Hscrol d404 Write edit horizontal Fine Scroll Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit???? 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 dubai 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 Narrow width antic fetches the screen ram needed for Normal width. Likewise, for Normal width antic fetches the screen ram needed for Wide. Antic buffers the first few bytes read from screen memory that are sufficient to cover the 16 color clock range of movement.
As this vertically mirrors the glyph data before it is used, the effect appears inconsistent for antic mode 3 descenders with glyph bytes 6 oliver and 7 appearing at the bottom of the descender area. Dlistl/dlisth d402/D403 Write edit shadow: sdlstl/sdlsth 0230/0231 Display list pointer Bit 15 Bit 14 Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0???????????????? Antic begins executing the display list pointed to by the 16-bit address in registers dlistl/dlisth (D402-D403hex/ dec). 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.
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. 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.
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Antic dma and Player/Missile pattern register updates occur on each scan line regardless of resolution. When double line resolution is in effect the Player/Missile memory can be modified between the redundant dma fetches thus changing the pattern sent to the graf* registers and producing apparent Single line resolution Player/Missiles. Display list dma bit values: 00 - disable display list. 20 - enable display list. Playfield display requires that Display list dma is enabled, and a playfield width specified.
If either value is zero, then no Playfield display is generated. Chactl d401 Write edit shadow: chart 02F3 Character Control Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit Video reflect Video inverse fast video blank chactl controls character display. Character control bit values do the following actions: feature bits Value description Video blank 01 Inverse video characters display as blanks spaces. Video inverse 02 Inverse video characters appear as inverse video. (default) Video reflect 04 All characters are displayed vertically mirrored.
bit is unused, or should not be expected to be a certain value label Refer to a later explanation for the purpose of the bit. Dmactl d400 Write edit shadow: sdmctl 022f direct Memory Access (DMA) Control Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 - - display list dma player Missile resolution Player dma missile dma playfield Width Playfield Width dmactl. Playfield Width bit values: Playfield Width Bits 1:0 Description size 0 0 00 Disable playfield 0 1 01 Narrow playfield 128 color clocks/256 high-res pixels 1 0 02 Normal playfield 160 color clocks/320 high-res pixels 1 1 03 Wide playfield 192 color clocks/384 high-res pixels. Player/Missile dma bits values: Player/Missile dma bits 3:2 Description 0 0 00 Disable Player and Missile dma 0 1 04 Enable missile dma 1 0 08 Enable Player dma 1 1 0C Enable Player and Missile dma antic's Player/Missile dma feature reads bytes from memory. These bits turn on antic's transmission of Player data and Missile data to ctia/gtia. Ctia/gtia must also be configured to receive the data via its gractl register in order for Player/Missile dma to function as expected.
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. When enabled, Player/Missile dma occurs on every scan line in the visible display—from scan line 8 to 247. Therefore, the Player/Missile data in the memory map (see antic's pmbase ) above and below those scan line counts is unused and undisplayed. Player/Missile resolution bit values: 00 - double line resolution. Antic updates its dma fetch address every other scan line and updates the ctia/gtia player/Missile Graphics pattern registers every scan line, so that each Player/Missile byte pattern is two scan lines tall. When double line resolution is enabled ctia/gtia register vdelay (D01Chex/53276dec) works by masking updates on even scan lines which results in shifting the bit pattern of individual Players and Missiles down one scan line. 10 - single line resolution. A dma fetch and Player/Missile register update occurs on every scan line. Ctia/gtia register vdelay (D01Chex/53276dec) which masks updates on even scan lines effectively reduces Single line resolution to double line resolution.
