diff --git a/Makefile b/Makefile
index 3d08835..6ad8604 100644
--- a/Makefile
+++ b/Makefile
@@ -13,6 +13,8 @@ endif
 ifdef DEBUG
 QEMU_ARGS += -chardev file,path=debugcon.log,id=seabios
 QEMU_ARGS += -device isa-debugcon,iobase=0x402,chardev=seabios
+QEMU_ARGS += -option-rom debug.rom
+DEBUGROM = debug.rom
 endif
 
 ifndef DISPLAY
@@ -26,6 +28,9 @@ default: kernel.rom
 kernel.rom: kernel/*.asm lib/*.inc
 	nasm -s -o $@ -I lib -I kernel kernel/main.asm && scripts/fix-rom.sh $@
 
+debug.rom: debug/*.asm lib/*.inc
+	nasm -s -o $@ -I lib -I debug debug/main.asm && scripts/fix-rom.sh $@
+
 boot/%.bin: boot/%.asm lib/*.inc
 	nasm -s -o $@ -I boot -I lib $<
 
@@ -38,11 +43,11 @@ fdimage.img: boot/floppy.bin kernel.rom
 clean:
 	rm -f *.com *.bin *.rom *.img *.log boot/*.bin
 
-qemu-rom: kernel.rom
+qemu-rom: kernel.rom $(DEBUGROM)
 	$(QEMU) $(QEMU_ARGS) -option-rom kernel.rom
 
-qemu-floppy: fdimage.img
+qemu-floppy: fdimage.img $(DEBUGROM)
 	$(QEMU) $(QEMU_ARGS) -boot c -hda fdimage.img
 
-qemu-serial: boot/serial.bin
+qemu-serial: boot/serial.bin $(DEBUGROM)
 	$(QEMU) $(QEMU_ARGS) -hda boot/serial.bin
diff --git a/kernel/debug.asm b/debug/debug.asm
similarity index 90%
rename from kernel/debug.asm
rename to debug/debug.asm
index 46cf138..05c7910 100644
--- a/kernel/debug.asm
+++ b/debug/debug.asm
@@ -116,11 +116,12 @@ isr_debug:
   pop cx
   pop dx
   pop bx
-  pop bp ; sp to be ignored
+  add sp, 2 ; ignore SP
+  pop bp
   pop bp
   pop si
   pop di
   pop ds
   pop es
-  pop ss
-  iret
\ No newline at end of file
+  add sp, 2 ; ignore SS
+  iret
diff --git a/debug/main.asm b/debug/main.asm
new file mode 100644
index 0000000..45ca7df
--- /dev/null
+++ b/debug/main.asm
@@ -0,0 +1,206 @@
+cpu 8086
+org 0x0000
+rom:
+  db 0x55, 0xAA
+.sectors:
+  db 0x00
+.init:
+  mov dx, isr_debug
+  mov al, 0x1
+  call intr_register
+  mov al, 0x03
+  call intr_register
+  retf
+
+.name:
+  db "rDebug", 0
+
+  times (0x18 - ($-$$)) db 0
+.pcir_ptr:
+  dw 0
+
+  times (0x1A - ($-$$)) db 0
+.pnp_ptr:
+  dw pnp
+
+pnp:
+  db "$PnP"
+.version:
+  db 1 ; version 1
+.length:
+  db 2 ; 2 * 16 length
+  dw 0 ; offset of next header
+  db 0
+.checksum:
+  db 0 ; checksum (filled by fix-rom)
+  dd 0 ; device identifier
+  dw 0 ; manufacturer string
+  dw rom.name ; product name string
+  db 0,0,0 ; device type string
+  db 0x20 ; device indicator, bit for "read cacheable" set
+  dw 0 ; boot connection vector
+  dw 0 ; boot disconnect vector
+  dw 0 ; bootstrap entry point
+  dw 0 ; reserved
+  dw 0
+
+putc:
+  push bx
+  push cx
+  mov ah, 0x0e
+  mov bx, 0x0000
+  int 0x10
+  pop cx
+  pop bx
+  ret
+
+intr_register:
+  ; DI = AL * 4
+  mov ah, 4
+  mul ah
+  mov di, ax
+
+  ; ES = 0
+  xor ax, ax
+  mov es, ax
+
+  ; store offset
+  mov ax, dx
+  stosw
+
+  ; store segment
+  mov ax, cs
+  stosw
+
+  ret
+
+; Names for words in debug frame
+; Two characters per word, 14 words total
+debug_frame_names:
+  ; general-purpose registers
+  db "AXCXDXBXSPBPSIDI"
+  ; extra registers
+  db "DSESSSIPCSFL"
+
+; Names for bits in debug_frame+26 (FL/Flags register)
+; One character per bit, 16 bits total
+debug_frame_flags:
+  db "++++ODIT"
+  db "SZ+A+P+C"
+
+; Print a single register from the frame
+; in	SI	frame offset for register
+debug_frame_register_print:
+  mov bx, debug_frame_names
+  mov al, [cs:bx+si] ; first name char load
+  call putc
+  mov al, [cs:bx+si+1] ; second name char load
+  call putc
+  mov al, '='
+  call putc
+  mov ax, [ss:bp+si] ; value load
+  ; prepare call to print_number
+  push bx
+  push cx
+  mov bx, 0x0010
+  mov cx, 3
+  call print_number_padded
+  pop cx
+  pop bx
+  mov al, ' '
+  call putc
+  ret
+
+debug_frame_print:
+  mov si, 0
+  mov cx, 8
+.reg1loop:
+  call debug_frame_register_print
+  add si, 2
+  loop .reg1loop
+
+  mov dx, [ss:bp+26]
+  mov di, debug_frame_flags
+  mov cx, 0x0010
+.flag_loop:
+  mov al, [cs:di]
+  inc di
+  cmp al, '+'
+  je .next
+  test dx, 0x8000
+  jnz .write
+  mov al, '-'
+.write:
+  call putc
+.next:
+  sal dx, 1
+  loop .flag_loop
+
+  call printf
+  db 0x0A, 0x0D, 0
+
+  mov si, 16
+  mov cx, 3
+.reg2loop:
+  call debug_frame_register_print
+  add si, 2
+  loop .reg2loop
+
+  mov ax, [bp+24]
+  mov bx, 0x0010
+  mov cx, 3
+  call print_number_padded
+
+  mov al, ':'
+  call putc
+
+  mov ax, [bp+22]
+  mov bx, 0x0010
+  mov cx, 3
+  call print_number_padded
+
+  call printf
+  db 0x0A, 0x0D, 0
+
+  ret
+
+; this prints registers
+; expect to be called as interrupt routine
+isr_debug:
+  push ss
+  push es
+  push ds
+  push di
+  push si
+  push bp
+  push sp
+  push bx
+  push dx
+  push cx
+  push ax
+
+  mov bp, sp
+  mov [bp+08], bp
+  add WORD [bp+08], 28
+
+  call printf
+  db 0x0A, 0x0D, 0
+
+  call debug_frame_print
+
+  pop ax
+  pop cx
+  pop dx
+  pop bx
+  pop bp
+  pop bp
+  pop si
+  pop di
+  pop ds
+  pop es
+  pop ss
+  iret
+
+%include "printf.inc"
+
+align 512
diff --git a/kernel/main.asm b/kernel/main.asm
index 6c91443..32cb154 100644
--- a/kernel/main.asm
+++ b/kernel/main.asm
@@ -1,15 +1,29 @@
 cpu 8086
 org 0x0000
+rom:
   db 0x55, 0xAA
-optrom_length:
+.sectors:
   db 0x00
-  jmp optrom_init
+.init:
+  push cs
+  pop es
 
