WAIT register save shouldn't save all registers like PX does +

need to restore interval timer when new process dispatched process level was incorrect when new process dispatched changes setting process abort flag in PCB when timer overflows
2026-04-03 03:43:19 +00:00 · 2005-09-19 00:00:00 -04:00
parent e20a46e164
commit 09b9592915
4 changed files with 101 additions and 84 deletions
--- a/em.c
+++ b/em.c
@@ -532,13 +532,12 @@ pa_t mapva(ea_t ea, short intacc, unsigned short *access, ea_t rp) {
 	pmaddr = ptaddr + 2*PAGENO(ea);
 	pte = mem[pmaddr];
 	ppn = mem[pmaddr+1];
-	if (T_MAP) fprintf(stderr,"        ptaddr=%o, pmaddr=%o, pte=%o\n", ptaddr, pmaddr, pte);
      } else {
 	pmaddr = ptaddr + PAGENO(ea);
 	pte = mem[pmaddr];
 	ppn = pte & 0xFFF;
-	if (T_MAP) fprintf(stderr,"        ptaddr=%o, pmaddr=%o, pte=%o\n", ptaddr, pmaddr, pte);
      }
+      if (T_MAP) fprintf(stderr,"        ptaddr=%o, pmaddr=%o, pte=%o\n", ptaddr, pmaddr, pte);
      if (!(pte & 0x8000))
 	fault(PAGEFAULT, 0, ea);
      mem[pmaddr] |= 040000;     /* set referenced bit */
@@ -582,8 +581,6 @@ pa_t mapva(ea_t ea, short intacc, unsigned short *access, ea_t rp) {
 #define put32(value, ea) (put32r((value),(ea),RP))
 #define put64(value, ea) (put64r((value),(ea),RP))

-/* Can V-mode do JMP# 4 to start executing from the register file?
-   Might need to "or" 0x80000000 with RPH to indicate this?? */ 

 unsigned short get16r(ea_t ea, ea_t rpring) {
  pa_t pa;
@@ -1881,7 +1878,7 @@ argt() {
 	if (ea & EXTMASK32)
 	  put16(bit<<12, stackfp+crs[Y]+2);
      }
-      if (T_PCL) fprintf(stderr," Stored\n");
+      if (T_PCL) fprintf(stderr," Stored arg IP at %o/%o\n\n", stackfp>>16, (stackfp+crs[Y]) & 0xFFFF);
      argsleft--;
      advancey = 1;
    }
@@ -1925,7 +1922,7 @@ pxregsave(unsigned short wait) {
  pcbp = *(unsigned int *)(crs+OWNER);
  regp = pcbp+PCBREGS;
  mask = 0;
-  for (i=(wait?12:0); i<16; i++) {
+  for (i=(wait?014:0); i<020; i++) {
    if (crsl[i] != 0) {
      mask |= bitmask16[i+1];
      put32r(crsl[i], regp, 0);
@@ -1933,7 +1930,8 @@ pxregsave(unsigned short wait) {
    }
  }
  put16r(mask, pcbp+PCBMASK, 0);
-  crs[KEYS] |= 1;
+  put32r(*(unsigned int *)(crs+TIMER), pcbp+PCBIT, 0);  /* save interval timer */
+  crs[KEYS] |= 1;                     /* set save done bit */
  put16r(crs[KEYS], pcbp+PCBKEYS, 0);
 }

@@ -1950,7 +1948,7 @@ pxregload (ea_t pcbp) {
  if (T_PX) fprintf(stderr,"pxregload loading registers for process %o/%o\n", pcbp>>16, pcbp&0xFFFF);
  regp = pcbp+PCBREGS;
  mask = get16r(pcbp+PCBMASK, 0);
-  for (i=0; i<16; i++) {
+  for (i=0; i<020; i++) {
    if (mask & bitmask16[i+1]) {
      crsl[i] = get32r(regp, 0);
      regp += 2;
@@ -1961,6 +1959,7 @@ pxregload (ea_t pcbp) {
  newkeys(get16r(pcbp+PCBKEYS, 0));
  *(unsigned int *)(crs+DTAR2) = get32r(pcbp+PCBDTAR2, 0);
  *(unsigned int *)(crs+DTAR3) = get32r(pcbp+PCBDTAR3, 0);
+  *(unsigned int *)(crs+TIMER) = get32r(pcbp+PCBIT, 0);
  crs[OWNERL] = pcbp & 0xFFFF;

