diff --git a/sw/boot.s b/sw/boot.s
index f71942c..269c5fd 100644
--- a/sw/boot.s
+++ b/sw/boot.s
@@ -1,15 +1,59 @@
-		.import _main
-		
-        .export __STARTUP__ : absolute = 1
+; ---------------------------------------------------------------------------
+; crt0.s
+; ---------------------------------------------------------------------------
+;
+; Startup code for cc65 (Single Board Computer version)
 
-		.segment "VECTORS"
-		
-		.addr _init
-		.addr _init
-		.addr _init
-		
-		.segment "STARTUP"
-		
-_init:		jsr _main
+.export   _init, _exit
+.import   _main
 
-end:		jmp end
+.export   __STARTUP__ : absolute = 1        ; Mark as startup
+.import   __RAM_START__, __RAM_SIZE__       ; Linker generated
+
+.import    copydata, zerobss, initlib, donelib
+
+.include  "zeropage.inc"
+
+.segment "VECTORS"
+
+.addr _init
+.addr _init
+.addr _init
+
+; ---------------------------------------------------------------------------
+; Place the startup code in a special segment
+
+.segment  "STARTUP"
+
+; ---------------------------------------------------------------------------
+; A little light 6502 housekeeping
+
+_init:    LDX     #$FF                 ; Initialize stack pointer to $01FF
+          TXS
+          CLD                          ; Clear decimal mode
+
+; ---------------------------------------------------------------------------
+; Set cc65 argument stack pointer
+
+          LDA     #<(__RAM_START__ + __RAM_SIZE__)
+          STA     sp
+          LDA     #>(__RAM_START__ + __RAM_SIZE__)
+          STA     sp+1
+
+; ---------------------------------------------------------------------------
+; Initialize memory storage
+
+          JSR     zerobss              ; Clear BSS segment
+          JSR     copydata             ; Initialize DATA segment
+          JSR     initlib              ; Run constructors
+
+; ---------------------------------------------------------------------------
+; Call main()
+
+          JSR     _main
+
+; ---------------------------------------------------------------------------
+; Back from main (this is also the _exit entry):  force a software break
+
+_exit:    JSR     donelib              ; Run destructors
+          BRK
diff --git a/sw/main.c b/sw/main.c
index 77caeb0..a09a475 100644
--- a/sw/main.c
+++ b/sw/main.c
@@ -6,6 +6,6 @@ int main() {
     uint16_t* seven_seg;
     seven_seg = (uint16_t*)SEVEN_SEG;
 
-    *seven_seg = 0xa5a5;
+    *seven_seg = 0xbabe;
     return 0;
 }