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This problem is solved by Operating System Shadow registers implemented in regular ram as places to store the last value written to registers. Operating System Shadow registers are copied from ram to the hardware registers during the vertical blank. Therefore, any writes to hardware registers which have corresponding shadow registers will be overwritten by the value of the Shadow registers during the next vertical blank. Some Write hardware registers do not have corresponding Shadow registers. They can be safely written by an application without the value being overwritten during the vertical blank. If the application needs to know the last state of the register then it is the responsibility of the application to remember what japanese it wrote. Operating System Shadow registers also exist for some read registers where reading the value directly from hardware at an unknown stage in the display cycle may return inconsistent results. Name description read/Write hex Addr Dec Addr Shadow Name Shadow Hex Addr Shadow Dec Addr dmactl direct Memory Access Control Write d sdmctl 022F 559 chactl character Control Write d chart 02F3 755 dlistl display list pointer (low byte) Write d dlisth display list pointer. Bit may be either 0 or 1, and is used for a purpose.
C021698 — pal/secam: Used in Atari xl, and xe models. Intended to combine functions of the antic and gtia chips in one integrated circuit to reduce production costs of Atari computers and 5200 consoles. Two such prototype circuits were being developed, but neither entered production. Atari antic (C012296) pin-out Pin Name pin Number(s) Description A0 - a15 13, 12, 11, 10, 28, 27, 26, 25, 24, 23, 16, 22, 17, 18, 19, 20 Memory Address I/o an0 - an2 2, 3, 5 antic interface to ctia/gtia d0 -. Antic plan pulls pin low to halt the cpu for horizontal blank syncing (wsync) ref 8 ram refresh Output rnmi 6 nmi interrupt Input rst 36 Reset antic input R/W 14 read/Write I/O direction Vcc 21 Power 5 Volts Vss 1 Ground Ø0 34 Phase. Antic provides 15 read/Write registers controlling Playfield display parameters, dma for Player/Missile graphics, fine scrolling, light pen input, and interrupts. Hardware registers do not return the written values back when read.
ram for graphics features to be located almost anywhere in the 16-bit memory address range. This applies to: Display lists. Playfield Graphics data Character set fonts Player/Missile Graphics data versions edit by part number C012296 — ntsc: Used in Atari 400, 800, and 1200XL computers. 4 C014887 — pal/secam: Used in Atari 400 and 800 computers. C021697 — ntsc: Used in Atari 600xl, 800xl, and xe models.
Atari 5200 video game system released in 1982, which shares most of the same hardware as the 8-bit computers. Antic is responsible for the generation of playfield graphics which is delivered as a datastream to the related. The, cTIA/gtia provides the coloring of the playfield graphics, and is responsible for adding overlaid sprites referred to as "Player/Missile graphics" by Atari. Atari advertised it as a true microprocessor, in that it has an instruction set to run programs (called display lists ) to process data. Antic has no capacity for writing back computed values to memory, it merely reads data from memory and processes it for output to the screen, therefore it is not. Contents features edit The list below plan describes antic's inherent hardware capabilities meaning the intended functionality of the hardware by itself, not including results achieved by cpu-serviced interrupts or display kernels frequently driving register changes. Antic uses dma to read a program called the " Display list " controlling these Playfield features: 14 different Playfield graphics modes 6 character modes 4 types of font/glyph rendering 8 map modes Output a variable number of blank scan lines Playfield Text and Map. Other Register-based functions: Variable screen width up to horizontal overscan Define the distance of movement for Horizontal and Vertical Fine scrolling Provides real-time information of the electron beam's vertical screen location. Reads a light pen horizontal/vertical coordinates (crt only) Soft, re-definable character set.
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This article is about the Atari 8-bit display chip. For the magazine, see. For the surname, see, antić. For the london pub chain, see. Atari antic microprocessor on an Atari 130XE motherboard. Alphanumeric Television Interface controller 1 antic ) is an, lsi, asic dedicated to generating 2D computer graphics to be shown on a television screen or computer display. Under the direction of, jay miner, the chip was designed. Joe decuir, francois Michel, and Steve smith 2 for the, atari 8-bit family of home computers first shakespeare released in 1979 and was patented. 3, antic is also used in the.