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Console output

This commit is contained in:
Seth Morabito 2014-07-03 15:55:57 -07:00
parent b64b1769bd
commit ee5c2735e3
2 changed files with 54 additions and 30 deletions
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79
monitor.asm
View File

@ -1,31 +1,60 @@
;;
;; Retrochallenge Summer 2014
;; 6502 ROM Monitor
;;
;;;
;;; Retrochallenge Summer 2014
;;; 6502 ROM Monitor
;;;
;;************************************************************************
;; Non-monitor code, e.g. BASIC, utilities, etc., resides
;; in the bottom 14KB of ROM
;;************************************************************************
.segment "CODE"
.org $C000
;;;************************************************************************
;;; Non-monitor code, e.g. BASIC, utilities, etc., resides
;;; in the bottom 14KB of ROM
;;;************************************************************************
.segment "CODE"
.org $C000
;;************************************************************************
;; ROM monitor code resides in the top 2KB of ROM
;;************************************************************************
.segment "MONITOR"
.org $FB00
;;; ----------------------------------------------------------------------
;;; IO Addresses
;;; ----------------------------------------------------------------------
START: LDA #$00 ; Set zero flag
BEQ * ; Loop forever
IORW = $8800 ; ACIA base address, R/W registers
IOST = IORW+1 ; ACIA status register
IOCMD = IORW+2 ; ACIA command register
IOCTL = IORW+3 ; ACIA control register
;;************************************************************************
;; Reset and Interrupt vectors
;;************************************************************************
.segment "VECTORS"
.org $FFFA
;;;************************************************************************
;;; ROM monitor code resides in the top 2KB of ROM
;;;************************************************************************
.segment "MONITOR"
.org $FB00
.word START ; NMI vector
.word START ; Reset vector
.word START ; IRQ vector
START:
INITIO: LDA #$1D ; Set ACIA to 8N1, 9600 baud
STA IOCTL ; ($1D = 8 bits, 1 stop bit, 9600)
LDA #$0B ; ($0B = no parity, irq disabled)
STA IOCMD ;
A_LOOP: LDA #'@' ; Print "@" to the terminal, forever.
JSR COUT ; Call COUT
BNE A_LOOP ; Accumulator is "@", so not 0 -- loop.
;;;
;;; Print the character in the Accumulator to the ACIA's output
;;;
COUT: PHA ; Save accumulator
@loop: LDA IOST ; Is TX register empty?
AND #$10
BEQ @loop ; No, wait for empty
PLA ; Yes, restor char & print
STA IORW
RTS ; Return
;;;************************************************************************
;;; Reset and Interrupt vectors
;;;************************************************************************
.segment "VECTORS"
.org $FFFA
.word START ; NMI vector
.word START ; Reset vector
.word START ; IRQ vector

5
symon.config
View File

@ -11,8 +11,3 @@ DATA: load = ROM1, type = ro;
MONITOR: load = MONITOR, type = ro;
VECTORS: load = ROMV, type = ro;
}
SYMBOLS {
__STACKSIZE__ = $0300;
}