diff --git a/vimlac/Makefile b/vimlac/Makefile
index 7cc91a6..61fceaa 100755
--- a/vimlac/Makefile
+++ b/vimlac/Makefile
@@ -1,16 +1,16 @@
 DEVFILES = cpu.o dcpu.o ptrptp.o memory.o kb.o ttyin.o ttyout.o trace.o error.o log.o plist.o bootstrap.o
+HFILES = cpu.h dcpu.h ptrptp.h memory.h kb.h ttyin.h ttyout.h trace.h error.h log.h plist.h bootstrap.h
 OFILES = vimlac.o $(DEVFILES)
 
-#CFLAGS=-fPIC -O2 -Wall -ansi -pedantic -std=c99 -g
 CFLAGS=-O2 -Wall -ansi -pedantic -std=c99 -g
 
-test_cpu:	test_cpu.c $(DEVFILES) Makefile
-	gcc -o test_cpu ${CFLAGS} $(DEVFILES) test_cpu.c
-
 test:	test_cpu
 	rm -f vimlac.log
 	./test_cpu CPU.test
 
+test_cpu:	test_cpu.c $(DEVFILES) Makefile
+	gcc -o test_cpu ${CFLAGS} $(DEVFILES) test_cpu.c
+
 vimlac:	${OFILES} Makefile
 	gcc -o vimlac ${CFLAGS} ${OFILES}
 
diff --git a/vimlac/error.c b/vimlac/error.c
index 2669f99..341cea6 100644
--- a/vimlac/error.c
+++ b/vimlac/error.c
@@ -21,7 +21,7 @@ error(char *fmt, ...)
 
     va_start(ap, fmt);
     vsprintf(buff, fmt, ap);
-    fprintf(stderr, "%s\n", buff);
+    fprintf(stderr, "\n%s\n", buff);
     va_end(ap);
 
     exit(10);
diff --git a/vimlac/ptrptp.c b/vimlac/ptrptp.c
index af981f8..1699a5f 100755
--- a/vimlac/ptrptp.c
+++ b/vimlac/ptrptp.c
@@ -35,8 +35,6 @@
 #define InUsePTR "PTR"
 #define InUsePTP "PTP"
 
-#define STREQ(a, b) (strcmp((a), (b)) == 0)
-
 
 /*****
  * State variables for the general device
@@ -57,10 +55,21 @@ static bool ptr_at_eof = true;
 static BYTE ptr_value = PTR_EOF;
 
 
+void ptrptp_reset(void)
+{
+    device_ready = false;
+    device_use = NULL;
+    device_motor_on = false;
+    device_open_file = NULL;
+    device_filename = NULL;
+    device_cycle_count = 0;
+}
+
+
 int
 ptr_mount(char *fname)
 {
-    if (device_use && STREQ(device_use, InUsePTP))
+    if (STREQ(device_use, InUsePTP))
        error("ptr_mount: Can't mount PTR file, being used as PTP");
 
     device_filename = fname;
@@ -75,6 +84,7 @@ ptr_mount(char *fname)
     ptr_at_eof = false;
     ptr_value = PTR_EOF;
     device_cycle_count = PTR_NOT_PTR_READY_CYCLES;
+    device_use = InUsePTR;
 
     return 0;
 }
@@ -83,7 +93,7 @@ ptr_mount(char *fname)
 void
 ptr_dismount(void)
 {
-    if (device_use && STREQ(device_use, InUsePTP))
+    if (STREQ(device_use, InUsePTP))
        error("ptr_mount: Can't dismount PTR file, being used as PTP");
 
     if (device_open_file)
@@ -94,14 +104,15 @@ ptr_dismount(void)
     device_ready = false;
     ptr_at_eof = true;
     ptr_value = PTR_EOF;
+    device_use = NULL;
 }
 
 
 void
 ptr_start(void)
 {
-    if (device_use && STREQ(device_use, InUsePTP))
-       error("ptrptp_start: Can't start PTR motor, being used as PTP");
+    if (STREQ(device_use, InUsePTP))
+       error("ptrptp_start: Can't start PTR motor, being used as PTP, device_use=%s", device_use);
 
     device_motor_on = true;
     device_ready = false;
@@ -112,7 +123,7 @@ ptr_start(void)
 void
 ptr_stop(void)
 {
-    if (device_use && STREQ(device_use, InUsePTP))
+    if (STREQ(device_use, InUsePTP))
        error("ptr_stop: Can't stop PTR motor, being used as PTP");
 
     device_motor_on = false;
@@ -124,7 +135,7 @@ ptr_stop(void)
 int
 ptr_read(void)
 {
-    if (device_use && STREQ(device_use, InUsePTP))
+    if (STREQ(device_use, InUsePTP))
         error("ptr_read: Can't read PTR, device being used as PTP");
 
     return ptr_value;
@@ -134,7 +145,6 @@ ptr_read(void)
 bool
 ptr_ready(void)
 {
-    vlog("ptr_ready: returning %s (%d)", (device_ready) ? "true" : "false", device_ready);
     return device_ready;
 }
 
