diff --git a/dsim.c b/dsim.c
index 883a0ee..1876279 100644
--- a/dsim.c
+++ b/dsim.c
@@ -8,6 +8,9 @@
 #include <fcntl.h>
 #include <unistd.h>
 
+#define EMU_ID 0xed6f
+#define EMU_VER 0x0000
+
 uint16_t ram[0x10000];
 uint16_t ra, rb, rc, rx, ry, rz, ri, rj;
 uint16_t rpc, rsp, rex, ria;
@@ -20,6 +23,27 @@ uint16_t intq[MAX_INTQ_SIZE];
 unsigned int intq_size;
 uint8_t intq_head;
 
+void dumpregs()
+{
+    printf("%4s %4s %4s %4s %4s %4s %4s %4s %4s %4s %4s %4s\n",
+           "PC","SP","A","B","C","X","Y","Z","I","J","EX","IA");
+    printf("%04hx %04hx %04hx %04hx %04hx %04hx %04hx %04hx %04hx %04hx %04hx %04hx\n",
+           rpc, rsp, ra, rb, rc, rx, ry, rz, ri, rj, rex, ria);
+}
+
+void dump_ram(uint16_t addr, uint16_t count)
+{
+    uint16_t i, a;
+
+    for (i=0; i<count; i++) {
+        a = (addr + i) % sizeof(ram);
+        if ((i % 8) == 0)
+            printf("\n%04x: ", a);
+        printf("%04x ", ram[a]);
+    }
+    printf("\n");
+}
+
 void intq_push(uint16_t v)
 {
     if (intq_size < MAX_INTQ_SIZE) {
@@ -64,7 +88,21 @@ struct dev_entry {
 
 void debug_irqh()
 {
-    running = false;
+    switch (ra) {
+    case 0x0000:
+        running = false;
+        break;
+    case 0x0001:
+        dumpregs();
+        break;
+    case 0x0002:
+        dump_ram(ry, rx);
+        break;
+    case 0xffff:
+        rx = EMU_ID;
+        ry = EMU_VER;
+        break;
+    }
 }
 
 struct dev_entry iodevs[] = {
@@ -442,14 +480,6 @@ const op_t sops[] = {
     oNOP, oNOP, oNOP, oNOP, oNOP, oNOP, oNOP, oNOP      /* 18-1f */
 };
 
-void dumpregs()
-{
-    printf("%4s %4s %4s %4s %4s %4s %4s %4s %4s %4s %4s %4s\n",
-           "PC","SP","A","B","C","X","Y","Z","I","J","EX","IA");
-    printf("%04hx %04hx %04hx %04hx %04hx %04hx %04hx %04hx %04hx %04hx %04hx %04hx\n",
-           rpc, rsp, ra, rb, rc, rx, ry, rz, ri, rj, rex, ria);
-}
-
 void next()
 {
     uint16_t ir;
@@ -469,8 +499,6 @@ void next()
         }
     }
 
-    dumpregs();
-
     ir = ram[rpc++];
 
     opcode = ir & 0x001f;
@@ -518,24 +546,10 @@ int load_image(char *filename)
     }
 }
 
-void dump_ram(uint16_t addr, uint16_t count)
-{
-    uint16_t i, a;
-
-    for (i=0; i<count; i++) {
-        a = (addr + i) % sizeof(ram);
-        if ((i % 8) == 0)
-            printf("\n%04x: ", a);
-        printf("%04x ", ram[a]);
-    }
-    printf("\n");
-}
-
 int main(int argc, char *argv[])
 {
     if (argc > 1) {
         load_image(argv[1]);
-        dump_ram(0, 32);
         reset();
         while (running) next();
     }