ALL: Massive 'const' cleanup

These changes facilitate more robust parameter type checking and helps to identify unexpected coding errors. Most simulators can now also be compiled with a C++ compiler without warnings. Additionally, these changes have also been configured to facilitate easier backporting of simulator and device simulation modules to run under the simh v3.9+ SCP framework.
2026-04-04 21:07:39 +00:00 · 2016-05-15 15:25:33 -07:00
parent 60a8a2d43d
commit 5531ccb175
444 changed files with 4119 additions and 3798 deletions
--- a/PDP10/pdp10_cpu.c
+++ b/PDP10/pdp10_cpu.c
@@ -210,10 +210,10 @@ t_stat cpu_ex (t_value *vptr, t_addr addr, UNIT *uptr, int32 sw);
 t_stat cpu_dep (t_value val, t_addr addr, UNIT *uptr, int32 sw);
 t_stat cpu_reset (DEVICE *dptr);
 t_bool cpu_is_pc_a_subroutine_call (t_addr **ret_addrs);
-t_stat cpu_set_hist (UNIT *uptr, int32 val, char *cptr, void *desc);
-t_stat cpu_show_hist (FILE *st, UNIT *uptr, int32 val, void *desc);
-t_stat cpu_set_serial (UNIT *uptr, int32 val, char *cptr, void *desc);
-t_stat cpu_show_serial (FILE *st, UNIT *uptr, int32 val, void *desc);
+t_stat cpu_set_hist (UNIT *uptr, int32 val, CONST char *cptr, void *desc);
+t_stat cpu_show_hist (FILE *st, UNIT *uptr, int32 val, CONST void *desc);
+t_stat cpu_set_serial (UNIT *uptr, int32 val, CONST char *cptr, void *desc);
+t_stat cpu_show_serial (FILE *st, UNIT *uptr, int32 val, CONST void *desc);

 d10 adjsp (d10 val, a10 ea);
 void ibp (a10 ea, int32 pflgs);
@@ -253,7 +253,7 @@ int32 test_int (void);
 void set_ac_display (d10 *acbase);

 extern t_stat build_dib_tab (void);
-extern t_stat show_iospace (FILE *st, UNIT *uptr, int32 val, void *desc);
+extern t_stat show_iospace (FILE *st, UNIT *uptr, int32 val, CONST void *desc);
 extern d10 Read (a10 ea, int32 prv);                    /* read, read check */
 extern d10 ReadM (a10 ea, int32 prv);                   /* read, write check */
 extern d10 ReadE (a10 ea);                              /* read, exec */
@@ -328,7 +328,7 @@ extern t_bool wrpcst (a10 ea, int32 prv);
 extern t_bool spm (a10 ea, int32 prv);
 extern t_bool lpmr (a10 ea, int32 prv);
 extern int32 pi_ub_vec (int32 lvl, int32 *uba);
-extern t_stat tim_set_mod (UNIT *uptr, int32 val, char *cptr, void *desc);
+extern t_stat tim_set_mod (UNIT *uptr, int32 val, CONST char *cptr, void *desc);

 /* CPU data structures

@@ -2505,7 +2505,7 @@ return;

 /* Set history */

-t_stat cpu_set_hist (UNIT *uptr, int32 val, char *cptr, void *desc)
+t_stat cpu_set_hist (UNIT *uptr, int32 val, CONST char *cptr, void *desc)
 {
 int32 i, lnt;
 t_stat r;
@@ -2536,10 +2536,10 @@ return SCPE_OK;

 /* Show history */

-t_stat cpu_show_hist (FILE *st, UNIT *uptr, int32 val, void *desc)
+t_stat cpu_show_hist (FILE *st, UNIT *uptr, int32 val, CONST void *desc)
 {
 int32 k, di, lnt;
-char *cptr = (char *) desc;
+const char *cptr = (const char *) desc;
 t_stat r;
 t_value sim_eval;
 InstHistory *h;
@@ -2576,7 +2576,7 @@ return SCPE_OK;

 /* Set serial */

-t_stat cpu_set_serial (UNIT *uptr, int32 val, char *cptr, void *desc)
+t_stat cpu_set_serial (UNIT *uptr, int32 val, CONST char *cptr, void *desc)
 {
 int32 lnt;
 t_stat r;
@@ -2594,7 +2594,7 @@ return SCPE_OK;

