Check out Atariage.com and the Atari 8-bit computer groups on Facebook. A buddy of mine is a demo coder of old on the Atari, cowrote "Intel Outside". The Atari 8-bit has more than the 6502 at 1,79mhz, It has two dedicated 40 pin coprocessors for graphics, another for sound, an IO chip, a simple MMU. What Atari did to allow these chips to busmaster is to add a halt line to the 6502. Initially this was done with a trio of 74ls chips, until Atari's own "Sally" version with the halt logic integral came into production. No halt line is the major reason we never saw 6502-based machines with front panels and blinkin' lights. 8080, 8085, z80, yes, but 6502 no. With Atari's rig, any 6502 could be such a monster, but Atari used it to share the bus. Antic can directly access memory without cpu intervention and vice-versa. Antic can switch video modes at each scanline, which amounts to a really huge number of possible 'modes' additional to the documented 15 modes Atari supplied. Most of what is being done here is likely artful Antic programming (called a display-list). This demo needs 320k, which is doggone big for a 6502 program. The CPU can modify the display list on the scan line as well, then let Antic do it's thing. You can get answers to how this is done at atariage for sure.
The music is awesome
Amazing. I know a couple things about 6502 coding and this is like watching a magic trick, I can't stop trying to figure out how it is done.
Check out Atariage.com and the Atari 8-bit computer groups on Facebook. A buddy of mine is a demo coder of old on the Atari, cowrote "Intel Outside".
The Atari 8-bit has more than the 6502 at 1,79mhz, It has two dedicated 40 pin coprocessors for graphics, another for sound, an IO chip, a simple MMU.
What Atari did to allow these chips to busmaster is to add a halt line to the 6502. Initially this was done with a trio of 74ls chips, until Atari's own "Sally" version with the halt logic integral came into production. No halt line is the major reason we never saw 6502-based machines with front panels and blinkin' lights. 8080, 8085, z80, yes, but 6502 no. With Atari's rig, any 6502 could be such a monster, but Atari used it to share the bus.
Antic can directly access memory without cpu intervention and vice-versa. Antic can switch video modes at each scanline, which amounts to a really huge number of possible 'modes' additional to the documented 15 modes Atari supplied. Most of what is being done here is likely artful Antic programming (called a display-list). This demo needs 320k, which is doggone big for a 6502 program. The CPU can modify the display list on the scan line as well, then let Antic do it's thing. You can get answers to how this is done at atariage for sure.