  if (T_PX) fprintf(stderr,"pxregload: registers loaded, ownerl=%o, modals=%o\n", crs[OWNERL], crs[MODALS]);
@@ -2141,7 +2140,6 @@ dispatcher() {
    pxregload(pcbp);
  }

-  crs[TIMER] = get16r(pcbp+PCBIT, 0);
  RP = *(unsigned int *)(crs+PB);
  crs[PBL] = 0;
  crs[KEYS] &= ~3;                           /* erase "in dispatcher" and "save done" */
@@ -2152,6 +2150,7 @@ dispatcher() {
  utempa = get16r(pcbp+PCBABT, 0);
  if (utempa != 0) {
    if (T_PX) fprintf(stderr,"dispatch: abort flags for %o are %o\n", crs[OWNERL], utempa);
+    //printf("dispatch: abort flags for %o are %o\n", crs[OWNERL], utempa);
    put16r(0, pcbp+PCBABT, 0);
    fault(PROCESSFAULT, utempa, 0);
    fatal("fault returned after process fault");    
@@ -2271,14 +2270,14 @@ pwait() {
  short count;

  ea = apea(NULL);
-  if (T_PX) fprintf(stderr,"%o/%o: WAIT on %o/%o, pcb %o, keys=%o, modals=%o\n", RPH, RPL, ea>>16, ea&0xFFFF, crs[OWNERL], crs[KEYS], crs[MODALS]);
+  if (T_PX) fprintf(stderr,"%o/%o: wait on %o/%o, pcb %o, keys=%o, modals=%o\n", RPH, RPL, ea>>16, ea&0xFFFF, crs[OWNERL], crs[KEYS], crs[MODALS]);
  utempl = get32r(ea, 0);     /* get count and BOL */
  count = utempl>>16;         /* count (signed) */
  bol = utempl & 0xFFFF;      /* beginning of wait list */
  if (T_PX) fprintf(stderr," wait list count was %d, bol was %o\n", count, bol);
  count++;
  if (count > 0) {      /* I have to wait */
-#if 0
+#if 1
    if (count == 1 && bol != 0)
      fatal("WAIT: count == 1 but bol != 0");
 #else
@@ -2299,13 +2298,15 @@ keys = 14200, modals=137
      printf("WAIT: pcba=%o != ownerl=%o\n", regs.sym.pcba, crs[OWNERL]);
      fatal(NULL);
    }
-    mylev = get32r(*(ea_t *)(crs+OWNER),0);
+    mylev = get16r(*(ea_t *)(crs+OWNER),0);

    if (bol != 0) {
      pcbp = MAKEVA(crs[OWNERH],bol);
      pcblevnext = get32r(pcbp, 0);
      pcblev = pcblevnext >> 16;
    }
+    if (T_PX) fprintf(stderr," my level=%o, pcblev=%o\n", mylev, pcblev);
+
    if (count == 1 || mylev < pcblev) {   /* add me to the beginning */
      utempl = (count<<16) | crs[OWNERL];
      put32r(utempl, ea, 0);    /* update semaphore count/bol */
@@ -2322,6 +2323,7 @@ keys = 14200, modals=137
      }
      put16r(crs[OWNERL], prevpcbp+PCBLINK, 0);
      put16r(*(unsigned short *)&count, ea, 0);    /* update count */
+      if (T_PX) fprintf(stderr," new count=%d, new link for pcb %o=%o, bol=%o\n", prevpcbp&0xffff, crs[OWNERL], bol);
    }
    unready(ea, bol);
    dispatcher();
@@ -2343,6 +2345,7 @@ nfy(unsigned short inst) {
  ea_t ea, pcbp;
  unsigned int utempl;
  short scount;
+  static char *nfyname[] = {"nfye","nfyb"," "," ","inen","inbn","inec","inbc"};

