Meta [ Title: "Rainbow Atari 8-bit demo, assembly version" Author: "Kaj de Vos" Rights: "Copyright (c) 2020-2022 Kaj de Vos" License: { PD/CC0 http://creativecommons.org/publicdomain/zero/1.0/ } ] Unsafe!!! [ ; Define fixed memory addresses Constant reference volatile byte! [ ; Operating system software addresses RTCLOK3= ~14 SDMCTL= ~022F ; ANTIC hardware addresses COLBK= ~D01A WSYNC= ~D40A VCOUNT ] ; Switch off display DMA LDA 0 STA SDMCTL Forever: ; Pick rainbow colour LDA VCOUNT ASL-A ; Scroll the rainbow CLC ADC RTCLOK3 STA WSYNC ; Wait a scanline STA COLBK ; Paint the background CLV BVC forever ]