0 }, { "BMK",  91+I_2,  0 },
     { "ORF",  92+I_2,  0 }, { "ANDF", 93+I_2,  0 },
     { "CPFL", 94+I_2,  0 }, { "EORF", 95+I_2,  0 },
     { "OTD",  96+I_2,  0 }, { "DTO",  97+I_2,  0 },
     { NULL,   0, 0 }
     };

 /* Print an address from five characters */

 /* Use scp.c provided fprintf function */
 #define fprintf Fprintf
 #define fputs(_s,f) Fprintf(f,"%s",_s)
 #define fputc(_c,f) Fprintf(f,"%c",_c)

 void fprint_addr (FILE *of, int32 spc, t_value *dig, t_bool flg)
 {
 int32 i, idx;

 fputc (spc, of);                                        /* spacer */
 if (dig[ADDR_LEN - 1] & FLAG) {                         /* signed? */
     fputc ('-', of);                                    /* print minus */
     dig[ADDR_LEN - 1] = dig[ADDR_LEN - 1] & ~FLAG;
     }
 for (i = 0; i < ADDR_LEN; i++)                          /* print digits */
     fprintf (of, "%X", dig[i] & DIGIT);
 if ((cpu_unit.flags & IF_IDX) && flg) {                 /* indexing? */
     for (i = idx = 0; i < ADDR_LEN - 2; i++) {          /* get index reg */
         if (dig[ADDR_LEN - 2 - i] & FLAG)
             idx = idx | (1 << i);
         dig[ADDR_LEN - 2 - i] = dig[ADDR_LEN - 2 - i] & ~FLAG;
         }
     if (idx)                                            /* print */
         fprintf (of, "(%d)", idx);
     }
 return;
 }

 /* Symbolic decode

    Inputs:
         *of     =       output stream
         addr    =       current address
         *val    =       values to decode
         *uptr   =       pointer to unit
         sw      =       switches
    Outputs:
         return  =       if >= 0, error code
                         if < 0, number of extra words retired
 */

 #define FMTASC(x) ((x) < 040)? "<%03o>": "%c", (x)

 t_stat fprint_sym (FILE *of, t_addr addr, t_value *val,
     UNIT *uptr, int32 sw)
 {
 int32 pmp, qmp, i, c, d, any;
 uint32 op, qv, opfl;

 if (uptr == NULL)
     uptr = &cpu_unit;
 if (sw & SWMASK ('C')) {                                /* character? */
     if (uptr->flags & UNIT_BCD) {
         if (addr & 1)                                   /* must be even */
             return SCPE_ARG;
         c = ((val[0] & DIGIT) << 4) | (val[1] & DIGIT);
         if (alp_to_cdp[c] > 0)
             fprintf (of, "%c", alp_to_cdp[c]);
         else fprintf (of, "<%02x>", c);
         return -1;
         }
     else fprintf (of, FMTASC (val[0] & 0177));
     return SCPE_OK;
     }
 if ((uptr->flags & UNIT_BCD) == 0)                      /* CPU or disk? */
     return SCPE_ARG;
 if (sw & SWMASK ('D')) {                                /* dump? */
     for (i = d = 0; i < LINE_LNT; i++)
         d = d | val[i];
     if (d & FLAG) {                                     /* any flags? */
         for (i = 0; i < LINE_LNT; i++)                  /* print flags */
             fprintf (of, (val[i] & FLAG)? "_": " ");
         fprintf (of, "\n\t");
         }
     for (i = 0; i < LINE_LNT; i++)                      /* print digits */
         fprintf (of, "%X", val[i] & DIGIT) ;
     return -(i - 1);
     }
 if (sw & SWMASK ('S')) {                                /* string? */
     if (addr & 1)                                       /* must be even */
         return SCPE_ARG;
     for (i = 0; i < LINE_LNT; i = i + 2) {
         c = ((val[i] & DIGIT) << 4) | (val[i + 1] & DIGIT);
         if (alp_to_cdp[c] < 0)
             break;
         fprintf (of, "%c", alp_to_cdp[c]);
         }
     if (i == 0) {
         fprintf (of, "<%02X>", c);
         return -1;
         }
     return -(i - 1);
     }
 if ((sw & SWMASK ('M')) == 0)
     return SCPE_ARG;

 if (addr & 1)                                           /* must be even */
     return SCPE_ARG;
 op = ((val[0] & DIGIT) * 10) + (val[1] & DIGIT);        /* get opcode */
 for (i = qv = pmp = qmp = 0; i < ADDR_LEN; i++) {       /* test addr */
     if (val[I_P + i])
         pmp = 1;
     if (val[I_Q + i])
         qmp = 1;
     qv = (qv * 10) + (val[I_Q + i] & DIGIT);
     }
 if ((val[0] | val[1]) & FLAG)                           /* flags force */
     pmp = qmp = 1;
 for (i = 0; opcode[i].str != NULL; i++) {               /* find opcode */
     opfl = opcode[i].opv & 0xFF0000;
     if ((op == (opcode[i].opv & 0xFF)) &&
         ((qv == opcode[i].qv) ||
         ((opfl != I_1E) && (opfl != I_0E))))
         break;
     }
 if (opcode[i].str == NULL)
     return SCPE_ARG;
 if (I_GETQP (opfl) == I_M_QNP)                          /* Q no print? */
     qmp = 0;