 /* Show serial */

-t_stat cpu_show_serial (FILE *st, UNIT *uptr, int32 val, void *desc)
+t_stat cpu_show_serial (FILE *st, UNIT *uptr, int32 val, CONST void *desc)
 {
 fprintf (st, "Serial: " );
 if( (apr_serial == -1) || (!Q_ITS && apr_serial < 4096) ) {
--- a/PDP10/pdp10_defs.h
+++ b/PDP10/pdp10_defs.h
@@ -766,20 +766,24 @@ typedef struct pdp_dib DIB;
 int32 Map_ReadB (uint32 ba, int32 bc, uint8 *buf);
 int32 Map_ReadW (uint32 ba, int32 bc, uint16 *buf);
 int32 Map_ReadW18 (uint32 ba, int32 bc, uint32 *buf);
-int32 Map_WriteB (uint32 ba, int32 bc, uint8 *buf);
-int32 Map_WriteW (uint32 ba, int32 bc, uint16 *buf);
-int32 Map_WriteW18 (uint32 ba, int32 bc, uint32 *buf);
+int32 Map_WriteB (uint32 ba, int32 bc, const uint8 *buf);
+int32 Map_WriteW (uint32 ba, int32 bc, const uint16 *buf);
+int32 Map_WriteW18 (uint32 ba, int32 bc, const uint32 *buf);
 void uba_debug_dma_in (uint32 ba, a10 pa_start, a10 pa_end);
 void uba_debug_dma_out (uint32 ba, a10 pa_start, a10 pa_end);
 void uba_debug_dma_nxm (const char *msg, a10 pa10, uint32 ba, int32 bc);

-t_stat set_addr (UNIT *uptr, int32 val, char *cptr, void *desc);
-t_stat set_addr_flt (UNIT *uptr, int32 val, char *cptr, void *desc);
-t_stat show_addr (FILE *st, UNIT *uptr, int32 val, void *desc);
-t_stat set_vec (UNIT *uptr, int32 val, char *cptr, void *desc);
-t_stat show_vec (FILE *st, UNIT *uptr, int32 val, void *desc);
-t_stat show_vec_mux (FILE *st, UNIT *uptr, int32 val, void *desc);
+t_stat set_addr (UNIT *uptr, int32 val, CONST char *cptr, void *desc);
+t_stat set_addr_flt (UNIT *uptr, int32 val, CONST char *cptr, void *desc);
+t_stat show_addr (FILE *st, UNIT *uptr, int32 val, CONST void *desc);
+t_stat set_vec (UNIT *uptr, int32 val, CONST char *cptr, void *desc);
+t_stat show_vec (FILE *st, UNIT *uptr, int32 val, CONST void *desc);
+t_stat show_vec_mux (FILE *st, UNIT *uptr, int32 val, CONST void *desc);
 t_stat auto_config (const char *name, int32 num);

+extern d10 *ac_cur;                                     /* current AC block */
+extern int32 flags;                                     /* flags */
+extern const int32 pi_l2bit[8];
+extern const d10 bytemask[64];

 #endif
--- a/PDP10/pdp10_fe.c
+++ b/PDP10/pdp10_fe.c
@@ -49,7 +49,7 @@ t_stat fei_svc (UNIT *uptr);
 t_stat feo_svc (UNIT *uptr);
 static t_stat kaf_svc (UNIT *uptr);
 t_stat fe_reset (DEVICE *dptr);
-t_stat fe_stop_os (UNIT *uptr, int32 val, char *cptr, void *desc);
+t_stat fe_stop_os (UNIT *uptr, int32 val, CONST char *cptr, void *desc);
 a10 fe_xct = 0;
 uint32 fe_bootrh = 0;
 int32 fe_bootunit = -1;
@@ -307,7 +307,7 @@ return SCPE_OK;

 /* Stop operating system */

-t_stat fe_stop_os (UNIT *uptr, int32 val, char *cptr, void *desc)
+t_stat fe_stop_os (UNIT *uptr, int32 val, CONST char *cptr, void *desc)
 {
 M[FE_SWITCH] = IOBA_RP;                                 /* tell OS to stop */
 return SCPE_OK;
--- a/PDP10/pdp10_ksio.c
+++ b/PDP10/pdp10_ksio.c
@@ -150,10 +150,7 @@ static const int32 ubabr54[UBANUM] = {
 #define M_WORD1 (~INT64_C (0000000777777)) /* Clear word 1 + XX */

 extern d10 *M;                                          /* main memory */
-extern d10 *ac_cur;
 extern d10 pager_word;
-extern int32 flags;
-extern const int32 pi_l2bit[8];
 extern UNIT cpu_unit;
 extern jmp_buf save_env;

@@ -1036,7 +1033,7 @@ return 0;

 /* Byte-mode writes */

-int32 Map_WriteB (uint32 ba, int32 bc, uint8 *buf)
+int32 Map_WriteB (uint32 ba, int32 bc, const uint8 *buf)
 {
 uint32 ea, ofs, cp, np;
 int32 seg, ubm = 0;
@@ -1183,7 +1180,7 @@ return 0;

 /* Word mode writes; 16-bit data */

-int32 Map_WriteW (uint32 ba, int32 bc, uint16 *buf)
+int32 Map_WriteW (uint32 ba, int32 bc, const uint16 *buf)
 {
 uint32 ea, cp, np;
 int32 seg, ubm = 0;
@@ -1295,7 +1292,7 @@ return 0;