  resched = 0;
  begend = inst & 1;
@@ -2356,7 +2359,7 @@ nfy(unsigned short inst) {
  utempl = get32r(ea, 0);     /* get count and BOL */
  scount = utempl>>16;        /* count (signed) */
  bol = utempl & 0xFFFF;      /* beginning of wait list */
-  if (T_PX) fprintf(stderr,"%o/%o: NFYB/E opcode %o, ea=%o/%o, count=%d, bol=%o, I am %o\n", RPH, RPL, inst, ea>>16, ea&0xFFFF, scount, bol, crs[OWNERL]);
+  if (T_PX) fprintf(stderr,"%o/%o: opcode %o %s, ea=%o/%o, count=%d, bol=%o, I am %o\n", RPH, RPL, inst, nfyname[inst-01200], ea>>16, ea&0xFFFF, scount, bol, crs[OWNERL]);
  if (scount > 0) {
    if (bol == 0) {
      printf("NFYB: bol is zero, count is %d for semaphore at %o/%o\n", scount, ea>>16, ea&0xFFFF);
@@ -2557,6 +2560,7 @@ main (int argc, char **argv) {
  float tempf,tempf1,tempf2;
  double tempd,tempd1,tempd2;
  unsigned short tempda[4],tempda1[4];
+  ea_t tempea;
  unsigned int ea32;                   /* full V/I mode eff address */
  ea_t ea;                             /* final MR effective address */
  ea_t earp;                           /* RP to use for eff address calcs */
@@ -2711,10 +2715,9 @@ main (int argc, char **argv) {

    for (i=0; i<9; i++)
      rvec[i] = readshort();
-    if (T_FLOW) fprintf(stderr,"SA=%o, EA=%o, P=%o, A=%o, B=%o, X=%o, K=%o\n\n", rvec[0], rvec[1],
-	    rvec[2], rvec[3], rvec[4], rvec[5], rvec[6]);
+    if (T_FLOW) fprintf(stderr,"SA=%o, EA=%o, P=%o, A=%o, B=%o, X=%o, K=%o\n\n", rvec[0], rvec[1], rvec[2], rvec[3], rvec[4], rvec[5], rvec[6]);
    if (rvec[2] > rvec[1])
-      fatal("Program start > EA: runfile is trashed");
+      fatal("Program start > ending: runfile is trashed");
  }

  /* read memory image from SA to EA inclusive */
@@ -2764,6 +2767,11 @@ main (int argc, char **argv) {
 #if 1
    if (traceflags != 0)
      savetraceflags = traceflags;
+#endif
+
+#if 0
+    if (traceflags != 0)
+      savetraceflags = traceflags;
    if (crs[OWNERL] == 0100100 && savetraceflags)
      traceflags = savetraceflags;
    else
@@ -2870,9 +2878,12 @@ main (int argc, char **argv) {
    earp = RP;

    if (crs[MODALS] & 010) {     /* px enabled, bump 1ms process timer */
-      if ((instcount & instpermsecmask) == 0) {
-
+      if (crs[TIMERL]++ > instpermsec) {
+	crs[TIMERL] = 0;
 #if 0
+	if (crs[OWNERL] == 0100100)
+	  printf("SUP timer=%d\n", *(short *)(crs+TIMER));
+
 	/* bump all timers, applying corrections based on actual time
 	   if necessary */