 fprintf (of, "%s", opcode[i].str);                      /* print opcode */
 if (I_GETPP (opfl) == I_M_PP)                           /* P required? */
     fprint_addr (of, ' ', &val[I_P], I_M_QX);
 else if ((I_GETPP (opfl) == I_M_PCP) && (pmp || qmp))   /* P opt & needed? */
     fprint_addr (of, ' ', &val[I_P], 0);
 if (I_GETQP (opfl) == I_M_QP) {                         /* Q required? */
     fprint_addr (of, ',', &val[I_Q], I_GETQF (opfl));
     if (I_GETQF (opfl) & I_M_QM)                        /* immediate? */
         val[I_Q] = val[I_Q] & ~FLAG;                    /* clr hi Q flag */
     }
 else if ((I_GETQP (opfl) == I_M_QCP) && (pmp || qmp))   /* Q opt & needed? */
     fprint_addr (of, ',', &val[I_Q], 0);
 for (i = any = 0; i < INST_LEN; i++) {                  /* print rem flags */
     if (val[i] & FLAG) {
         if (!any)
             fputc (',', of);
         any = 1;
         fprintf (of, "%d", i);
         }
     }
 return -(INST_LEN - 1);
 }

 /* parse_addr - get sign + address + index */

 t_stat parse_addr (char *cptr, t_value *val, int32 flg)
 {
 int32 i, sign = 0, addr, index;
 static int32 idx_tst[ADDR_LEN] = { 0, 4, 2, 1, 0 };
 char *tptr;

 if (*cptr == '+')                                       /* +? skip */
     cptr++;
 else if (*cptr == '-') {                                /* -? skip, flag */
     sign = 1;
     cptr++;
     }
 errno = 0;                                              /* get address */
 addr = strtoul (cptr, &tptr, 16);
 if (errno || (cptr == tptr) || (addr > 0xFFFFF))        /* err or too big? */
     return SCPE_ARG;
 if ((cpu_unit.flags & IF_IDX) && (flg & I_M_QX) &&      /* index allowed? */
     (*tptr == '(')) {                                   /* index specified */
         errno = 0;
         index = strtoul (cptr = tptr + 1, &tptr, 10);   /* get index */
         if (errno || (cptr == tptr) || (index > 7))     /* err or too big? */
             return SCPE_ARG;
         if (*tptr++ != ')')
             return SCPE_ARG;
         }
 else index = 0;
 if (*tptr != 0)                                         /* all done? */
     return SCPE_ARG;
 for (i = ADDR_LEN - 1; i >= 0; i--) {                   /* cvt addr to dig */
     val[i] = (addr & 0xF) | ((index & idx_tst[i])? FLAG: 0);
     addr = addr >> 4;
     }
 if (sign)                                               /* set sign */
     val[ADDR_LEN - 1] = val[ADDR_LEN - 1] | FLAG;
 if (flg & I_M_QM)                                       /* set immediate */
     val[0] = val[0] | FLAG;
 return SCPE_OK;
 }

 /* Symbolic input

    Inputs:
         *cptr   =       pointer to input string
         addr    =       current PC
         *uptr   =       pointer to unit
         *val    =       pointer to output values
         sw      =       switches
    Outputs:
         status  =       > 0   error code
                         <= 0  -number of extra words
 */

 t_stat parse_sym (char *cptr, t_addr addr, UNIT *uptr, t_value *val, int32 sw)
 {
 int32 i, qv, opfl, last;
 char la, *fptr, gbuf[CBUFSIZE];
 int8 t;

 while (isspace (*cptr))                                 /* absorb spaces */
     cptr++;
 if ((sw & SWMASK ('C')) || ((*cptr == '\'') && cptr++)) { /* character? */
     if ((t = *cptr & 0x7F) == 0)                        /* get char */
         return SCPE_ARG;
     if (uptr->flags & UNIT_BCD) {                       /* BCD? */
         if (addr & 1)
             return SCPE_ARG;
         t = cdr_to_alp[t];                              /* convert */
         if (t < 0)                                      /* invalid? */
             return SCPE_ARG;
         val[0] = (t >> 4) & DIGIT;                      /* store */
         val[1] = t & DIGIT;
         return -1;
         }
     else val[0] = t;                                    /* store ASCII */
     return SCPE_OK;
     }

