display. Character control bit values do the following actions: The CHACTL Video Inverse and Video Blank bits affect the display of characters in ANTIC Text Modes 2 and 3 which have the high bit set (characters $80 through $FF). Toggling the values of the CHACTL bits allow blinking or blanking these characters globally for the entire display. Video Inverse and Video Blank enabled together result in reverse video characters displayed as an inverse blank space. Video Inverse and Video Blank bits work in ANTIC modes 2 and 3, and have no effect on the other text modes 4, 5, 6, and 7. The Video Reflect bit affects all Text Modes. Video Reflect is useful for situations requiring mirroring effects without defining a new character set. An ideal use is card games displaying accurate card faces showing upside down suits. As this vertically mirrors the glyph data before it is used, the effect appears inconsistent for ANTIC Mode 3 descenders with glyph bytes 6 and 7 appearing at the bottom of the descender area. DLISTL/DLISTH $D402/$D403 Write SHADOW: SDLSTL/SDLSTH $0230/$0231 Display List Pointer ANTIC begins executing the Display List pointed to by the 16-bit address in registers DLISTL/DLISTH (D402-D403hex/54274-54275dec). The address registers are updated during Display List execution by ANTIC's JMP (Jump) and JVB (Jump and wait for Vertical Blank). The address is also updated by the Operating System's Vertical Blank Interrupt (VBI) routine using the values in shadow registers SDLSTL/SDLSTH (0230-0231hex/560-561dec). When the OS Vertical Blank Interrupt is enabled, direct updates to the ANTIC DLIST registers by the CPU or the ANTIC Jump instructions will be overwritten by the OS during the next Vertical Blank by the values in the shadow registers. Therefore, page flipping implemented by Display Lists that point to the next Display List in series will not operate as expected unless the Vertical Blank interrupt is disabled. HSCROL $D404 Write Horizontal Fine Scroll This register specifies the distance of the Horizontal fine scrolling shift in color clocks. Only the lowest 4 bits are significant. The value range of 16 color clocks allows ANTIC to shift Mode 2 Text four characters, and Mode 6 text two characters before a coarse scroll is needed. When Horizontal scrolling is enabled for a mode line ANTIC fetches the next size increment greater than the current screen width to provide the buffer of data subject to the horizontal scrolling control. When displaying