@@ -2882,11 +2893,12 @@ main (int argc, char **argv) {

 	/* if 1ms resolution process timer overflows, set pcb abort flag */

-	if (++crs[TIMER] == 0) {
-	  if (T_PX) printf("pcb %o timer overflow\n", crs[OWNERL]);
+	crs[TIMER]++;
+	if (crs[TIMER] == 0) {
+	  if (T_PX) fprintf(stderr, "#%d: pcb %o timer overflow\n", instcount, crs[OWNERL]);
 	  ea = *(ea_t *)(crs+OWNER);
-	  m = get16(ea+4) | 1;       /* set process abort flag */
-	  put16(m, ea+4);
+	  m = get16r(ea+4, 0) | 1;       /* set process abort flag */
+	  put16r(m, ea+4, 0);
 	}
      }
    }
@@ -2901,7 +2913,14 @@ main (int argc, char **argv) {
 #endif

 xec:
-    if (T_FLOW) fprintf(stderr,"\n			#%u [%s %o] SB: %o/%o LB: %o/%o %s XB: %o/%o\n%o/%o: %o		A='%o/%:0d B='%o/%d X=%o/%d Y=%o/%d C=%d L=%d LT=%d EQ=%d K=%o M=%o\n", instcount, searchloadmap(*(unsigned int *)(crs+OWNER),'x'), crs[OWNERL], crs[SBH], crs[SBL], crs[LBH], crs[LBL], searchloadmap(*(unsigned int *)(crs+LBH),'l'), crs[XBH], crs[XBL], RPH, RPL-1, inst, crs[A], *(short *)(crs+A), crs[B], *(short *)(crs+B), crs[X], *(short *)(crs+X), crs[Y], *(short *)(crs+Y), (crs[KEYS]&0100000) != 0, (crs[KEYS]&020000) != 0, (crs[KEYS]&0200) != 0, (crs[KEYS]&0100) != 0, crs[KEYS], crs[MODALS]);
+    /* NOTE: don't trace JMP * instructions (used to test PX) */
+
+    if (inst != 03777 && savetraceflags)
+      traceflags = savetraceflags;
+    else
+      traceflags = 0;
+
+    if (T_FLOW) fprintf(stderr,"\n			#%u [%s %o] IT=%d SB: %o/%o LB: %o/%o %s XB: %o/%o\n%o/%o: %o		A='%o/%:0d B='%o/%d X=%o/%d Y=%o/%d C=%d L=%d LT=%d EQ=%d K=%o M=%o\n", instcount, searchloadmap(*(unsigned int *)(crs+OWNER),'x'), crs[OWNERL], *(short *)(crs+TIMER), crs[SBH], crs[SBL], crs[LBH], crs[LBL], searchloadmap(*(unsigned int *)(crs+LBH),'l'), crs[XBH], crs[XBL], RPH, RPL-1, inst, crs[A], *(short *)(crs+A), crs[B], *(short *)(crs+B), crs[X], *(short *)(crs+X), crs[Y], *(short *)(crs+Y), (crs[KEYS]&0100000) != 0, (crs[KEYS]&020000) != 0, (crs[KEYS]&0200) != 0, (crs[KEYS]&0100) != 0, crs[KEYS], crs[MODALS]);