 if ((uptr->flags & UNIT_BCD) == 0)                      /* CPU or disk? */
     return SCPE_ARG;
 if ((sw & SWMASK ('S')) || ((*cptr == '"') && cptr++)) { /* string? */
     if (addr & 1)                                       /* must be even */
         return SCPE_ARG;
     for (i = 0; (i < sim_emax) && (*cptr != 0); i = i + 2) {
         t = *cptr++ & 0x7F;                             /* get character */
         t = cdr_to_alp[t];                              /* convert */
         if (t < 0)                                      /* invalid? */
             return SCPE_ARG;
         val[i] = (t >> 4) & DIGIT;                      /* store */
         val[i + 1] = t & DIGIT;
         }
     if (i == 0)                                         /* final check */
         return SCPE_ARG;
     return -(i - 1);
     }

 if (addr & 1)                                           /* even addr? */
     return SCPE_ARG;
 cptr = get_glyph (cptr, gbuf, 0);                       /* get opcode */
 for (i = 0; opcode[i].str != NULL; i++) {               /* look it up */
     if (strcmp (gbuf, opcode[i].str) == 0)
         break;
     }
 if (opcode[i].str == NULL)                              /* successful? */
     return SCPE_ARG;
 opfl = opcode[i].opv & 0xFF0000;                        /* get flags */
 val[0] = (opcode[i].opv & 0xFF) / 10;                   /* store opcode */
 val[1] = (opcode[i].opv & 0xFF) % 10;
 qv = opcode[i].qv;
 for (i = ADDR_LEN - 1; i >= 0; i--) {                   /* set P,Q fields */
     val[I_P + i] = 0;
     val[I_Q + i] = qv % 10;
     qv = qv /10;
     }

 cptr = get_glyph (cptr, gbuf, ',');                     /* get P field */
 if (gbuf[0]) {                                          /* any? */
     if (parse_addr (gbuf, &val[I_P], (I_GETPP (opfl)? I_M_QX: 0)))
         return SCPE_ARG;
     }
 else if (I_GETPP (opfl) == I_M_PP)
     return SCPE_ARG;

 if (I_GETQP (opfl) != I_M_QNP) {                        /* Q field allowed? */
     cptr = get_glyph (cptr, gbuf, ',');                 /* get Q field */
     if (gbuf[0]) {                                      /* any? */
         if (parse_addr (gbuf, &val[I_Q], I_GETQF (opfl)))
             return SCPE_ARG;
         }
     else if (I_GETQP (opfl) == I_M_QP)
         return SCPE_ARG;
     }

 cptr = get_glyph (cptr, fptr = gbuf, ' ');              /* get flag field */
 last = -1;                                              /* none yet */
 while ((t = *fptr++)) {                                 /* loop through */
     if ((t < '0') || (t > '9'))                         /* must be digit */
         return SCPE_ARG;
     t = t - '0';                                        /* convert */
     if (t == 1) {                                       /* ambiguous? */
         la = *fptr++;                                   /* get next */
         if (la == '0')                                  /* 10? */
             t = 10;
         else if ((la == '1') && (*fptr == 0))           /* 11 & end field? */
             t = 11;
         else --fptr;                                    /* dont lookahead */
         }
     if (t <= last)                                      /* in order? */
         return SCPE_ARG;
     val[t] = val[t] | FLAG;                             /* set flag */
     last = t;                                           /* continue */
     }

 if (*cptr != 0)
     return SCPE_ARG;
 return -(INST_LEN - 1);
 }
	/* i1620_sys.c: IBM 1620 simulator interface

	Copyright (c) 2002-2008, Robert M. Supnik

	Permission is hereby granted, free of charge, to any person obtaining a
	copy of this software and associated documentation files (the "Software"),
	to deal in the Software without restriction, including without limitation
	the rights to use, copy, modify, merge, publish, distribute, sublicense,
	and/or sell copies of the Software, and to permit persons to whom the
	Software is furnished to do so, subject to the following conditions:

	The above copyright notice and this permission notice shall be included in
	all copies or substantial portions of the Software.

	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	ROBERT M SUPNIK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
	IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
	CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

	Except as contained in this notice, the name of Robert M Supnik shall not be
	used in advertising or otherwise to promote the sale, use or other dealings
	in this Software without prior written authorization from Robert M Supnik.

	19-Mar-12 RMS Fixed declaration of CCT (Mark Pizzolato)
	*/

	#include "i1620_defs.h"
	#include <ctype.h>

	#define LINE_LNT 50

	extern DEVICE cpu_dev, tty_dev;
	extern DEVICE ptr_dev, ptp_dev;
	extern DEVICE lpt_dev;
	extern DEVICE cdr_dev, cdp_dev;
	extern DEVICE dp_dev;
	extern UNIT cpu_unit;
	extern REG cpu_reg[];
	extern uint8 M[MAXMEMSIZE];
	extern int8 cdr_to_alp[128], alp_to_cdp[256];

	/* SCP data structures and interface routines

	sim_name simulator name string
	sim_PC pointer to saved PC register descriptor
	sim_emax maximum number of words for examine/deposit
	sim_devices array of pointers to simulated devices
	sim_stop_messages array of pointers to stop messages
	sim_load binary loader
	*/

	char sim_name[] = "IBM 1620";

	REG *sim_PC = &cpu_reg[0];

	int32 sim_emax = LINE_LNT;