 /* Word mode writes; 18-bit data */

-int32 Map_WriteW18 (uint32 ba, int32 bc, uint32 *buf)
+int32 Map_WriteW18 (uint32 ba, int32 bc, const uint32 *buf)
 {
 uint32 ea, cp, np;
 int32 seg, ubm = 0;
@@ -1404,7 +1401,7 @@ return 0;

 /* Word mode writes; 36-bit data */

-int32 Map_WriteW36 (uint32 ba, int32 bc, a10 *buf)
+int32 Map_WriteW36 (uint32 ba, int32 bc, const a10 *buf)
 {
 uint32 ea, cp, np;
 int32 seg, ubm = 0;
@@ -1699,7 +1696,7 @@ return SCPE_OK;

 /* Change device address */

-t_stat set_addr (UNIT *uptr, int32 val, char *cptr, void *desc)
+t_stat set_addr (UNIT *uptr, int32 val, CONST char *cptr, void *desc)
 {
 DEVICE *dptr;
 DIB *dibp;
@@ -1730,7 +1727,7 @@ return SCPE_OK;

 /* Show device address */

-t_stat show_addr (FILE *st, UNIT *uptr, int32 val, void *desc)
+t_stat show_addr (FILE *st, UNIT *uptr, int32 val, CONST void *desc)
 {
 DEVICE *dptr;
 DIB *dibp;
@@ -1756,7 +1753,7 @@ return SCPE_OK;

 /* Change device vector */

-t_stat set_vec (UNIT *uptr, int32 arg, char *cptr, void *desc)
+t_stat set_vec (UNIT *uptr, int32 arg, CONST char *cptr, void *desc)
 {
 DEVICE *dptr;
 DIB *dibp;
@@ -1785,7 +1782,7 @@ return SCPE_OK;

 /* Show device vector */

-t_stat show_vec (FILE *st, UNIT *uptr, int32 arg, void *desc)
+t_stat show_vec (FILE *st, UNIT *uptr, int32 arg, CONST void *desc)
 {
 DEVICE *dptr;
 DIB *dibp;
@@ -1817,9 +1814,9 @@ return SCPE_OK;

 /* Show vector for terminal multiplexor */

-t_stat show_vec_mux (FILE *st, UNIT *uptr, int32 arg, void *desc)
+t_stat show_vec_mux (FILE *st, UNIT *uptr, int32 arg, CONST void *desc)
 {
-TMXR *mp = (TMXR *) desc;
+const TMXR *mp = (const TMXR *) desc;

 if ((mp == NULL) || (arg == 0))
    return SCPE_IERR;
@@ -1904,7 +1901,7 @@ return SCPE_OK;

 /* Show dib_tab */

-t_stat show_iospace (FILE *st, UNIT *uptr, int32 val, void *desc)
+t_stat show_iospace (FILE *st, UNIT *uptr, int32 val, CONST void *desc)
 {
 int32 i, j, done = 0;
 DEVICE *dptr;
@@ -1976,7 +1973,7 @@ return SCPE_OK;


 typedef struct {
-    char        *dnam[AUTO_MAXC];
+    const char  *dnam[AUTO_MAXC];
    int32       numc;
    int32       numv;
    uint32      amod;
@@ -2281,7 +2278,7 @@ return SCPE_OK;

 /* Set address floating */

-t_stat set_addr_flt (UNIT *uptr, int32 val, char *cptr, void *desc)
+t_stat set_addr_flt (UNIT *uptr, int32 val, CONST char *cptr, void *desc)
 {
 DEVICE *dptr;

--- a/PDP10/pdp10_lp20.c
+++ b/PDP10/pdp10_lp20.c
@@ -193,7 +193,6 @@ static int32 lpi = DEFAULT_LPI;                         /* Printer's LPI. */
 static int16 txram[TX_SIZE] = { 0 };                    /* translation RAM */
 static int16 davfu[DV_SIZE] = { 0 };                    /* DAVFU */

