mirror of
https://github.com/RevCurtisP/C02.git
synced 2024-11-29 16:51:10 +00:00
128 lines
4.0 KiB
Plaintext
128 lines
4.0 KiB
Plaintext
; c02 Program Initialization Code for Unexpanded VIC-20
|
|
|
|
;ASCII Control Codes Equivalents
|
|
CR EQU $0D ;Carriage Return
|
|
LF EQU $11 ;Line Feed (Cursor Down)
|
|
DEL EQU $14 ;Delete
|
|
HT EQU $1D ;Horizontal Tab (Cursor Right)
|
|
VT EQU $91 ;Vertical Tab (Cursor Up)
|
|
FF EQU $93 ;Form Feed (Clear Screen)
|
|
BS EQU $9D ;Backspace (Cursor Left)
|
|
|
|
;PETSCII Key Mappings
|
|
DELKEY EQU $14 ;Delete/Backspace Key (Delete)
|
|
ESCKEY EQU $03 ;Escape/Stop Key (RUN/STOP)
|
|
RTNKEY EQU $0D ;Return/Enter Key (RETURN)
|
|
|
|
;Standard Library Constants
|
|
FOMAX EQU 7 ;Maximum Number of Open Files
|
|
FNMAX EQU 16 ;Maximum Filename Length
|
|
|
|
;Zero Page Locations
|
|
SRCLO EQU $FB ;String Pointer (stdio.asm)
|
|
SRCHI EQU $FC ;Free Byte for User Programs
|
|
DSTLO EQU $FD ;Free Byte for User Programs
|
|
DSTHI EQU $FE ;Free Byte for User Programs
|
|
|
|
;Other RAM Locations
|
|
TEMP0 EQU $0310 ;Free Byte for User Programs
|
|
TEMP1 EQU $0311 ;Free Byte for User Programs
|
|
TEMP2 EQU $0312 ;Free Byte for User Programs
|
|
TEMP3 EQU $0313 ;Free Byte for User Programs
|
|
FTBL EQU $0334 ;File Table (files.a02)
|
|
TBFFR EQU $033C ;Cassette I/O Buffer
|
|
user12 EQU $03FC ;Free Byte for User Programs
|
|
user13 EQU $03FD ;Free Byte for User Programs
|
|
user14 EQU $03FE ;Free Byte for User Programs
|
|
STKPTR EQU $03FF ;Stack Pointer Storage
|
|
|
|
;Video RAM and ROM
|
|
VICSCN EQU $1E00 ;Video Screen Memory Area (Unexpanded)
|
|
CHRROM EQU $8000 ;Character Generator ROM
|
|
VICCLR EQU $9600 ;COLOR RAM (UNEXPANDED)
|
|
|
|
;Kernal Routines
|
|
SETMSG EQU $FF90 ;Control System Message Output
|
|
SETLFS EQU $FFBA ;Set up Logical File
|
|
READST EQU $FFB7 ;Read Status Word
|
|
SETNAM EQU $FFBD ;Set File Name
|
|
OPEN EQU $FFC0 ;Open a Logical File
|
|
CLOSE EQU $FFC3 ;Close Logical File
|
|
CHKIN EQU $FFC6 ;Open Channel for Input
|
|
CHKOUT EQU $FFC9 ;Open Channel for Output
|
|
CLRCHN EQU $FFCC ;Clear I/O Channels
|
|
CHRIN EQU $FFCF ;Input Character to Channel
|
|
CHROUT EQU $FFD2 ;Output Character to Channel
|
|
GETIN EQU $FFE4 ;Read Character from Keyboard Buffer
|
|
CLALL EQU $FFE7 ;Close All Files
|
|
|
|
;Machine Language Basic Stub
|
|
ORG $A000 ;Start
|
|
START: TSX ;Get Stack Pointer
|
|
STX STKPTR ;and Save for Exit
|
|
JMP MAIN ;Execute Program
|
|
|
|
EXIT: LDX STKPTR ;Retrieve Saved Stack Pointer
|
|
TXS ;and Restore It
|
|
RTS ;Return to BASIC
|
|
|
|
;Poll Keyboard for Character
|
|
PLKEY EQU GETIN ;Read Character from Keyboard Buffer
|
|
|
|
;Get Character from Keyboard
|
|
GETKEY:
|
|
;Wait for Character from Keyboard
|
|
RDKEY: JSR PLKEY ;Poll Keyboard
|
|
BEQ GETKEY ;If No Key, Loop
|
|
RTS
|
|
|
|
;Print Character to Console
|
|
PRCHR EQU CHROUT ;
|
|
|
|
;Delete Previous Character
|
|
DELCHR: LDA #$9D ;Load Cursor Left into Accumulator
|
|
JSR PRCHR ; and Print it
|
|
LDA #$14 ;Load Delete into Accumulater
|
|
JMP PRCHR ; and Print it
|
|
|
|
;Advance Character to Next line
|
|
NEWLIN: LDA #$0D ;Load C/R into Accumulator
|
|
JMP PRCHR ; and Print it
|
|
|
|
;Print Byte as Two-Digit Hex Number to Console
|
|
PRBYTE: PHA ;Save Accumulater
|
|
LSR ;Shift Hi Nybble to Low Nybble
|
|
LSR
|
|
LSR
|
|
LSR
|
|
JSR PRHEX ; and Print it
|
|
PLA ;Restore Accumulator
|
|
; and fall into prhex
|
|
|
|
;Print Low Nybble as Hex Digit to Console
|
|
PRHEX: AND #$0F ;Strip High Nybble
|
|
CMP #$0A ;If Low Nybble >= 10
|
|
BCC PRHEXC ;
|
|
ADC #$06 ; Convert ':' to 'A'...
|
|
PRHEXC: ADC #$30 ;Convert to ASCII Character
|
|
JMP PRCHR ;Print Hex Digit and Return
|
|
|
|
;Functions to set String Pointers
|
|
;Used by memory, stdio, stdlin, string, and stringx libraries
|
|
|
|
;Initialize Destination String Pointer and Index
|
|
SETDST: STX DSTLO ;Save Destination String Pointer
|
|
STY DSTHI
|
|
RTS
|
|
|
|
;Initialize Source String Pointer and Index
|
|
SETSRC: STX SRCLO ;Save Source String Pointer
|
|
STY SRCHI
|
|
LDY #$00 ;Initialize Index Into String
|
|
RTS
|
|
|
|
;Retrieve Source String Pointer
|
|
GETSRC: LDX SRCLO
|
|
LDY SRCHI
|
|
RTS
|
|
** |