	DEVICE *sim_devices[] = {
	&cpu_dev,
	&tty_dev,
	&ptr_dev,
	&ptp_dev,
	&cdr_dev,
	&cdp_dev,
	&lpt_dev,
	&dp_dev,
	NULL
	};

	const char *sim_stop_messages[] = {
	"Unknown error",
	"HALT instruction",
	"Breakpoint",
	"Invalid instruction",
	"Invalid digit",
	"Invalid character",
	"Invalid indicator",
	"Invalid digit in P address",
	"Invalid P address",
	"P address exceeds indirect address limit",
	"Invalid digit in Q address",
	"Invalid Q address",
	"Q address exceeds indirect address limit",
	"Invalid IO device",
	"Invalid return register",
	"Invalid IO function",
	"Instruction address must be even",
	"Invalid select code",
	"Index instruction with no band selected",
	"P address must be odd",
	"DCF address must be even",
	"Invalid disk drive",
	"Invalid disk sector address",
	"Invalid disk sector count",
	"Invalid disk buffer address",
	"Disk address compare error",
	"Disk write check error",
	"Disk cylinder overflow error",
	"Disk wrong length record error",
	"Invalid CCT",
	"Field exceeds memory",
	"Record exceeds memory",
	"No card in reader",
	"Overflow check",
	"Exponent check",
	"Write address function disabled",
	"Floating point mantissa too long",
	"Floating point mantissa lengths unequal",
	"Floating point exponent flag missing",
	"Floating point divide by zero"
	};

	/* Binary loader -- load carriage control tape

	A carriage control tape consists of entries of the form

	(repeat count) column number,column number,column number,...

	The CCT entries are stored in cct[0:lnt-1], cctlnt contains the
	number of entries
	*/

	t_stat sim_load (FILE fileref, char cptr, char *fnam, int flag)
	{
	uint32 col, mask, cctbuf[CCT_LNT];
	int32 ptr, rpt;
	t_stat r;
	extern int32 cct_lnt, cct_ptr;
	extern uint32 cct[CCT_LNT];
	char cbuf[CBUFSIZE], gbuf[CBUFSIZE];

	if ((*cptr != 0) \|\| (flag != 0))
	return SCPE_ARG;
	ptr = 0;
	for ( ; (cptr = fgets (cbuf, CBUFSIZE, fileref)) != NULL; ) { /* until eof */
	mask = 0;
	if (cptr == '(') { / repeat count? */
	cptr = get_glyph (cptr + 1, gbuf, ')'); /* get 1st field */
	rpt = get_uint (gbuf, 10, CCT_LNT, &r); /* repeat count */
	if (r != SCPE_OK)
	return SCPE_FMT;
	}
	else rpt = 1;
	while (cptr != 0) { / get col no's */
	cptr = get_glyph (cptr, gbuf, ','); /* get next field */
	col = get_uint (gbuf, 10, 12, &r); /* column number */
	if (r != SCPE_OK)
	return SCPE_FMT;
	mask = mask \| (1 << col); /* set bit */
	}
	for ( ; rpt > 0; rpt--) { /* store vals */
	if (ptr >= CCT_LNT)
	return SCPE_FMT;
	cctbuf[ptr++] = mask;
	}
	}
	if (ptr == 0)
	return SCPE_FMT;
	cct_lnt = ptr;
	cct_ptr = 0;
	for (rpt = 0; rpt < cct_lnt; rpt++)
	cct[rpt] = cctbuf[rpt];
	return SCPE_OK;
	}

	/* Symbol table */

	struct opc {
	char str; / mnemonic */
	uint32 opv; /* opcode & flags */
	uint32 qv; /* q field */
	};

	#define I_V_FL 16 /* flags */
	#define I_M_QX 0x01 /* Q indexable */
	#define I_M_QM 0x02 /* Q immediate */
	#define I_M_QNP 0x00 /* Q no print */
	#define I_M_QCP 0x04 /* Q cond print */
	#define I_M_QP 0x08 /* Q print */
	#define I_M_PCP 0x00 /* P cond print */
	#define I_M_PP 0x10 /* P print */
	#define I_GETQF(x) (((x) >> I_V_FL) & 0x03)
	#define I_GETQP(x) (((x) >> I_V_FL) & 0x0C)
	#define I_GETPP(x) (((x) >> I_V_FL) & 0x10)