@@ -142,9 +152,8 @@ ptr_ready(void)
 void
 ptr_tick(long cycles)
 {
-    vlog("ptr_tick: (1) device_ready=%s (%d)", (device_ready) ? "true" : "false", device_ready);
     // if not being used as PTR, do nothing
-    if (device_use && !STREQ(device_use, InUsePTR))
+    if (STREQ(device_use, InUsePTP))
         return;
 
     /* if no state change */
@@ -155,27 +164,21 @@ ptr_tick(long cycles)
     device_cycle_count -= cycles;
     if (device_cycle_count <= 0L)
     {
-        vlog("ptr_tick: **** device_ready=%s (%d)", (device_ready) ? "true" : "false", device_ready);
         if (device_ready == true)
         {
             device_ready = false;
             device_cycle_count += PTR_NOT_PTR_READY_CYCLES;
-	    ptr_value = 0;
         }
         else
         {
             device_ready = true;
             device_cycle_count += PTR_READY_CYCLES;
             if (fread(&ptr_value, sizeof(BYTE), 1, device_open_file) != 1)
-            {   /* assume EOF on file, dismount tape */
-//		fclose(device_open_file);
-//		device_open_file = NULL;
+            {   /* EOF on file */
                 ptr_at_eof = true;
                 ptr_value = PTR_EOF;
             }
         }
-        vlog("ptr_tick: device_cycle_count=%d, device_ready->%s (%d)",
-                device_cycle_count, (device_ready) ? "true" : "false", device_ready);
     }
 }
 
@@ -184,8 +187,8 @@ ptr_tick(long cycles)
 int
 ptp_mount(char *fname)
 {
-    if (device_use && STREQ(device_use, InUsePTR))
-        error("ptp_mount: Can't mount PTP, device being used as PTR");
+    if (STREQ(device_use, InUsePTR))
+        error("ptp_mount: Can't mount PTP, device being used as '%s'", device_use);
 
     device_use = InUsePTP;
     device_filename = fname;
@@ -206,7 +209,7 @@ ptp_mount(char *fname)
 void
 ptp_dismount(void)
 {
-    if (device_use && STREQ(device_use, InUsePTR))
+    if (STREQ(device_use, InUsePTR))
        error("ptp_dismount: Can't dismount PTP, device being used as PTR");
 
     if (device_open_file)
@@ -221,6 +224,9 @@ ptp_dismount(void)
 void
 ptp_start(void)
 {
+    if (STREQ(device_use, InUsePTR))
+       error("ptp_dismount: Can't start PTP, device being used as PTR");
+
     device_motor_on = true;
     device_ready = false;
     device_cycle_count = PTP_NOT_READY_CYCLES;
@@ -230,6 +236,9 @@ ptp_start(void)
 void
 ptp_stop(void)
 {
+    if (STREQ(device_use, InUsePTR))
+       error("ptp_stop: Can't stop PTP, device being used as PTR");
+
     device_motor_on = false;
     device_cycle_count = PTP_NOT_READY_CYCLES;
 }
@@ -238,6 +247,9 @@ ptp_stop(void)
 void
 ptp_punch(BYTE value)
 {
+    if (STREQ(device_use, InUsePTR))
+       error("ptp_punch: Can't punch PTP, device being used as PTR");
+
     if (device_motor_on && device_open_file != NULL)
     {
         putc(value, device_open_file);
@@ -256,11 +268,14 @@ ptp_ready(void)
 void
 ptp_tick(long cycles)
 {
-    /* if no state change */
-    if (!device_motor_on || device_open_file == NULL)
+    if (STREQ(device_use, InUsePTR))
+       return;
+
+    /* if no mounted file */
+    if (device_open_file == NULL)
         return;
 
-    /* tape in, motor on */
+    /* tape in */
     device_cycle_count -= cycles;
     if (device_cycle_count <= 0L)
     {
diff --git a/vimlac/ptrptp.h b/vimlac/ptrptp.h
index 35c7deb..8c7ac31 100755
--- a/vimlac/ptrptp.h
+++ b/vimlac/ptrptp.h
@@ -5,6 +5,7 @@
 #ifndef PTRPTP_H
 #define PTRPTP_H
 
+void ptrptp_reset(void);
 int ptr_mount(char *fname);
 void ptr_dismount(void);
 void ptr_start(void);
diff --git a/vimlac/test_cpu.c b/vimlac/test_cpu.c
index b1c0df5..71cb16f 100644
--- a/vimlac/test_cpu.c
+++ b/vimlac/test_cpu.c
@@ -25,9 +25,6 @@
 #include "trace.h"
 
 
-// string comparison macro
-#define STREQ(a, b) (strcmp((a), (b)) == 0)
-
 // constants
 const char *LstFilename = "_#TEST#_.lst";   // LST filename
 const char *AsmFilename = "_#TEST#_.asm";   // ASM filename
@@ -705,6 +702,59 @@ mount(char *device, char *filename)
 }
 