    /* begin instruction decode: generic? */

@@ -3283,6 +3302,7 @@ stfa:
 	      ZGETC(zea1, zlen1, zcp1, zclen1, zch1);
 	    } else
 	      zch1 = zspace;
+	    if (T_INST) fprintf(stderr," zch1=%o (%c)\n", zch1, zch1&0x7f);
 	    ZPUTC(zea2, zlen2, zcp2, zclen2, zch1);
 	  }
 	  crs[KEYS] |= 0100;
@@ -3304,6 +3324,7 @@ stfa:
 	  zclen2 = 0;
 	  while (zlen2) {
 	    ZGETC(zea1, zlen1, zcp1, zclen1, zch1);
+	    if (T_INST) fprintf(stderr," zch1=%o (%c)\n", zch1, zch1&0x7f);
 	    ZPUTC(zea2, zlen2, zcp2, zclen2, zch1);
 	  }
 	  crs[KEYS] |= 0100;
@@ -3321,10 +3342,10 @@ stfa:
 	  zea2 = crsl[FAR1];
 	  if (crsl[FLR1] & 0x8000)
 	    zea2 |= EXTMASK32;
-	  if (T_INST) fprintf(stderr," ea=%o/%o, len=%d\n", zea2>>16, zea2&0xffff, GETFLR(1));
+	  zch2 = crs[A];
+	  if (T_INST) fprintf(stderr," ea=%o/%o, len=%d, fill=%o (%c)\n", zea2>>16, zea2&0xffff, GETFLR(1), zch2, zch2&0x7f);
 	  //printf("ZFIL: ea=%o/%o, len=%d\n", zea2>>16, zea2&0xffff, GETFLR(1));
 	  zclen2 = 0;
-	  zch2 = crs[A];
 	  while (zlen2) {
 	    ZPUTC(zea2, zlen2, zcp2, zclen2, zch2);
 	    //printf(" after put, zlen2=%d, zcp2=%x, zclen2=%d, zch2=%o\n", zlen2, zcp2, zclen2, zch2);
@@ -3355,12 +3376,11 @@ stfa:
 	      ZGETC(zea1, zlen1, zcp1, zclen1, zch1);
 	    } else
 	      zch1 = zspace;
-	    if (T_INST) fprintf(stderr," zch1=%o\n", zch1);
 	    if (zlen2) {
 	      ZGETC(zea2, zlen2, zcp2, zclen2, zch2);
 	    } else
 	      zch2 = zspace;
-	    if (T_INST) fprintf(stderr," zch2=%o\n", zch2);
+	    if (T_INST) fprintf(stderr," zch1=%o (%c), zch2=%o (%c)\n", zch1, zch1&0x7f, zch2, zch2&0x7f);
 	    if (zch1 < zch2) {
 	      zresult = 0200;
 	      break;
@@ -3416,7 +3436,7 @@ stfa:
 	case 001215:
 	case 001216:
 	case 001217:
-	  if (T_FLOW) fprintf(stderr," NFY(%o)\n", inst);
+	  if (T_FLOW) fprintf(stderr," NFY\n", inst);
 	  RESTRICT();
 	  nfy(inst);
 	  continue;
@@ -3978,6 +3998,13 @@ bidy:
 		devpoll[i] -= utempl;
 	    usleep(utempl*1000/instpermsec);
 	    crs[X] = 0;
+	    utempa = crs[TIMER];
+	    crs[TIMER] += utempl/instpermsec;
+	    if (crs[TIMER] < utempa) {
+	      tempea = *(ea_t *)(crs+OWNER);
+	      utempa = get16r(tempea+4, 0) | 1;    /* set process abort flag */
+	      put16r(utempa, tempea+4, 0);
+	    }
 	    instcount += utempl;
 	  }
 	  if (crs[X] != 0)
@@ -6030,6 +6057,7 @@ svc() {
  short class;                     /* SVC class, from bits 5-10 */
  short func;                      /* SVC func within class, bits 11-16 */
  short temp16;
+  short dolocal;

  static struct {
    char name[8];                  /* svc routine name */
@@ -6215,7 +6243,16 @@ svc() {
      printf("Class %o, func %o: %s %d args %o\n", class,func, svcinfo[class][func].name, svcinfo[class][func].numargs, svcinfo[class][func].locargs);
 #endif

-  if (T_INST || T_FLOW) {
+  /* if location '65 is set, do indirect JST to handle svc */
+
+  /* if the svc fault vector is zero, interpret the svc here.  This
+     allows the emulator to run R-mode programs directly */
+
+  dolocal = 1;
+  if ((crs[MODALS] & 010) || get16(065) != 0)
+    dolocal = 0;
+
+  if (dolocal || T_INST || T_FLOW) {

    /* get svc code word, break into class and function */

@@ -6241,12 +6278,7 @@ svc() {
    if (T_FLOW) fprintf(stderr," name=%s, #args=%d, LOC args=%o\n", svcinfo[class][func].name, svcinfo[class][func].numargs, svcinfo[class][func].locargs);
  }