	#define I_2 ((I_M_PP \| I_M_QP \| I_M_QX) << I_V_FL)
	#define I_2M ((I_M_PP \| I_M_QP \| I_M_QM) << I_V_FL)
	#define I_2X ((I_M_PP \| I_M_QP \| I_M_QX \| I_M_QM) << I_V_FL)
	#define I_2S ((I_M_PP \| I_M_QP) << I_V_FL)
	#define I_1 ((I_M_PP \| I_M_QCP) << I_V_FL)
	#define I_1E ((I_M_PP \| I_M_QNP) << I_V_FL)
	#define I_0 ((I_M_PCP \| I_M_QCP) << I_V_FL)
	#define I_0E ((I_M_PCP \| I_M_QNP) << I_V_FL)

	struct opc opcode[] = {
	{ "RNTY", 36+I_1E, 100 }, { "RATY", 37+I_1E, 100 },
	{ "WNTY", 38+I_1E, 100 }, { "WATY", 39+I_1E, 100 },
	{ "DNTY", 35+I_1E, 100 }, { "SPTY", 34+I_0E, 101 },
	{ "RCTY", 34+I_0E, 102 }, { "BKTY", 34+I_0E, 103 },
	{ "IXTY", 34+I_0E, 104 }, { "TBTY", 34+I_0E, 108 },
	{ "RNPT", 36+I_1E, 300 }, { "RAPT", 37+I_1E, 300 },
	{ "WNPT", 38+I_1E, 200 }, { "WAPT", 39+I_1E, 200 },
	{ "DNPT", 35+I_1E, 200 },
	{ "RNCD", 36+I_1E, 500 }, { "RACD", 37+I_1E, 500 },
	{ "WNCD", 38+I_1E, 400 }, { "WACD", 39+I_1E, 400 },
	{ "DNCD", 35+I_1E, 400 },
	{ "PRN", 38+I_1E, 900 }, { "PRNS", 38+I_1E, 901 },
	{ "PRA", 39+I_1E, 900 }, { "PRAS", 39+I_1E, 901 },
	{ "PRD", 35+I_1E, 900 }, { "PRDS", 35+I_1E, 901 },
	{ "SK", 34+I_1E, 701 },
	{ "RDGN", 36+I_1E, 700 }, { "CDGN", 36+I_1E, 701 },
	{ "RDN", 36+I_1E, 702 }, { "CDN", 36+I_1E, 703 },
	{ "RTGN", 36+I_1E, 704 }, { "CTGN", 36+I_1E, 705 },
	{ "RTN", 36+I_1E, 706 }, { "CTN", 36+I_1E, 707 },
	{ "WDGN", 38+I_1E, 700 }, { "WDN", 38+I_1E, 702 },
	{ "WTGN", 38+I_1E, 704 }, { "WTN", 38+I_1E, 706 },
	{ "RBPT", 37+I_1E, 3300 }, { "WBPT", 39+I_1E, 3200 },
	{ "BC1", 46+I_1E, 100 }, { "BNC1", 47+I_1E, 100 },
	{ "BC2", 46+I_1E, 200 }, { "BNC2", 47+I_1E, 200 },
	{ "BC3", 46+I_1E, 300 }, { "BNC3", 47+I_1E, 300 },
	{ "BC4", 46+I_1E, 400 }, { "BNC4", 47+I_1E, 400 },
	{ "BLC", 46+I_1E, 900 }, { "BNLC", 47+I_1E, 900 },
	{ "BH", 46+I_1E, 1100 }, { "BNH", 47+I_1E, 1100 },
	{ "BP", 46+I_1E, 1100 }, { "BNP", 47+I_1E, 1100 },
	{ "BE", 46+I_1E, 1200 }, { "BNE", 47+I_1E, 1200 },
	{ "BZ", 46+I_1E, 1200 }, { "BNZ", 47+I_1E, 1200 },
	{ "BNL", 46+I_1E, 1300 }, { "BL", 47+I_1E, 1300 },
	{ "BNN", 46+I_1E, 1300 }, { "BN", 47+I_1E, 1300 },
	{ "BV", 46+I_1E, 1400 }, { "BNV", 47+I_1E, 1400 },
	{ "BXV", 46+I_1E, 1500 }, { "BNXV", 47+I_1E, 1500 },
	{ "BA", 46+I_1E, 1900 }, { "BNA", 47+I_1E, 1900 },
	{ "BNBS", 46+I_1E, 3000 }, { "BEBS", 47+I_1E, 3000 },
	{ "BBAS", 46+I_1E, 3100 }, { "BANS", 47+I_1E, 3100 },
	{ "BBBS", 46+I_1E, 3200 }, { "BBNS", 47+I_1E, 3200 },
	{ "BCH9", 46+I_1E, 3300 },
	{ "BCOV", 46+I_1E, 3400 },
	{ "BSNX", 60+I_1E, 0 }, { "BSBA", 60+I_1E, 1 },
	{ "BSBB", 60+I_1E, 2 },
	{ "BSNI", 60+I_1E, 8 }, { "BSIA", 60+I_1E, 9 },

