; CHIBI PC-09 Prototype #1 Boot ROM
; (Copyright (c) 2024 Amber Zeller

; UART registers
UART = $7F00

; When DLAB = 0
BUFR = UART    ; TX/RX Buffer (Read for RX, Write for TX)
IER = UART + 1 ; Interrupt Enable Register
IIR = UART + 1 ; Interrupt Enable Register (Upon Read)
; When DLAB = 1
DLL = UART     ; Divisor Latch (LSB)
DLM = UART + 1 ; Divisor Latch (MSB)

FCR = UART + 2 ; FIFO Control Register (Upon Write)
LCR = UART + 3 ; Line Control Register
MCR = UART + 4 ; MODEM Control Register
LSR = UART + 5 ; Line Status Register
MSR = UART + 6 ; MODEM Status Register
SCR = UART + 7 ; Scratch Register (Not for control just spare RAM)

;  SECTION code

  org $8000

RESET:
  sta $cc
  jmp RESET
  fdb RESET

;  ENDSECTION

;  SECTION vectors
  org $FFF0
  ; Reset/Interrupt Vectors
  fdb  $0000 ; Reserved
  fdb  $0000 ; SWI3
  fdb  $0000 ; SWI2
  fdb  $0000 ; FIRQ
  fdb  $0000 ; IRQ
  fdb  $0000 ; SWI
  fdb  $0000 ; NMI
  fdb  RESET ; Reset
;  ENDSECTION