-  /* if location '65 is set, do indirect JST to handle svc */
-
-  /* if the svc fault vector is zero, interpret the svc here.  This
-     allows the emulator to run R-mode programs directly */
-
-  if ((crs[MODALS] & 010) || get16(065) != 0) {
+  if (!dolocal) {
    fault(SVCFAULT, 0, 0);
    fatal("Returned from SVC fault");
  }
--- a/emdev.h
+++ b/emdev.h
@@ -320,7 +320,7 @@ readasr:
 	if (T_INST) fprintf(stderr," character read=%o: %c\n", crs[A], crs[A] & 0x7f);
 	IOSKIP;
      } else  if (n != 0) {
-	printf("Unexpected error reading from tty, n=%d", n);
+	printf("Unexpected error reading from tty, n=%d\n", n);
 	fatal(NULL);
      }
    } else if (04 <= func && func <= 07) {  /* read control register 1/2 */
@@ -484,32 +484,13 @@ void devcp (short class, short func, short device) {
  static unsigned short clkvec;
  static short clkpic;

-#if 0
-  /* NOTE: setting this to 64,000 causes pointer faults when doing console
-     I/O during coldstart:
-OCP '1520
-C Pointer fault, ea_s=6, ea_w=42266, [ea]=100015
- Pointer fault, ea_s=6, ea_w=42266, [ea]=100015
-
-     Setting it to 300,000 causes:
-CUnimplemented INA device '26 function '06
-Fatal error: instruction #75661720 at 6/54305: 71404 101100
-keys = 14000, modals=137
-
-     Setting it to 600,000 works, but console output is very slow
-     Setting it to 200,000 causes undefined INA '0626
-     Setting it to 100,000 causes a hang after "Coldstarting PRIMOS..."
- */
-  #define SETCLKPOLL devpoll[device] = 600000;
-#else
-  #define SETCLKPOLL devpoll[device] = instpermsec*(-clkpic*3.2)/1000;
-#endif
+#define SETCLKPOLL devpoll[device] = instpermsec*(-clkpic*3.2)/1000;

  switch (class) {

  case 0:
    if (T_INST) fprintf(stderr," OCP '%02o%02o\n", func, device);
-    //printf("OCP '%02o%02o\n", func, device);
+    printf("OCP '%02o%02o\n", func, device);

    if (func == 0 || func == 015) {
      fprintf(stderr,"Clock process initialized!\n");
@@ -652,6 +633,7 @@ void devdisk (short class, short func, short device) {
  unsigned short dmareg, dmaaddr;
  unsigned short iobuf[4096];                /* local I/O buf, before mapped I/O */
  unsigned short *iobufp;
+  unsigned short access;
  short dmanw, dmanw1, dmanw2;
  unsigned int utempl;
  char ordertext[8];
@@ -803,18 +785,19 @@ void devdisk (short class, short func, short device) {
 	    dmaaddr = regs.sym.regdmx[dmareg+1];
 	    if (T_INST || T_DIO) fprintf(stderr, " DMA channels: nch-1=%d, ['%o]='%o, ['%o]='%o, nwords=%d\n", dc[device].dmanch, dc[device].dmachan, regs.sym.regdmx[dmareg], dc[device].dmachan+1, dmaaddr, dmanw);
 	    
-	    /* later, use mapva to do page-based mapped I/O in pieces */
-
 	    if (order == 5) {
 	      if (crs[MODALS] & 020)
-		iobufp = iobuf;
+		if ((dmaaddr & 01777) || dmanw > 1024)
+		  iobufp = iobuf;
+		else
+		  iobufp = mem+mapva(dmaaddr, WACC, &access, 0);
 	      else
 		iobufp = mem+dmaaddr;
 	      if (read(dc[device].unit[u].devfd, (char *)iobufp, dmanw*2) != dmanw*2) {
 		perror("Unable to read drive file");
 		fatal(NULL);
 	      }
-	      if (crs[MODALS] & 020)
+	      if (iobufp == iobuf)
 		for (i=0; i<dmanw; i++)
 		  put16r(iobuf[i], dmaaddr+i, 0);
 	    } else {
@@ -837,6 +820,11 @@ void devdisk (short class, short func, short device) {
 	}
 	break;