	{ "FADD", 1+I_2, 0 }, { "FSUB", 2+I_2, 0 },
	{ "FMUL", 3+I_2, 0 }, { "FSL", 5+I_2, 0 },
	{ "TFL", 6+I_2, 0 }, { "BTFL", 7+I_2, 0 },
	{ "FSR", 8+I_2, 0 }, { "FDIV", 9+I_2, 0 },
	{ "BTAM", 10+I_2M, 0 }, { "AM", 11+I_2M, 0 },
	{ "SM", 12+I_2M, 0 }, { "MM", 13+I_2M, 0 },
	{ "CM", 14+I_2M, 0 }, { "TDM", 15+I_2S, 0 },
	{ "TFM", 16+I_2M, 0 }, { "BTM", 17+I_2M, 0 },
	{ "LDM", 18+I_2M, 0 }, { "DM", 19+I_2M, 0 },
	{ "BTA", 20+I_2, 0 }, { "A", 21+I_2, 0 },
	{ "S", 22+I_2, 0 }, { "M", 23+I_2, 0 },
	{ "C", 24+I_2, 0 }, { "TD", 25+I_2, 0 },
	{ "TF", 26+I_2, 0 }, { "BT", 27+I_2, 0 },
	{ "LD", 28+I_2, 0 }, { "D", 29+I_2, 0 },
	{ "TRNM", 30+I_2, 0 }, { "TR", 31+I_2, 0 },
	{ "SF", 32+I_1, 0 }, { "CF", 33+I_1, 0 },
	{ "K", 34+I_2S, 0 }, { "DN", 35+I_2S, 0 },
	{ "RN", 36+I_2S, 0 }, { "RA", 37+I_2S, 0 },
	{ "WN", 38+I_2S, 0 }, { "WA", 39+I_2S, 0 },
	{ "NOP", 41+I_0, 0 }, { "BB", 42+I_0, 0 },
	{ "BD", 43+I_2, 0 }, { "BNF", 44+I_2, 0 },
	{ "BNR", 45+I_2, 0 }, { "BI", 46+I_2S, 0 },
	{ "BNI", 47+I_2S, 0 }, { "H", 48+I_0, 0 },
	{ "B", 49+I_1, 0 }, { "BNG", 55+I_2, 0 },
	{ "BS", 60+I_2S, 0 }, { "BX", 61+I_2, 0 },
	{ "BXM", 62+I_2X, 0 }, { "BCX", 63+I_2, 0 },
	{ "BCXM", 64+I_2X, 0 }, { "BLX", 65+I_2, 0 },
	{ "BLXM", 66+I_2X, 0 }, { "BSX", 67+I_2, 0 },
	{ "MA", 70+I_2, 0 }, { "MF", 71+I_2, 0 },
	{ "TNS", 72+I_2, 0 }, { "TNF", 73+I_2, 0 },
	{ "BBT", 90+I_2, 0 }, { "BMK", 91+I_2, 0 },
	{ "ORF", 92+I_2, 0 }, { "ANDF", 93+I_2, 0 },
	{ "CPFL", 94+I_2, 0 }, { "EORF", 95+I_2, 0 },
	{ "OTD", 96+I_2, 0 }, { "DTO", 97+I_2, 0 },
	{ NULL, 0, 0 }
	};

	/* Print an address from five characters */

	/* Use scp.c provided fprintf function */
	#define fprintf Fprintf
	#define fputs(_s,f) Fprintf(f,"%s",_s)
	#define fputc(_c,f) Fprintf(f,"%c",_c)

	void fprint_addr (FILE of, int32 spc, t_value dig, t_bool flg)
	{
	int32 i, idx;

	fputc (spc, of); /* spacer */
	if (dig[ADDR_LEN - 1] & FLAG) { /* signed? */
	fputc ('-', of); /* print minus */
	dig[ADDR_LEN - 1] = dig[ADDR_LEN - 1] & ~FLAG;
	}
	for (i = 0; i < ADDR_LEN; i++) /* print digits */
	fprintf (of, "%X", dig[i] & DIGIT);
	if ((cpu_unit.flags & IF_IDX) && flg) { /* indexing? */
	for (i = idx = 0; i < ADDR_LEN - 2; i++) { /* get index reg */
	if (dig[ADDR_LEN - 2 - i] & FLAG)
	idx = idx \| (1 << i);
	dig[ADDR_LEN - 2 - i] = dig[ADDR_LEN - 2 - i] & ~FLAG;
	}
	if (idx) /* print */
	fprintf (of, "(%d)", idx);
	}
	return;
	}

	/* Symbolic decode

	Inputs:
	*of = output stream
	addr = current address
	*val = values to decode
	*uptr = pointer to unit
	sw = switches
	Outputs:
	return = if >= 0, error code
	if < 0, number of extra words retired
	*/

