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First pass at integrating BASIC

This commit is contained in:
Seth Morabito 2014-07-27 13:50:24 -07:00
parent 1a39525929
commit 9e7042f604
2 changed files with 8725 additions and 4 deletions
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8691
basic.asm Normal file
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38
monitor.asm
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@ -5,6 +5,16 @@
;;; Last Updated: 2014-JUL-03
;;;
.feature labels_without_colons
.include "basic.asm"
;;;************************************************************************
;;; Enhanced 6502 BASIC Integration
;;;************************************************************************
IRQ_vec = VEC_SV + 2
NMI_vec = IRQ_vec + $0A
;;;************************************************************************
;;; Macro Definitions.
;;;************************************************************************
@ -42,8 +52,6 @@
;;; Non-monitor code, e.g. BASIC, utilities, etc., resides
;;; in the bottom 14KB of ROM
;;;************************************************************************
.segment "CODE"
.org $C000
;;; ----------------------------------------------------------------------
;;; Memory Definitions
@ -84,6 +92,11 @@
IOCMD = IORW+2 ; ACIA command register
IOCTL = IORW+3 ; ACIA control register
.segment "CODE"
.org $C000
;; BASIC lives here.
;;;************************************************************************
;;; ROM monitor code resides in the top 2KB of ROM
;;;************************************************************************
@ -119,6 +132,12 @@ HRESET: LDA #$02 ; Clear page 2
STA (STRLO),Y
BNE @loop
;; Set up vectors for BASIC.
VECS: LDA LABVEC-1,Y
STA VEC_IN-1,Y
DEY
BNE VECS
;; Start the monitor by printing a welcome message.
STR BANNR
@ -610,8 +629,8 @@ CIN: LDA IOST
CMP #'{' ; >= '{'?
BCS @done ; Yes, done.
AND #$5f ; No, convert lower case -> upper case,
@done: RTS ; and return.
@done: SEC ; Flag byte received, for BASIC
RTS ; and return.
;;; ----------------------------------------------------------------------
;;; Print the null-terminated string located at STRLO,STRHI
@ -625,10 +644,21 @@ STOUT: LDY #$00 ; Initialize string pointer
BNE @loop ; Continue
@done: RTS ; Return
STUB_SAVE:
STUB_LOAD:
RTS
;;; ----------------------------------------------------------------------
;;; Data
;;; ----------------------------------------------------------------------
;;; Vectors used by EhBASIC
LABVEC: .word CIN
.word COUT
.word STUB_SAVE
.word STUB_LOAD
;;; Strings
BANNR: .byte "RETROCHALLENGE 2014 ROM MONITOR",0
HELPS: .byte "COMMANDS ARE:",CR,LF
.byte "H HELP",CR,LF