Save Accumulator on stack LDA #$9C ; Load light blue (color $9, luminance $C) STA WSYNC ; Wait to sync to the end of the scanline STA COLBK ; Set the background PLA ; Restore Accumulator from stack RTI ; The end. Player/Missile Graphics Most Player/Missile graphics functionality is in the domain of the CTIA/GTIA chip. CTIA/GTIA controls position, size, color, priority, and collision detection for Player/Missile graphics objects, but its actual shape rendering implementation goes no farther than a single byte pattern per object presented uniformly on all scan lines. (The patterns are set in CTIA/GTIA's GRAF* graphics pattern registers.) In the end, by itself CTIA/GTIA generates Player/Missile objects as only vertical stripe patterns on the screen. ANTIC's design includes DMA capability so that it may read its Display List and Playfield graphics data. This direct memory access capability is leveraged to read data on behalf of CTIA/GTIA and update the GRAF* graphics pattern registers as each display scan line is generated. In this way ANTIC provides Player/Missile objects with patterns that vary over the height of the screen and so appear as traditional "sprite" graphics. Bits 2 and 3 of ANTIC's DMACTL register (shadowed by SDMCTL) control ANTIC's retrieval of Player/Missile data to update CTIA/GTIA graphics pattern registers. DMACTL Player/Missile DMA control bits values (bits [3:2]): - Disable Player and Missile DMA - Enable Missile DMA - Enable Player DMA - Enable Player and Missile DMA Missile DMA can be enabled without player DMA. However, when Player DMA is enabled, Missile DMA automatically occurs to keep the DMA timing consistent, but the data is not delivered to the Missile's GRAFM register. Bit 4 (value hex/16dec) of the DMACTL register controls the frequency of new data retrieval. ANTIC retrieves data and updates CTIA/GTIA every scan line. The DMACTL resolution settings affect how often ANTIC increments its internal DMA pointer for fetching new data. Single Line resolution Player/Missile graphics increments the DMA address every scan line, and Double Line resolution increments the DMA address with every even scan line. The DMACTL bit values for Player/Missile resolution: - Double line resolution. New data is fetched by DMA on even scan lines, but an update to CTIA/GTIA Player/Missile Graphics pattern registers still occurs on every scan line. Consequently, each Player/Missile byte pattern is two scan lines tall. When Double line resolution is enabled CTIA/GTIA register VDELAY (D01Chex/53276dec) can be used to mask