diff --git a/cpuinstr/add.c b/cpuinstr/add.c
index 71041f4..6a64f5f 100644
--- a/cpuinstr/add.c
+++ b/cpuinstr/add.c
@@ -99,7 +99,7 @@ static void add(struct cpu *cpu, WORD op)
     }
 
     if(op & 0x100) {
-      ea_begin_modify(cpu, op, r, 0, long_ops(op), 0, 0);
+      ea_begin_modify_ugly(cpu, op, r, 0, long_ops(op), 0, 0);
       cpu_set_flags_add(cpu, cpu->d[reg]&m, operand&m, r&m, r);
     } else {
       cpu_set_flags_add(cpu, operand&m, cpu->d[reg]&m, r&m, r);
diff --git a/cpuinstr/clr.c b/cpuinstr/clr.c
index afe393d..91b9bb6 100644
--- a/cpuinstr/clr.c
+++ b/cpuinstr/clr.c
@@ -2,10 +2,7 @@
 #include "cpu.h"
 #include "cprint.h"
 #include "ea.h"
-
-#define CLR_READ      1
-#define CLR_PREFETCH  2
-#define CLR_WRITE     3
+#include "ucode.h"
 
 /*
  * --------------------------------------------------------------------
@@ -32,41 +29,33 @@
  *     (xxx).W       | 12(1/2) 12(3/0) |      np nR nr | np nw nW
  *     (xxx).L       | 12(1/2) 16(4/0) |   np np nR nr | np nw nW
  */
-static void clr(struct cpu *cpu, WORD op)
+
+static void clr_compute(struct cpu *cpu, WORD op)
 {
-  LONG operand;
-  ENTER;
+  ea_set_data(0);
+  cpu_set_flags_clr(cpu);
 
-  switch(cpu->instr_state) {
-  case INSTR_STATE_NONE:
-    ea_begin_read(cpu, op);
-    cpu->instr_state = CLR_READ;
-    // Fall through.
-  case CLR_READ:
-    if(!ea_done(&operand)) {
-      ADD_CYCLE(2);
-      break;
-    } else {
-      cpu->instr_state = CLR_PREFETCH;
-    }
-    // Fall through.
-  case CLR_PREFETCH:
-    ADD_CYCLE(4);
-    cpu_prefetch();
-    cpu->instr_state = CLR_WRITE;
-    ea_begin_modify(cpu, op, 0, 0, 2, 0, 0);
-    break;
-  case CLR_WRITE:
-    if(ea_done(&operand)) {
-      cpu->instr_state = INSTR_STATE_FINISHED;
-    } else {
-      ADD_CYCLE(2);
-    }
-    cpu_set_flags_clr(cpu);
-    break;
+  if((op & 0xc38) == 0x800) {
+    ujump(nop_uops, 1);
+  } else {
+    ujump(0, 0);
   }
 }
 
+static u_sequence clr_seq[] =
+{
+  ea_begin_read,
+  u_prefetch,
+  clr_compute,
+  ea_begin_modify,
+  u_end_sequence
+};
+
+static void clr(struct cpu *cpu, WORD op)
+{
+  u_start_sequence(clr_seq, cpu, op);
+}
+
 static struct cprint *clr_print(LONG addr, WORD op)
 {
   struct cprint *ret;
diff --git a/cpuinstr/ea.c b/cpuinstr/ea.c
index 870dff1..177df14 100644
--- a/cpuinstr/ea.c
+++ b/cpuinstr/ea.c
@@ -247,13 +247,18 @@ void ea_begin_read(struct cpu *cpu, WORD op)
   }
 }
 
+void ea_begin_modify(struct cpu *cpu, WORD op)
+{
+  ea_begin_modify_ugly(cpu, op, ea_data, 0, 0, 0, 0);
+}
+
 static uop_t write_reg_uops[] = { n, n, n };
 static uop_t write_mem_uops[] = { w, n, w, n };
 
 // dw, dl, aw, al are the number of additional microcycles needed to
 // write a data or address register with a word or a long.
-void ea_begin_modify(struct cpu *cpu, WORD op, LONG data,
-		     int dw, int dl, int aw, int al)
+void ea_begin_modify_ugly(struct cpu *cpu, WORD op, LONG data,
+			  int dw, int dl, int aw, int al)
 {
   //						Byte/Word	Long
   //						Dn, An, Mem	Dn, An, Mem
@@ -339,6 +344,11 @@ int ea_done(LONG *operand)
   return 0;
 }
 
