MS BASIC on SBC6502

Source file

MS BASIC on SBC6502

Overview

The default setup in sbc.ini boots a kernel ROM plus an MS BASIC ROM, wired to VIC display, VIA keyboard input, and DISK MVP for LOAD/SAVE.

Start

./sbc6502 sbc.ini

You should see the BASIC banner and READY. prompt in the SDL window.

Common Commands

10 PRINT "HELLO WORLD"
20 GOTO 10
RUN

LIST
NEW

LOAD / SAVE

BASIC disk operations use host directory data/disk:

SAVE
LOAD

SBC-specific BASIC Addition

• CLS: clear screen and reset cursor

Relevant Memory Areas

$0000-$00FF   zero page
$0100-$01FF   stack
$0300-$7FFF   BASIC program + variables
$8000-$87FF   VIC text/color RAM
$8800-$880F   VIA 6522
$8810-$8813   UART 6551
$8820-$882F   DISK MVP
$8830-$8835   SOUND
$9000-$900F   VIC registers
$9010-$AF4F   VIC bitmap RAM
$C000-$CFFF   kernel ROM
$D000-$FFFF   MS BASIC ROM

Rebuild BASIC ROM

bash tools/make_msbasic_rom.sh

Source Locations

• port definitions: tools/msbasic_port/defines_sbc6502.s
• extra routines: tools/msbasic_port/sbc6502_extra.s
• load/save: tools/msbasic_port/sbc6502_loadsave.s
• iscntc hook: tools/msbasic_port/sbc6502_iscntc.s