Information AboutAntic |
| CATEGORIES ABOUT ANTIC | |
| graphics chips | |
| microprocessors | |
| atari 8-bit family | |
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ANTIC ('''''A'''lpha-'''N'''umeric '''T'''elevision '''I'''nterface '''C'''ircuit'') was an early video system chip used in the Atari 8-bit Family of Microcomputer s as well as the Atari 5200 the 1980s . ANTIC was a Microprocessor dedicated to generating 2D Computer Graphics to be shown on a Television screen or Computer Display . It was a true microprocessor, in that it had an '' Instruction Set '' to run ''programs'' (called '' Display List s'') to process '' Data ''. The display list and the display data were written into RAM by a 6502 -compatible CPU . The ANTIC retrieved that information from RAM using a technique known as Direct Memory Access (DMA) . It processed the higher level instructions in the display list and translated these instructions into a real-time stream of simpler instructions to the CTIA Chip , a combination providing for 12 graphics modes. With the more advanced GTIA , 16 modes were available. ANTIC's most notable features were:
ANTIC had four types of instructions:
Each instruction had additional options by setting specific bits:
Although ANTIC was a microprocessor, its program counter was only 10-bits long. This meant the ''display list'' needed a JMP (Jump) instruction to cross a 1K boundary. A LMS (Load Memory Scan) was needed for data crossing a 4K boundary. Finally, a JVB (Jump on Vertical Blank) instruction was placed at the end of the ''display list''. The entire display had to equal 192 scan lines. --Display list in example program:-- You have to write the following program to Basic (it usually write READY on blue screen, after turning ON computer. Every line, separate by pressing enter (on Atari keypad it is marked by "Return"). Lines are marked by numbers (10, 20 etc.). Run it by typing "RUN" and pressing enter('return'). Wait until all numbers end listing, and write PRINT USR(30720) and hit enter('return'). The PROGRAM displaying a GREEN PIXEL in Basic graphic mode 3, and lines in Basic mode 0. Tested on Atari 65 XE. 10 REM REDELERT 2006 20 FOR N=30720 TO 30829 30 READ D 34 ? N 35 POKE N,D 37 NEXT N 40 DATA 169,112,141,0,128,141,1,128 45 DATA 141,2,128,169,66,141,3,128 50 DATA 169,0,141,4,128,169,130 55 DATA 141,5,128,169,2,141,6,128 60 DATA 141,7,128,169,72,141,8,128 65 DATA 169,0,141,9,128,169,140 70 DATA 141,10,128,169,8,141,11,128 75 DATA 141,12,128,141,13,128,141,14 80 DATA 128,169,65,141,15,128,169,0 85 DATA 141,16,128,169,128,141,17,128 90 DATA 169,0,141,48,2,169,128,141 95 DATA 5,141,6,150,169,150,141,7,150 100 DATA 5,141,6,150,169,150,141,7,150 105 DATA 169,2,141,11,140,5,150 EXTERNAL LINKS
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