	#define FMTASC(x) ((x) < 040)? "<%03o>": "%c", (x)

	t_stat fprint_sym (FILE of, t_addr addr, t_value val,
	UNIT *uptr, int32 sw)
	{
	int32 pmp, qmp, i, c, d, any;
	uint32 op, qv, opfl;

	if (uptr == NULL)
	uptr = &cpu_unit;
	if (sw & SWMASK ('C')) { /* character? */
	if (uptr->flags & UNIT_BCD) {
	if (addr & 1) /* must be even */
	return SCPE_ARG;
	c = ((val[0] & DIGIT) << 4) \| (val[1] & DIGIT);
	if (alp_to_cdp[c] > 0)
	fprintf (of, "%c", alp_to_cdp[c]);
	else fprintf (of, "<%02x>", c);
	return -1;
	}
	else fprintf (of, FMTASC (val[0] & 0177));
	return SCPE_OK;
	}
	if ((uptr->flags & UNIT_BCD) == 0) /* CPU or disk? */
	return SCPE_ARG;
	if (sw & SWMASK ('D')) { /* dump? */
	for (i = d = 0; i < LINE_LNT; i++)
	d = d \| val[i];
	if (d & FLAG) { /* any flags? */
	for (i = 0; i < LINE_LNT; i++) /* print flags */
	fprintf (of, (val[i] & FLAG)? "_": " ");
	fprintf (of, "\n\t");
	}
	for (i = 0; i < LINE_LNT; i++) /* print digits */
	fprintf (of, "%X", val[i] & DIGIT) ;
	return -(i - 1);
	}
	if (sw & SWMASK ('S')) { /* string? */
	if (addr & 1) /* must be even */
	return SCPE_ARG;
	for (i = 0; i < LINE_LNT; i = i + 2) {
	c = ((val[i] & DIGIT) << 4) \| (val[i + 1] & DIGIT);
	if (alp_to_cdp[c] < 0)
	break;
	fprintf (of, "%c", alp_to_cdp[c]);
	}
	if (i == 0) {
	fprintf (of, "<%02X>", c);
	return -1;
	}
	return -(i - 1);
	}
	if ((sw & SWMASK ('M')) == 0)
	return SCPE_ARG;

	if (addr & 1) /* must be even */
	return SCPE_ARG;
	op = ((val[0] & DIGIT) * 10) + (val[1] & DIGIT); /* get opcode */
	for (i = qv = pmp = qmp = 0; i < ADDR_LEN; i++) { /* test addr */
	if (val[I_P + i])
	pmp = 1;
	if (val[I_Q + i])
	qmp = 1;
	qv = (qv * 10) + (val[I_Q + i] & DIGIT);
	}
	if ((val[0] \| val[1]) & FLAG) /* flags force */
	pmp = qmp = 1;
	for (i = 0; opcode[i].str != NULL; i++) { /* find opcode */
	opfl = opcode[i].opv & 0xFF0000;
	if ((op == (opcode[i].opv & 0xFF)) &&
	((qv == opcode[i].qv) \|\|
	((opfl != I_1E) && (opfl != I_0E))))
	break;
	}
	if (opcode[i].str == NULL)
	return SCPE_ARG;
	if (I_GETQP (opfl) == I_M_QNP) /* Q no print? */
	qmp = 0;

	fprintf (of, "%s", opcode[i].str); /* print opcode */
	if (I_GETPP (opfl) == I_M_PP) /* P required? */
	fprint_addr (of, ' ', &val[I_P], I_M_QX);
	else if ((I_GETPP (opfl) == I_M_PCP) && (pmp \|\| qmp)) /* P opt & needed? */
	fprint_addr (of, ' ', &val[I_P], 0);
	if (I_GETQP (opfl) == I_M_QP) { /* Q required? */
	fprint_addr (of, ',', &val[I_Q], I_GETQF (opfl));
	if (I_GETQF (opfl) & I_M_QM) /* immediate? */
	val[I_Q] = val[I_Q] & ~FLAG; /* clr hi Q flag */
	}
	else if ((I_GETQP (opfl) == I_M_QCP) && (pmp \|\| qmp)) /* Q opt & needed? */
	fprint_addr (of, ',', &val[I_Q], 0);
	for (i = any = 0; i < INST_LEN; i++) { /* print rem flags */
	if (val[i] & FLAG) {
	if (!any)
	fputc (',', of);
	any = 1;
	fprintf (of, "%d", i);
	}
	}
	return -(INST_LEN - 1);
	}

	/* parse_addr - get sign + address + index */

	t_stat parse_addr (char cptr, t_value val, int32 flg)
	{
	int32 i, sign = 0, addr, index;
	static int32 idx_tst[ADDR_LEN] = { 0, 4, 2, 1, 0 };
	char *tptr;

	if (cptr == '+') / +? skip */
	cptr++;
	else if (cptr == '-') { / -? skip, flag */
	sign = 1;
	cptr++;
	}
	errno = 0; /* get address */
	addr = strtoul (cptr, &tptr, 16);
	if (errno \|\| (cptr == tptr) \|\| (addr > 0xFFFFF)) /* err or too big? */
	return SCPE_ARG;
	if ((cpu_unit.flags & IF_IDX) && (flg & I_M_QX) && /* index allowed? */
	(tptr == '(')) { / index specified */
	errno = 0;
	index = strtoul (cptr = tptr + 1, &tptr, 10); /* get index */
	if (errno \|\| (cptr == tptr) \|\| (index > 7)) /* err or too big? */
	return SCPE_ARG;
	if (*tptr++ != ')')
	return SCPE_ARG;
	}
	else index = 0;
	if (tptr != 0) / all done? */
	return SCPE_ARG;
	for (i = ADDR_LEN - 1; i >= 0; i--) { /* cvt addr to dig */
	val[i] = (addr & 0xF) \| ((index & idx_tst[i])? FLAG: 0);
	addr = addr >> 4;
	}
	if (sign) /* set sign */
	val[ADDR_LEN - 1] = val[ADDR_LEN - 1] \| FLAG;
	if (flg & I_M_QM) /* set immediate */
	val[0] = val[0] \| FLAG;
	return SCPE_OK;
	}