-DEVICE lp20_dev;
 static t_stat lp20_rd (int32 *data, int32 pa, int32 access);
 static t_stat lp20_wr (int32 data, int32 pa, int32 access);
 static int32 lp20_inta (void);
@@ -202,15 +201,15 @@ static t_stat idle_svc (UNIT *uptr);
 static void set_flush_timer (UNIT *uptr);
 static t_stat lp20_reset (DEVICE *dptr);
 static t_stat lp20_init (DEVICE *dptr);
-static t_stat lp20_attach (UNIT *uptr, char *ptr);
+static t_stat lp20_attach (UNIT *uptr, CONST char *ptr);
 static t_stat lp20_detach (UNIT *uptr);
-static t_stat lp20_set_lpi (UNIT *uptr, int32 val, char *cptr, void *desc);
-static t_stat lp20_show_lpi (FILE *st, UNIT *up, int32 v, void *dp);
-static t_stat lp20_set_vfu_type (UNIT *uptr, int32 val, char *cptr, void *desc);
-static t_stat lp20_show_vfu_type (FILE *st, UNIT *up, int32 v, void *dp);
-static t_stat lp20_show_vfu (FILE *st, UNIT *up, int32 v, void *dp);
-static t_stat lp20_set_tof (UNIT *uptr, int32 val, char *cptr, void *desc);
-static t_stat lp20_clear_vfu (UNIT *uptr, int32 val, char *cptr, void *desc);
+static t_stat lp20_set_lpi (UNIT *uptr, int32 val, CONST char *cptr, void *desc);
+static t_stat lp20_show_lpi (FILE *st, UNIT *up, int32 v, CONST void *dp);
+static t_stat lp20_set_vfu_type (UNIT *uptr, int32 val, CONST char *cptr, void *desc);
+static t_stat lp20_show_vfu_type (FILE *st, UNIT *up, int32 v, CONST void *dp);
+static t_stat lp20_show_vfu (FILE *st, UNIT *up, int32 v, CONST void *dp);
+static t_stat lp20_set_tof (UNIT *uptr, int32 val, CONST char *cptr, void *desc);
+static t_stat lp20_clear_vfu (UNIT *uptr, int32 val, CONST char *cptr, void *desc);
 static t_bool lp20_print (int32 c);
 static t_bool lp20_adv (int32 c, t_bool advdvu);
 static t_bool lp20_davfu (int32 c);
@@ -341,14 +340,9 @@ static DIB lp20_dib = {
 * product'.  It's not implemented in this emulation.
 */

-static UNIT lp20_idle;
-static UNIT lp20_unit = {
-    UDATA (&lp20_svc, UNIT_SEQ+UNIT_ATTABLE+UNIT_TEXT, 0), SERIAL_OUT_WAIT,
-           0, 0, 0, 0, &lp20_idle,
-    };
-static UNIT lp20_idle = {
-    UDATA (&idle_svc, UNIT_DIS, 0), 1000000, LP20_IDLE_TIME,
-           0, 0, 0, &lp20_unit,
+static UNIT lp20_unit[] = {
+    {UDATA (&lp20_svc, UNIT_SEQ+UNIT_ATTABLE+UNIT_TEXT, 0), SERIAL_OUT_WAIT},
+    {UDATA (&idle_svc, UNIT_DIS, 0), 1000000, LP20_IDLE_TIME}
    };

 static REG lp20_reg[] = {
@@ -371,8 +365,8 @@ static REG lp20_reg[] = {
    { FLDATAD (ERR, lpcsa, CSR_V_ERR, "error flag") },
    { FLDATAD (DONE, lpcsa, CSR_V_DONE, "done flag") },
    { FLDATAD (IE, lpcsa, CSR_V_IE, "interrupt enable flag") },
-    { DRDATAD (POS, lp20_unit.pos, T_ADDR_W, "position in output file"), PV_LEFT },
-    { DRDATAD (TIME, lp20_unit.wait, 24, "response time"), PV_LEFT },
+    { DRDATAD (POS, lp20_unit[0].pos, T_ADDR_W, "position in output file"), PV_LEFT },
+    { DRDATAD (TIME, lp20_unit[0].wait, 24, "response time"), PV_LEFT },
    { FLDATAD (STOP_IOE, lp20_stopioe, 0, "stop on I/O error") },
    { BRDATAD (TXRAM, txram, 8, 13, TX_SIZE, "translation RAM") },
    { BRDATAD (DAVFU, davfu, 8, 12, DV_SIZE, "vertical forms unit array") },
@@ -401,8 +395,8 @@ static MTAB lp20_mod[] = {
    };