 
+/******************************************************************************
+Description : Dismount a file on a device.
+ Parameters : device  - a device name ("PTR", "PTP", "TTYIN" or "TTYOUT")
+            : ignore  - unused
+    Returns : The number of errors encountered (0 or 1).
+   Comments : 
+ ******************************************************************************/
+int
+dismount(char *device, char *ignore)
+{
+//    strupper(device);
+
+    if (STREQ(device, "PTR"))
+        ptr_dismount();
+    else if (STREQ(device, "PTP"))
+        ptp_dismount();
+    else
+    {
+        vlog("dismount: device name not recognized: %s", device);
+        return 1;
+    }
+
+    return 0;
+}
+
+
+/******************************************************************************
+Description : Checkk that two files are identical.
+ Parameters : file1, file2 - files to check
+    Returns : The number of errors encountered (0 or 1).
+   Comments : 
+ ******************************************************************************/
+int
+checkfile(char *file1, char *file2)
+{
+    char buffer[1024];
+
+    strlower(file1);
+    strlower(file2);
+
+    // assemble the file
+    sprintf(buffer, "cmp %s %s >/dev/null 2>&1", file1, file2);
+    printf("%s\n", buffer);
+    if (system(buffer) == -1)
+    {
+        vlog("checkfile: files '%s' and '%s' differ", file1, file2);
+        return 1;
+    }
+
+    return 0;
+}
+
+
 /******************************************************************************
 Description : Check that a memory address contents is as expected.
  Parameters : address - memory address to check (string)
@@ -862,20 +912,16 @@ assemble(WORD addr, char *opcodes)
     char *new_strcopy;
     int  num_opcodes = 0;
 
-    vlog("assemble: addr=%07o, opcodes=%s", addr, opcodes);
-
     // create the ASM file
     fd = fopen(AsmFilename, "wb");
     fprintf(fd, "\torg\t%07o\n", addr);
     while ((new_strcopy = split(strcopy, '|')))
     {
-        vlog("assemble: code=%s", strcopy);
         fprintf(fd, "\t%s\n", strcopy);
         ++num_opcodes;
         strcopy = new_strcopy;
     }
     // handle last opcode
-    vlog("assemble: code=%s", strcopy);
     fprintf(fd, "\t%s\n", strcopy);
     ++num_opcodes;
 
@@ -883,8 +929,6 @@ assemble(WORD addr, char *opcodes)
     fclose(fd);
     free(old_strcopy);
 
-    vlog("assemble: num_opcodes=%d", num_opcodes);
-
     // assemble the file
     sprintf(buffer, "../iasm/iasm -l %s %s", LstFilename, AsmFilename);
     if (system(buffer) == -1)
@@ -910,7 +954,6 @@ assemble(WORD addr, char *opcodes)
         // read first word value
         if (sscanf(buffer, "%o", &new_opcode->opcode) != 1)
             error("Badly formatted assembler output: %s", buffer);
-        vlog("assemble: assembly output: %07o", new_opcode->opcode);
 
         // add binary opcode to end of result list
         if (result == NULL)
@@ -1016,7 +1059,6 @@ parse_one_cmd(char *scan)
                     v = v->next;
                 }
                 field2 = tmpbuff+1;
-                vlog("parse_one_cmd: field2=%s", field2);
             }
             else
             {
@@ -1314,6 +1356,8 @@ run_one_test(Test *test)
 
     UsedCycles = 0;
 
+    ptrptp_reset();
+
     trace_open();
 
     for (Command *cmd = test->commands; cmd; cmd = cmd->next)
@@ -1357,6 +1401,10 @@ run_one_test(Test *test)
             error += checkcpu(fld1, fld2);
         else if (STREQ(opcode, "MOUNT"))
             error += mount(fld1, fld2);
+        else if (STREQ(opcode, "DISMOUNT"))
+            error += dismount(fld1, fld2);
+        else if (STREQ(opcode, "CHECKFILE"))
+            error += checkfile(fld1, fld2);
         else
         {
             printf("Unrecognized operation '%s' at line %d\n",
@@ -1433,7 +1481,7 @@ run_tests(Test *test)
         test = test->next;
     }
 
-    printf("\r");
+    printf("\n");
     fflush(stdout);
 
     return errors;
diff --git a/vimlac/vimlac.h b/vimlac/vimlac.h
index 4c4174a..84b610c 100755
--- a/vimlac/vimlac.h
+++ b/vimlac/vimlac.h
@@ -12,6 +12,9 @@
 #include <string.h>
 #include <errno.h>
 
+#include "error.h"
+
+
 typedef unsigned int	WORD;
 typedef unsigned char	BYTE;
 
@@ -22,7 +25,11 @@ typedef unsigned char	BYTE;
 #define OVERFLOWMASK	0x10000
 #define LOWBITMASK	0x1
 
+// macro to convert a boolean value to a string
+#define BOOL2STR(a)     ((a) ? "true" : "false")
+
+// macro to more reliably compare strings
+#define STREQ(a, b) ((a) && (strcmp((a), (b)) == 0))
 
-void error(char *msg, ...);
 
 #endif