Add preliminary bootloader

This bootloader right now just prints the letter A, but should be capable of reading blocks from the SD card into memory.
2022-04-18 20:25:08 -05:00
parent 54328722ab
commit 9dd460a47f
10 changed files with 129 additions and 0 deletions
--- a/sw/bootloader/boot.s
+++ b/sw/bootloader/boot.s
@@ -0,0 +1,26 @@
+; We need to to read the boot sector from the
+; SD card, verify the last 2 bytes, then jump to the
+; beginning of it.
+
+.include "zeropage.inc"
+
+.import _load_bootsect
+
+.export _init, _boot
+
+.segment "STARTUP"
+
+_init:  jmp _boot
+
+.segment "CODE"
+
+_boot:  ldx #$ff
+        txs
+        cld
+
+        jsr _load_bootsect
+        jmp $1000
+
+.segment "SIGN"
+.byte $55
+.byte $aa