 DEVICE lp20_dev = {
-    "LP20", &lp20_unit, lp20_reg, lp20_mod,
-    1, 10, 31, 1, 8, 8,
+    "LP20", lp20_unit, lp20_reg, lp20_mod,
+    2, 10, 31, 1, 8, 8,
    NULL, NULL, &lp20_reset,
    NULL, &lp20_attach, &lp20_detach,
    &lp20_dib, DEV_DISABLE | DEV_UBUS, 0,
@@ -484,7 +478,7 @@ switch ((pa >> 1) & 07) {                               /* case on PA<3:1> */
        if (data & CSA_ECLR) {                          /* error clear? */
            lpcsa = (lpcsa | CSA_DONE) & ~CSA_GO;       /* set done, clr go */
            lpcsb = lpcsb & ~CSB_ECLR;                  /* clear err */
-            sim_cancel (&lp20_unit);                    /* cancel I/O */
+            sim_cancel (lp20_unit);                     /* cancel I/O */
            }
        if (data & CSA_INIT)                            /* init? */
            lp20_init (&lp20_dev);
@@ -493,10 +487,10 @@ switch ((pa >> 1) & 07) {                               /* case on PA<3:1> */
                if (lpcsb & CSB_ERR)
                    lpcsb = lpcsb | CSB_GOE;
                lpcsum = 0;                             /* clear checksum */
-                sim_activate (&lp20_unit, lp20_unit.wait);
+                sim_activate (lp20_unit, lp20_unit->wait);
                }
            }
-        else sim_cancel (&lp20_unit);                   /* go clr, stop DMA */
+        else sim_cancel (lp20_unit);                    /* go clr, stop DMA */
        lpcsa = (lpcsa & ~CSA_RW) | (data & CSA_RW);
        if (dvld && (CSA_GETFNC (lpcsa) != FNC_DVU)) {  /* DVU load aborted */
            change_rdy (0, CSA_DVON);                   /* Mark DVU off-line and empty */
@@ -598,7 +592,7 @@ lpcsa = lpcsa & ~CSA_GO;
 ba = CSA_GETUAE (lpcsa) | lpba;
 fnc = CSA_GETFNC (lpcsa);
 tbc = 010000 - lpbc;
-if (((fnc & FNC_INTERNAL) == 0) && ((lp20_unit.flags & UNIT_ATT) == 0)) {
+if (((fnc & FNC_INTERNAL) == 0) && ((uptr->flags & UNIT_ATT) == 0)) {
    update_lpcs (CSA_ERR);
    return IORETURN (lp20_stopioe, SCPE_UNATT);
    }
@@ -724,16 +718,16 @@ for (i = 0, cont = TRUE; (i < tbc) && cont; ba++, i++) {
        }                                               /* end case function */
    }                                                   /* end for */
 if (lpcolc == 0)
-    set_flush_timer (&lp20_unit);
+    set_flush_timer (uptr);
 else
-    sim_cancel ((UNIT *)lp20_unit.up7);
+    sim_cancel (uptr+1);
 lpba = ba & 0177777;
 lpcsa = (lpcsa & ~CSA_UAE) | ((ba >> (16 - CSA_V_UAE)) & CSA_UAE);
 lpbc = (lpbc + i) & BC_MASK;
 if (lpbc)                                               /* intr, but not done */
    update_lpcs (CSA_MBZ);
 else update_lpcs (CSA_DONE);                            /* intr and done */
-if ((fnc == FNC_PR) && ferror (lp20_unit.fileref)) {
+if ((fnc == FNC_PR) && ferror (uptr->fileref)) {
    sim_perror ("LP I/O error");
    clearerr (uptr->fileref);
    return SCPE_IOERR;
@@ -779,8 +773,8 @@ else {
        r = lp20_adv (1, TRUE);                         /* adv carriage */
    }
 for (i = 0; i < rpt; i++)
-    fputc (lppdat, lp20_unit.fileref); 
-lp20_unit.pos = (t_addr)sim_ftell (lp20_unit.fileref);
+    fputc (lppdat, lp20_unit->fileref); 
+lp20_unit->pos = (t_addr)sim_ftell (lp20_unit->fileref);
 lpcolc = lpcolc + rpt;
 return r;
 }
@@ -804,7 +798,7 @@ if (lpcsb & CSB_DVOF)

 lpcolc = 0;                                             /* reset col cntr */
 for (i = 0; i < cnt; i++) {                             /* print 'n' newlines; each can complete a page */
-    fputc ('\n', lp20_unit.fileref);
+    fputc ('\n', lp20_unit->fileref);
    if (dvuadv) {                                       /* update DAVFU ptr */
        dvptr = (dvptr + cnt) % dvlnt;
        if (davfu[dvptr] & (1 << DV_TOF)) {              /* at top of form? */
@@ -816,7 +810,7 @@ for (i = 0; i < cnt; i++) {                             /* print 'n' newlines; e
            } /* At TOF */
        } /* update pointer */
    }
-lp20_unit.pos = (t_addr)sim_ftell (lp20_unit.fileref);
+lp20_unit->pos = (t_addr)sim_ftell (lp20_unit->fileref);
 if (stoppc)                                            /* Crossed one or more TOFs? */
    return FALSE;

@@ -840,8 +834,8 @@ for (i = 0; i < dvlnt; i++) {                           /* search DAVFU */
            return lp20_adv (i + 1, FALSE);
        if (lpcolc)                                     /* TOF, need newline? */
            lp20_adv (1, FALSE);
-        fputc ('\f', lp20_unit.fileref);                /* print form feed */
-        lp20_unit.pos = (t_addr)sim_ftell (lp20_unit.fileref);
+        fputc ('\f', lp20_unit->fileref);               /* print form feed */
+        lp20_unit->pos = (t_addr)sim_ftell (lp20_unit->fileref);
        lppagc = (lppagc - 1) & PAGC_MASK;              /* decr page cntr */
        if (lppagc != 0)
            return TRUE;
@@ -863,7 +857,7 @@ if (flg)                                                /* set int req */
    lp20_irq = 1;
 lpcsa = (lpcsa | flg) & ~(CSA_MBZ | CSA_ERR | CSA_ONL);
 lpcsb = (lpcsb | CSB_OFFL) & ~CSB_MBZ;
-if (lp20_unit.flags & UNIT_ATT) {
+if (lp20_unit->flags & UNIT_ATT) {
    lpcsa = lpcsa | CSA_ONL;
    lpcsb = lpcsb & ~CSB_OFFL;
    }
@@ -884,7 +878,7 @@ static void change_rdy (int32 setrdy, int32 clrrdy)
 {
 int32 newcsa = (lpcsa | setrdy) & ~clrrdy;

