minimum functional bootcode

2024-11-21 12:15:27 -05:00
parent dcc1bea405
commit cea8a54ebf
3 changed files with 31 additions and 16 deletions
--- a/code/boot/boot.bin
+++ b/code/boot/boot.bin
--- a/code/boot/boot.s
+++ b/code/boot/boot.s
@@ -24,9 +24,23 @@ SCR = UART + 7 ; Scratch Register (Not for control just spare RAM)
  org $8000

 RESET:
-  sta $cc
-  jmp RESET
-  fdb RESET
+  ; UART Setup
+  lda %11000001 ; 8n1 serial, enable DLAB
+  sta LCR
+
+  lda $00       ; Set divisor to 12 (9600 baud)
+  sta DLL
+  lda $0C
+  sta DLM
+
+  lda %11000000 ; 8n1 serial, disable DLAB
+  sta LCR
+
+  lda %01000000 ; Enable RTS
+  sta MCR
+
+  lda 'H        ; send H
+  STA BUFR

 ;  ENDSECTION

--- a/code/boot/boot.s19
+++ b/code/boot/boot.s19
@@ -1,5 +1,6 @@
 S01800005B6C77746F6F6C7320342E32335D20626F6F742E73BF
-S10A800097CC7E8000800094
+S113800096C1B77F039600B77F00960CB77F0196A1
+S1118010C0B77F039640B77F049648B77F0041
 S113FFF0000000000000000000000000000080007D
-S5030002FA
+S5030003F9
 S9030000FC