+void ea_set_data(LONG data)
+{
+  ea_data = data;
+}
+
 LONG ea_get_address(void)
 {
   return ea_address;
diff --git a/cpuinstr/ea.h b/cpuinstr/ea.h
index 5dd57ac..cd8eabc 100644
--- a/cpuinstr/ea.h
+++ b/cpuinstr/ea.h
@@ -121,8 +121,11 @@ void ea_clear_prefetch_before_write();
 void ea_begin_address(struct cpu *cpu, WORD op);
 void ea_begin_read(struct cpu *cpu, WORD op);
 void ea_begin_write(struct cpu *cpu, WORD op);
-void ea_begin_modify(struct cpu *cpu, WORD op, LONG data, int, int, int, int);
+void ea_begin_modify(struct cpu *cpu, WORD op);
 int ea_done(LONG *);
+void ea_begin_modify_ugly(struct cpu *cpu, WORD op, LONG data, int, int, int, int);
+int ea_done(LONG *);
+void ea_set_data(LONG data);
 LONG ea_get_address(void);
 
 #endif
diff --git a/cpuinstr/exg.c b/cpuinstr/exg.c
index 110f0c2..2b90c54 100644
--- a/cpuinstr/exg.c
+++ b/cpuinstr/exg.c
@@ -1,8 +1,7 @@
 #include "common.h"
 #include "cpu.h"
 #include "cprint.h"
-
-#define EXG_IN_PROGRESS 1
+#include "ucode.h"
 
 /*
  * --------------------------------------------------------------------
@@ -14,43 +13,44 @@
  *     Ax,Ay         |  6(1/0)         |  np       n
  *     Dx,Ay         |  6(1/0)         |  np       n
  */
-static void exg(struct cpu *cpu, WORD op)
+static void exg_compute(struct cpu *cpu, WORD op)
 {
+  int rx, ry;
   LONG t;
-  int rx,ry;
-
-  ENTER;
 
-  switch(cpu->instr_state) {
-  case INSTR_STATE_NONE:
-    ADD_CYCLE(4);
-    cpu->instr_state = EXG_IN_PROGRESS;
-    cpu_prefetch();
+  rx = (op&0xe00)>>9;
+  ry = (op&7);
+  switch(op&0xf8) {
+  case 0x40: /* Dx,Dy */
+    t = cpu->d[rx];
+    cpu->d[rx] = cpu->d[ry];
+    cpu->d[ry] = t;
     break;
-  case EXG_IN_PROGRESS:
-    rx = (op&0xe00)>>9;
-    ry = (op&7);
-    switch(op&0xf8) {
-    case 0x40: /* Dx,Dy */
-      t = cpu->d[rx];
-      cpu->d[rx] = cpu->d[ry];
-      cpu->d[ry] = t;
-      break;
-    case 0x48:/* Ax,Ay */
-      t = cpu->a[rx];
-      cpu->a[rx] = cpu->a[ry];
-      cpu->a[ry] = t;
-      break;
-    case 0x88:/* Dx,Ay */
-      t = cpu->d[rx];
-      cpu->d[rx] = cpu->a[ry];
-      cpu->a[ry] = t;
-      break;
-    }
-    ADD_CYCLE(2);
-    cpu->instr_state = INSTR_STATE_FINISHED;
+  case 0x48:/* Ax,Ay */
+    t = cpu->a[rx];
+    cpu->a[rx] = cpu->a[ry];
+    cpu->a[ry] = t;
+    break;
+  case 0x88:/* Dx,Ay */
+    t = cpu->d[rx];
+    cpu->d[rx] = cpu->a[ry];
+    cpu->a[ry] = t;
     break;
   }
+
+  ujump(nop_uops, 1);
+}
+
+static u_sequence exg_seq[] =
+{
+  u_prefetch,
+  exg_compute,
+  u_end_sequence
+};
+
+static void exg(struct cpu *cpu, WORD op)
+{
+  u_start_sequence(exg_seq, cpu, op);
 }
 
 static struct cprint *exg_print(LONG addr, WORD op)
diff --git a/cpuinstr/neg.c b/cpuinstr/neg.c
index 424a930..ee134ad 100644
--- a/cpuinstr/neg.c
+++ b/cpuinstr/neg.c
@@ -55,7 +55,7 @@ static void neg(struct cpu *cpu, WORD op)
     cpu_prefetch();
     cpu->instr_state = NEG_WRITE;
     r = -operand;
-    ea_begin_modify(cpu, op, r, 0, 2, 0, 0);
+    ea_begin_modify_ugly(cpu, op, r, 0, 2, 0, 0);
 
     switch((op&0xc0)>>6) {
     case 0: m = 0x80; r &= 0xff; break;
diff --git a/cpuinstr/negx.c b/cpuinstr/negx.c
index 19bb2db..664e04e 100644
--- a/cpuinstr/negx.c
+++ b/cpuinstr/negx.c
@@ -58,7 +58,7 @@ static void negx(struct cpu *cpu, WORD op)
     if(CHKX) {
       r--;
     }
-    ea_begin_modify(cpu, op, r, 0, 2, 0, 0);
+    ea_begin_modify_ugly(cpu, op, r, 0, 2, 0, 0);
 