-if ((newcsa ^ lpcsa) & (CSA_ONL | CSA_DVON) && !sim_is_active (&lp20_unit)) {
+if ((newcsa ^ lpcsa) & (CSA_ONL | CSA_DVON) && !sim_is_active (lp20_unit)) {
    lp20_irq |= 1;
    if (newcsa & CSA_IE)
        SET_INT(LP20);
@@ -945,16 +939,16 @@ lpcsb = lpcsb & (CSB_OVFU | CSB_DVOF);
 lpba = lpbc = lppagc = lpcolc = 0;                      /* clear registers */
 lprdat = lppdat = lpcbuf = lpcsum = 0;
 lp20_irq = 0;                                           /* clear int req */
-sim_cancel (&lp20_unit);                                /* deactivate unit */
-if (sim_is_active ((UNIT *)lp20_unit.up7)) {
-    fflush (lp20_unit.fileref);
-    sim_cancel ((UNIT *)lp20_unit.up7);
+sim_cancel (lp20_unit);                                /* deactivate unit */
+if (sim_is_active (lp20_unit+1)) {
+    fflush (lp20_unit->fileref);
+    sim_cancel (lp20_unit+1);
    }
 update_lpcs (0);                                        /* update status */
 return SCPE_OK;
 }

-static t_stat lp20_attach (UNIT *uptr, char *cptr)
+static t_stat lp20_attach (UNIT *uptr, CONST char *cptr)
 {
 t_stat reason;
    
@@ -975,7 +969,7 @@ if (lpcsa & CSA_DVON) {
 }
 if (lpcsa & CSA_ONL)                                    /* just file chg? */
    return reason;
-if (sim_is_active (&lp20_unit))                         /* busy? no int */
+if (sim_is_active (lp20_unit))                          /* busy? no int */
    update_lpcs (0);
 else update_lpcs (CSA_MBZ);                             /* interrupt */
 return reason;
@@ -987,12 +981,12 @@ t_stat reason;

 if (!(uptr->flags & UNIT_ATT))                          /* attached? */
    return SCPE_OK;
-if (sim_is_active ((UNIT *)lp20_unit.up7)) {
-    fflush (lp20_unit.fileref);
-    sim_cancel ((UNIT *)lp20_unit.up7);
+if (sim_is_active (lp20_unit+1)) {
+    fflush (lp20_unit->fileref);
+    sim_cancel (lp20_unit+1);
 }
 reason = detach_unit (uptr);
-sim_cancel (&lp20_unit);
+sim_cancel (lp20_unit);
 lpcsa = lpcsa & ~CSA_GO;
 update_lpcs (CSA_MBZ);
 return reason;
@@ -1022,15 +1016,20 @@ fflush (uptr->fileref);
 return SCPE_OK;
 }

-static t_stat lp20_set_vfu_type (UNIT *uptr, int32 val, char *cptr, void *desc)
+static t_stat lp20_set_vfu_type (UNIT *uptr, int32 val, CONST char *gptr, void *desc)
 {
+char gbuf[CBUFSIZE], *cptr;
 char *fname, *cp;
 FILE *vfile;
 int sum = 0;

-if (!cptr || !*cptr)
+if (!gptr || !*gptr)
    return SCPE_ARG;

+gbuf[sizeof(gbuf)-1] = '\0';
+strncpy (gbuf, gptr, sizeof(gbuf)-1);
+cptr = gbuf;
+
 fname = strchr (cptr, '=');
 if (fname)
    *fname++ = '\0';
@@ -1148,7 +1147,7 @@ fclose(vfile);
 return SCPE_FMT;
 }

-static t_stat lp20_show_vfu_type (FILE *st, UNIT *up, int32 v, void *dp)
+static t_stat lp20_show_vfu_type (FILE *st, UNIT *up, int32 v, CONST void *dp)
 {
 if (lpcsb & CSB_OVFU)
    fprintf (st, "optical VFU");
@@ -1163,7 +1162,7 @@ else
 return SCPE_OK;
 }

-static t_stat lp20_set_lpi (UNIT *uptr, int32 val, char *cptr, void *desc)
+static t_stat lp20_set_lpi (UNIT *uptr, int32 val, CONST char *cptr, void *desc)
 {
 int32 newlpi;

