Friday, January 29, 2021

how the atari 2600 merges time and space

"Man, you must have a deep understanding of TIA. I think for a lot of casual atari devs (funny that that's not a contradiction in terms, quite), everything is just there and kind of arbitrary, but you must have some idea of like... how the player 'tripler' flag change circuits."

"As a matter of fact, all sprites on the VCS are represented as counters that increment with the pixel clock (and wrap at 160). These go into a decode matrix that triggers drawing when certain trip points are reached. Changing the number of copies activates different parts of the decode matrix --- if you have three copies, drawing is triggered for tree different counter values."
Me and Christian Speckner, author of the excellent Stellerator Atari 2600 emulator
We're having a cordial conversation about programming (both Atari and modern web) on the Atari Age forums, a spin off of my recent Sisyphus project.

His point blew my mind a little bit... (especially interesting since he gives props to my early 2600 tutorials helping him when he first started out) I've dabbled a bit in Atari and read "Racing the Beam", but never thought about this particular merge of Time and Space: everything that puts a graphic in the right place is fundamentally based on these timers! (The amazingness of this point probably has a pretty small audience, but still...)

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