     switch((op&0xc0)>>6) {
     case 0: m = 0x80; r &= 0xff; break;
diff --git a/cpuinstr/not.c b/cpuinstr/not.c
index 2478151..2d98190 100644
--- a/cpuinstr/not.c
+++ b/cpuinstr/not.c
@@ -34,7 +34,7 @@
  */
 static void not(struct cpu *cpu, WORD op)
 {
-  LONG operand, r, m = 0;
+  LONG operand, m = 0;
   ENTER;
 
   switch(cpu->instr_state) {
@@ -54,11 +54,11 @@ static void not(struct cpu *cpu, WORD op)
     ADD_CYCLE(4);
     cpu_prefetch();
     cpu->instr_state = NOT_WRITE;
-    ea_begin_modify(cpu, op, ~operand, 0, 2, 0, 0);
+    ea_begin_modify_ugly(cpu, op, ~operand, 0, 2, 0, 0);
 
     switch((op&0xc0)>>6) {
-    case 0: m = 0x80; r &= 0xff; break;
-    case 1: m = 0x8000; r &= 0xffff; break;
+    case 0: m = 0x80; break;
+    case 1: m = 0x8000; break;
     case 2: m = 0x80000000; break;
     }
     cpu_set_flags_move(cpu, operand & m, operand);
diff --git a/cpuinstr/sub.c b/cpuinstr/sub.c
index 21e8f8f..97f0949 100644
--- a/cpuinstr/sub.c
+++ b/cpuinstr/sub.c
@@ -99,7 +99,7 @@ static void sub(struct cpu *cpu, WORD op)
 
     if(op & 0x100) {
       r = operand - cpu->d[reg];
-      ea_begin_modify(cpu, op, r, 0, long_ops(op), 0, 0);
+      ea_begin_modify_ugly(cpu, op, r, 0, long_ops(op), 0, 0);
       cpu_set_flags_sub(cpu, cpu->d[reg]&m1, operand&m1, r&m1, r&m2);
     } else {
       r = cpu->d[reg] - operand;
diff --git a/cpuinstr/ucode.c b/cpuinstr/ucode.c
index 6a6e94f..e333b40 100644
--- a/cpuinstr/ucode.c
+++ b/cpuinstr/ucode.c
@@ -1,5 +1,10 @@
+#include "common.h"
 #include "ucode.h"
 
+#define INSTR_STATE_RUNNING 1
+
+static u_sequence *seq_pointer;
+
 static int ucycles;
 static uop_t *upc;
 
@@ -20,3 +25,46 @@ int ustep(void)
   
   return 0;
 }
+
+void u_start_sequence(u_sequence *seq, struct cpu *cpu, WORD op)
+{
+  if(cpu->instr_state == INSTR_STATE_NONE) {
+    cpu->instr_state = INSTR_STATE_RUNNING;
+    seq_pointer = seq;
+    ujump(0, 0);
+  }
+
+  while(ustep()) {
+    (*seq_pointer)(cpu, op);
+    seq_pointer++;
+    if(cpu->instr_state == INSTR_STATE_FINISHED)
+      break;
+    else
+      ADD_CYCLE(2);
+  }    
+}
+
+void u_end_sequence(struct cpu *cpu, WORD op)
+{
+  cpu->instr_state = INSTR_STATE_FINISHED;
+  ujump(0, 0);
+}
+
+// Do nothing.
+static void u_nop(void)
+{
+}
+
+// Fetch from program.
+static void u_pf(void)
+{
+  cpu_prefetch();
+}
+
+uop_t nop_uops[] = { u_nop, u_nop };
+static uop_t prefetch_uops[] = { u_pf, u_nop };
+
+void u_prefetch(struct cpu *cpu, WORD op)
+{
+  ujump(prefetch_uops, 2);
+}
diff --git a/cpuinstr/ucode.h b/cpuinstr/ucode.h
index 65eed9d..acac00d 100644
--- a/cpuinstr/ucode.h
+++ b/cpuinstr/ucode.h
@@ -1,8 +1,15 @@
 #ifndef UCODE_H
 #define UCODE_H
 
+typedef void (*u_sequence)(struct cpu *cpu, WORD op);
+extern void u_start_sequence(u_sequence *, struct cpu *, WORD);
+extern void u_end_sequence(struct cpu *, WORD);
+extern void u_prefetch(struct cpu *, WORD);
+
 typedef void (*uop_t)(void);
 extern void ujump(uop_t *, int);
 extern int ustep(void);
 
+extern uop_t nop_uops[];
+
 #endif /* UCODE_H */