	/* Symbolic input

	Inputs:
	*cptr = pointer to input string
	addr = current PC
	*uptr = pointer to unit
	*val = pointer to output values
	sw = switches
	Outputs:
	status = > 0 error code
	<= 0 -number of extra words
	*/

	t_stat parse_sym (char cptr, t_addr addr, UNIT uptr, t_value *val, int32 sw)
	{
	int32 i, qv, opfl, last;
	char la, *fptr, gbuf[CBUFSIZE];
	int8 t;

	while (isspace (cptr)) / absorb spaces */
	cptr++;
	if ((sw & SWMASK ('C')) \|\| ((cptr == '\'') && cptr++)) { / character? */
	if ((t = cptr & 0x7F) == 0) / get char */
	return SCPE_ARG;
	if (uptr->flags & UNIT_BCD) { /* BCD? */
	if (addr & 1)
	return SCPE_ARG;
	t = cdr_to_alp[t]; /* convert */
	if (t < 0) /* invalid? */
	return SCPE_ARG;
	val[0] = (t >> 4) & DIGIT; /* store */
	val[1] = t & DIGIT;
	return -1;
	}
	else val[0] = t; /* store ASCII */
	return SCPE_OK;
	}

	if ((uptr->flags & UNIT_BCD) == 0) /* CPU or disk? */
	return SCPE_ARG;
	if ((sw & SWMASK ('S')) \|\| ((cptr == '"') && cptr++)) { / string? */
	if (addr & 1) /* must be even */
	return SCPE_ARG;
	for (i = 0; (i < sim_emax) && (*cptr != 0); i = i + 2) {
	t = cptr++ & 0x7F; / get character */
	t = cdr_to_alp[t]; /* convert */
	if (t < 0) /* invalid? */
	return SCPE_ARG;
	val[i] = (t >> 4) & DIGIT; /* store */
	val[i + 1] = t & DIGIT;
	}
	if (i == 0) /* final check */
	return SCPE_ARG;
	return -(i - 1);
	}

	if (addr & 1) /* even addr? */
	return SCPE_ARG;
	cptr = get_glyph (cptr, gbuf, 0); /* get opcode */
	for (i = 0; opcode[i].str != NULL; i++) { /* look it up */
	if (strcmp (gbuf, opcode[i].str) == 0)
	break;
	}
	if (opcode[i].str == NULL) /* successful? */
	return SCPE_ARG;
	opfl = opcode[i].opv & 0xFF0000; /* get flags */
	val[0] = (opcode[i].opv & 0xFF) / 10; /* store opcode */
	val[1] = (opcode[i].opv & 0xFF) % 10;
	qv = opcode[i].qv;
	for (i = ADDR_LEN - 1; i >= 0; i--) { /* set P,Q fields */
	val[I_P + i] = 0;
	val[I_Q + i] = qv % 10;
	qv = qv /10;
	}

	cptr = get_glyph (cptr, gbuf, ','); /* get P field */
	if (gbuf[0]) { /* any? */
	if (parse_addr (gbuf, &val[I_P], (I_GETPP (opfl)? I_M_QX: 0)))
	return SCPE_ARG;
	}
	else if (I_GETPP (opfl) == I_M_PP)
	return SCPE_ARG;

	if (I_GETQP (opfl) != I_M_QNP) { /* Q field allowed? */
	cptr = get_glyph (cptr, gbuf, ','); /* get Q field */
	if (gbuf[0]) { /* any? */
	if (parse_addr (gbuf, &val[I_Q], I_GETQF (opfl)))
	return SCPE_ARG;
	}
	else if (I_GETQP (opfl) == I_M_QP)
	return SCPE_ARG;
	}

	cptr = get_glyph (cptr, fptr = gbuf, ' '); /* get flag field */
	last = -1; /* none yet */
	while ((t = fptr++)) { / loop through */
	if ((t < '0') \|\| (t > '9')) /* must be digit */
	return SCPE_ARG;
	t = t - '0'; /* convert */
	if (t == 1) { /* ambiguous? */
	la = fptr++; / get next */
	if (la == '0') /* 10? */
	t = 10;
	else if ((la == '1') && (fptr == 0)) / 11 & end field? */
	t = 11;
	else --fptr; /* dont lookahead */
	}
	if (t <= last) /* in order? */
	return SCPE_ARG;
	val[t] = val[t] \| FLAG; /* set flag */
	last = t; /* continue */
	}

	if (*cptr != 0)
	return SCPE_ARG;
	return -(INST_LEN - 1);
	}