Subject: [stella] What would you do with more RAM?|
From: "Andrew Davie" <atari2600@xxxxxxxxxxxxx>
Date: Thu, 1 May 2003 16:23:37 +1000
I was just thinking about the soon-to-come cartridges which support extra RAM. What kind of possibilities will it open up for the '2600? Of course, games with large modifyable maps - like Boulderdash - would be made possible, and perhaps even interesting variations of existing game - perhaps BASIC could be improved enough to actually be useful?
Actually, RAM opens up lots of possibilities - for example, if you had 256 bytes reserved for each player, then you could have 'strip' sprites basically like the Atari 400/800. To modify the vertical position of a player requries you to 'draw' the player shape in the correct spot in the strip of RAM - but, and here's the beautiful bit, to actually draw the player in the kernel it's just...
That's just, what, 8 cycles per player. Neat. No skipdraw trickery, and to have multiple players vertically, you just draw multiple players in the RAM strip. YOu can have as many as you want, and they can overlap fine, and they won't flicker when vertically overlapping. Neat... again.
RAM also offers pure bitmap graphics - if one were using Interleaved Chronocolour (TM), for example, then one might need 3 (colour planes) x 6 (bytes/line) x 192 (lines) = 3456 bytes (actually you could squash it to 5 bytes/line at the cost of cycles - but let's assume we have the RAM and use it) and we'd have 8-colour playfields (2^3) and many many more game possibilities would be open to us. Since the Interleaved Chronoblah blah (tm) stuff is essentially an asymmetrical playfield with time multiplexing of colour, and combined with the 8 cycles/player... hell, there'd still be heaps of cycles/line to do other stuff.
Interleblah blah blah (TM) screens must change the PF colour to a known value (lda #, sta COLUPF = 5 cycles), and then 6 x lda stripX,y / sta PFn = 48 cycles), add the two sprites (16 cycles) and that's 64 cycles per line and you still have a single line kernel, you've got full-colour (well, 8-colour) Interlblah blah blah (TM) graphics AND both sprites and 12 cycles still left to play with. I've already done a mockup of Donkey Kong, and it looks pretty good....
So, IMHO... extra RAM is the next big thing (TM) for '2600. What other games would you guys tackle?