-; reserved area
-times (0x1A - ($-$$)) db 0
+  mov di, start
+  mov ax, 0x18
+  call intr_register
+
+  retf
+.name:
+  db "ROM DOS", 0
+
+  times (0x18 - ($-$$)) db 0
+.pcir_ptr:
+  dw 0
+
+  times (0x1A - ($-$$)) db 0
+.pnp_ptr:
   dw pnp
 
-align 16
 pnp:
   db "$PnP"
 .version:
@@ -21,8 +35,8 @@ pnp:
 .checksum:
   db 0 ; checksum (filled by fix-rom)
   dd 0 ; device identifier
-  dw str_vendor ; manufacturer string
-  dw str_product ; product name string
+  dw 0 ; manufacturer string
+  dw rom.name ; product name string
   db 0,0,0 ; device type string
   db 0x20 ; device indicator, bit for "read cacheable" set
   dw 0 ; boot connection vector
@@ -31,40 +45,6 @@ pnp:
   dw 0 ; reserved
   dw 0
 
-str_vendor:
-  db "Nero", 0
-str_product:
-  db "Nero DOS ", 60, 234, 62, 0
-
-optrom_init:
-  push cs
-  pop es
-
-  mov di, isr_debug
-  mov ax, 0x1
-  call intr_register
-  mov ax, 0x3
-  call intr_register
-
-  mov di, start
-  mov ax, 0x18
-  call intr_register
-
-  retf
-
-announce:
-  push ds
-  push cs
-  push cs
-  pop ds
-  mov ax, str_product
-  push ax
-  call printf
-  db "%S (CS=%Xh)", 0x0A, 0x0D, 0x00
-  add sp, 4
-  pop ds
-  ret
-
 start:
   xor ax, ax
   mov ds, ax
@@ -73,8 +53,6 @@ start:
   mov sp, 0x800
   mov di, sp
 
-  call announce
-
   call drvtab_create
 
   push cs
@@ -86,6 +64,7 @@ start:
 .loop:
   mov ah, 0x01
   int 0x21
+  int3
   jmp .loop
 
   cli
@@ -112,9 +91,4 @@ isr_return:
 
 %include "chario.asm"
 
-%include "printf.inc"
-%include "print.asm"
-
-%include "debug.asm"
-
 align 512