+	/* NOTE: for seek command, the track should probably be stored
+	   in a state variable, then checked for equality on
+	   read/write.  If not equal, a disk fault should occur rather
+	   than reading/writing from the wrong cylinder. */
+
      case 3: /* SSEEK = Seek */
 	track = m1 & 01777;
 	if (T_INST || T_DIO) fprintf(stderr," seek track %d, restore=%d, clear=%d\n", track, (m1 & 0100000) != 0, (m1 & 040000) != 0);
@@ -857,12 +845,19 @@ void devdisk (short class, short func, short device) {

      case 7: /* DSTALL = Stall */
 	if (T_INST || T_DIO) fprintf(stderr," stall\n");
-#if 0
+
+	/* NOTE: technically, the stall command is supposed to wait
+	   210 usecs, so that the disk controller doesn't hog the I/O
+	   bus by looping in a channel program waiting for I/O to
+	   complete.  With the emulator, this delay isn't necessary,
+	   although it will cause DIAG tests to fail if the delay is
+	   omitted.  Hence the PX test.  Ignoring stall gives a 25%
+	   increase in I/O's per second on a 2GHz Mac (8MB emulator). */
+
+	if (crs[MODALS] & 010)             /* PX enabled? */
+	  break;                           /* yes, no stall */
 	devpoll[device] = instpermsec/5;   /* 200 microseconds, sb 210 */
 	return;
-#else
-	break;
-#endif

      case 9: /* DSTAT = Store status to memory */
 	if (T_INST || T_DIO) fprintf(stderr, " store status='%o to '%o\n", dc[device].status, m1);
@@ -878,24 +873,6 @@ void devdisk (short class, short func, short device) {
 	dc[device].dmanch = m & 017;
 	dc[device].dmachan = m1;
 	if (T_INST || T_DIO) fprintf(stderr, " set DMA channels, nch-1=%d, channel='%o\n", dc[device].dmanch, dc[device].dmachan);
-#if 0
-	dmareg = ((m1 & 036) << 1) | (m1 & 1);
-	//for (i=0; i<4; i++)
-	//fprintf(stderr, " dmareg+%d = %o  ", i, regs.sym.regdmx[dmareg+i]);
-	//fprintf(stderr, "\n");
-
-	dmanw1 = regs.sym.regdmx[dmareg];
-	dmanw1 = -(dmanw1>>4);
-	dmanw2 = regs.sym.regdmx[dmareg+4];
-	dmanw2 = -(dmanw2>>4);
-	if (T_INST || T_DIO) fprintf(stderr, " dmareg=%d, nch=%d, dmanw1=%d, dmanw2=%d\n", dmareg, dc[device].dmanch, dmanw1, dmanw2);
-	if (dc[device].dmanch == 1 && dmanw1 == 1024 && dmanw2 == 16) {
-	  if (T_INST || T_DIO) fprintf(stderr, " swapped DMA channels!\n");
-	  utempl = *(int *)(regs.sym.regdmx+dmareg);
-	  *(int *)(regs.sym.regdmx+dmareg) = *(int *)(regs.sym.regdmx+dmareg+4);
-	  *(int *)(regs.sym.regdmx+dmareg+4) = utempl;
-	}
-#endif
 	break;

      case 14: /* DINT = generate interrupt through vector address */
--- a/os.c
+++ b/os.c
@@ -33,7 +33,11 @@ os_c1in(short *charg) {
  int n;

  fprintf(stderr," c1in waiting for data\n");
-  n = read(os.ttydev, &ch, 1);
+  do {
+    n = read(os.ttydev, &ch, 1);
+    if (n == 0)
+      sleep(1);
+  } while (n == 0);
  if (n < 0) {
    perror(" error reading from tty");
    exit(1);
@@ -42,6 +46,8 @@ os_c1in(short *charg) {
    fprintf(stderr," unexpected error reading from tty, n=%d", n);
    exit(1);
  }
+  if (ch == 015)
+    ch = 012;
  *charg = ch | 0x80;
 }

--- a/regs.h
+++ b/regs.h
@@ -52,6 +52,8 @@
 #define FCODE 44
 #define FADDR 46
 #define TIMER 48
+#define TIMERH 48
+#define TIMERL 49

 /* these are 32-bit offsets into crsl (current register set long) */