@@ -1186,14 +1185,14 @@ lpi = newlpi;
 return SCPE_OK;
 }

-static t_stat lp20_show_lpi (FILE *st, UNIT *up, int32 v, void *dp)
+static t_stat lp20_show_lpi (FILE *st, UNIT *up, int32 v, CONST void *dp)
 {
 fprintf (st, "%u LPI", lpi);

 return SCPE_OK;
 }

-static t_stat lp20_show_vfu (FILE *st, UNIT *up, int32 v, void *dp)
+static t_stat lp20_show_vfu (FILE *st, UNIT *up, int32 v, CONST void *dp)
 {
 int l, c, sum;

@@ -1231,7 +1230,7 @@ if (!(sum & (1 << DV_BOF))) {

 return SCPE_OK;
 }
-static t_stat lp20_set_tof (UNIT *uptr, int32 val, char *cptr, void *desc)
+static t_stat lp20_set_tof (UNIT *uptr, int32 val, CONST char *cptr, void *desc)
 {
 int32 s_lpcsa = lpcsa;
 int32 s_lppagc = lppagc;
@@ -1262,7 +1261,7 @@ while (value) {
 return even;
 }

-static t_stat lp20_clear_vfu (UNIT *uptr, int32 val, char *cptr, void *desc)
+static t_stat lp20_clear_vfu (UNIT *uptr, int32 val, CONST char *cptr, void *desc)
 {
 int i;

--- a/PDP10/pdp10_mdfp.c
+++ b/PDP10/pdp10_mdfp.c
@@ -154,8 +154,6 @@ typedef struct {                                        /* unpacked fp number */
 #define UNEG(x)         ((~x) + 1)
 #define DUNEG(x)        x.flo = UNEG (x.flo); x.fhi = ~x.fhi + (x.flo == 0)

-extern d10 *ac_cur;                                     /* current AC block */
-extern int32 flags;                                     /* flags */
 void mul (d10 a, d10 b, d10 *rs);
 void funpack (d10 h, d10 l, UFP *r, t_bool sgn);
 void fnorm (UFP *r, t_int64 rnd);
--- a/PDP10/pdp10_pag.c
+++ b/PDP10/pdp10_pag.c
@@ -97,9 +97,8 @@

 extern d10 *M;
 extern d10 acs[AC_NBLK * AC_NUM];
-extern d10 *ac_cur, *ac_prv, *last_pa;
+extern d10 *ac_prv, *last_pa;
 extern a10 epta, upta;
-extern int32 flags;
 extern d10 pager_word;
 extern int32 apr_flg;
 extern d10 ebr, ubr, hsb;
--- a/PDP10/pdp10_rp.c
+++ b/PDP10/pdp10_rp.c
@@ -370,12 +370,12 @@ int32 rp_inta (void);
 t_stat rp_svc (UNIT *uptr);
 t_stat rp_reset (DEVICE *dptr);
 t_stat rp_boot (int32 unitno, DEVICE *dptr);
-t_stat rp_attach (UNIT *uptr, char *cptr);
+t_stat rp_attach (UNIT *uptr, CONST char *cptr);
 t_stat rp_detach (UNIT *uptr);
 void set_rper (int16 flag, int32 drv);
 void update_rpcs (int32 flags, int32 drv);
 void rp_go (int32 drv, int32 fnc);
-t_stat rp_set_size (UNIT *uptr, int32 val, char *cptr, void *desc);
+t_stat rp_set_size (UNIT *uptr, int32 val, CONST char *cptr, void *desc);

 /* RP data structures

@@ -1150,7 +1150,7 @@ return SCPE_OK;

 /* Device attach */

-t_stat rp_attach (UNIT *uptr, char *cptr)
+t_stat rp_attach (UNIT *uptr, CONST char *cptr)
 {
 int32 i, p;
 t_stat r;
@@ -1203,7 +1203,7 @@ return detach_unit (uptr);

 /* Set size command validation routine */

-t_stat rp_set_size (UNIT *uptr, int32 val, char *cptr, void *desc)
+t_stat rp_set_size (UNIT *uptr, int32 val, CONST char *cptr, void *desc)
 {
 int32 dtype = GET_DTYPE (val);

--- a/PDP10/pdp10_sys.c
+++ b/PDP10/pdp10_sys.c
@@ -344,7 +344,7 @@ return SCPE_OK;

 /* Master loader */

-t_stat sim_load (FILE *fileref, char *cptr, char *fnam, int flag)
+t_stat sim_load (FILE *fileref, CONST char *cptr, CONST char *fnam, int flag)
 {
 d10 data;
 int32 wc, fmt;
@@ -782,11 +782,11 @@ return SCPE_ARG;
        val     =       output value
 */

-t_value get_opnd (char *cptr, t_stat *status)
+t_value get_opnd (CONST char *cptr, t_stat *status)
 {
 int32 sign = 0;
 t_value val, xr = 0, ind = 0;
-const char *tptr;
+CONST char *tptr;

