Get super simple kernel code running

2023-08-26 13:09:02 -07:00
parent 3487f35af8
commit 0247565f49
5 changed files with 205 additions and 382 deletions
--- a/sw/kernel/boot.s
+++ b/sw/kernel/boot.s
@@ -5,7 +5,7 @@
 ; Startup code for cc65 (Single Board Computer version)

 .export   _init, _exit
-.import   _main
+.import   _main, _cputc

 .export   __STARTUP__ : absolute = 1        ; Mark as startup
 .import   __STACKSTART__, __STACKSIZE__       ; Linker generated
@@ -22,7 +22,12 @@
 ; ---------------------------------------------------------------------------
 ; A little light 6502 housekeeping

-_init:    LDX     #$FF                 ; Initialize stack pointer to $01FF
+_init:    
+            lda #'A'
+            jsr _cputc
+@1:         jmp @1
+
+          LDX     #$FF                 ; Initialize stack pointer to $01FF
          TXS
          CLD                          ; Clear decimal mode