 *status = SCPE_ARG;                                     /* assume fail */
 if (*cptr == '@') {
@@ -804,14 +804,14 @@ if (val > 0777777)
    return 0;
 if (sign)
    val = (~val + 1) & 0777777;
-cptr = (char *)tptr;
+cptr = tptr;
 if (*cptr == '(') {
    cptr++;
    xr = strtotv (cptr, &tptr, 8);
    if ((cptr == tptr) || (*tptr != ')') ||
        (xr > AC_NUM) || (xr == 0))
        return 0;
-    cptr = (char *)++tptr;
+    cptr = ++tptr;
    }
 if (*cptr == 0)
    *status = SCPE_OK;
@@ -830,20 +830,17 @@ return (ind | (xr << 18) | val);
        status  =       error status
 */

-t_stat parse_sym (char *cptr, t_addr addr, UNIT *uptr, t_value *val, int32 sw)
+t_stat parse_sym (CONST char *cptr, t_addr addr, UNIT *uptr, t_value *val, int32 sw)
 {
 int32 i, j;
 t_value ac, dev;
 t_stat r;
-char gbuf[CBUFSIZE];
+char gbuf[CBUFSIZE], cbuf[2*CBUFSIZE];

 while (isspace (*cptr)) cptr++;
-for (i = 0; i < 6; i++) {
-    if (cptr[i] == 0) {
-        for (j = i + 1; j <= 6; j++) cptr[j] = 0;
-        break;
-        }
-    }
+memset (cbuf, '\0', sizeof(cbuf));
+strncpy (cbuf, cptr, sizeof(cbuf)-7);
+cptr = cbuf;
 if ((sw & SWMASK ('A')) || ((*cptr == '\'') && cptr++)) { /* ASCII char? */
    if (cptr[0] == 0)                                   /* must have 1 char */
        return SCPE_ARG;
--- a/PDP10/pdp10_tim.c
+++ b/PDP10/pdp10_tim.c
@@ -145,7 +145,6 @@ extern d10 pcst;
 extern a10 pager_PC;
 extern int32 t20_idlelock;

-DEVICE tim_dev;
 static t_stat tcu_rd (int32 *data, int32 PA, int32 access);
 static t_stat tim_svc (UNIT *uptr);
 static t_stat tim_reset (DEVICE *dptr);
@@ -378,7 +377,7 @@ return SCPE_OK;

 /* Set timer parameters from CPU model */

-t_stat tim_set_mod (UNIT *uptr, int32 val, char *cptr, void *desc)
+t_stat tim_set_mod (UNIT *uptr, int32 val, CONST char *cptr, void *desc)
 {
 if (val & (UNIT_T20|UNIT_KLAD)) {
    clk_tps = TIM_TPS_T20;
--- a/PDP10/pdp10_tu.c
+++ b/PDP10/pdp10_tu.c
@@ -328,7 +328,7 @@ int32 reg_in_fmtr1[32] = {                              /* rmr if write + go */
 int32 fmt_test[16] = {                                  /* fmt bytes/10 wd */
    5, 0, 5, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
    };
-static char *tu_fname[CS1_N_FNC] = {
+static const char *tu_fname[CS1_N_FNC] = {
    "NOP", "UNLD", "2", "REW", "FCLR", "5", "6", "7",
    "RIP", "11", "ERASE", "WREOF", "SPCF", "SPCR", "16", "17",
    "20", "21", "22", "23", "WRCHKF", "25", "26", "WRCHKR",
@@ -341,7 +341,7 @@ t_stat tu_wr (int32 data, int32 PA, int32 access);
 int32 tu_inta (void);
 t_stat tu_svc (UNIT *uptr);
 t_stat tu_reset (DEVICE *dptr);
-t_stat tu_attach (UNIT *uptr, char *cptr);
+t_stat tu_attach (UNIT *uptr, CONST char *cptr);
 t_stat tu_detach (UNIT *uptr);
 t_stat tu_boot (int32 unitno, DEVICE *dptr);
 void tu_go (int32 drv);
@@ -1179,7 +1179,7 @@ return SCPE_OK;

 /* Attach routine */

-t_stat tu_attach (UNIT *uptr, char *cptr)
+t_stat tu_attach (UNIT *uptr, CONST char *cptr)
 {
 int32 drv = uptr - tu_dev.units;
 t_stat r;
--- a/PDP10/pdp10_xtnd.c
+++ b/PDP10/pdp10_xtnd.c
@@ -138,9 +138,6 @@
 #define ED_SKPN         0600                            /* skip if N */
 #define ED_SKPA         0700                            /* skip always */

-extern d10 *ac_cur;                                     /* current AC block */
-extern const d10 bytemask[64];
-extern int32 flags;
 extern int32 rlog;
 extern jmp_buf save_env;