[atari7800] Re: Yet Another Kick In The Head!
- From: "Eric Ball" <ek-ball@xxxxxxxxxx>
- To: <atari7800@xxxxxxxxxxxxx>
- Date: Fri, 12 Nov 2004 17:33:15 -0500
> Only 19 scanlines of VBLANK? Only 2166 cycles for game calcs per frame?
Who the hell thought that was acceptable? That's less than half the 2600 for
crying out loud!! Why does MARIA need to halt the 6502? Why doesn't MARIA
just run in the background, like, oh, EVERY OTHER SYSTEM AFTER THE 2600!!!
MARIA needs to halt the 6502 because it shares the memory bus with it. I
don't know how the Atari 8bits/5200 work, but the NES which has a separate
memory bus for the GPU.
Anyway, it's a little better than that. MARIA only halts the 6502 while
it's reading from memory. So most of the cycles during the offscreen potion
(~50 lines) are also available. And if you don't use every cycle per line
the 6502 will get some more CPU time.
> It also flickers like crazy because my routines are too slow to complete
every frame (I'm rebuilding the Display Lists from scratch each frame which
may no be the best way to handle things) since there only 2166 cycles
available (!!!!!).
Yeah, for my balldemo http://www.atariage.com/users/ericball/balldemo.html
each sprite requires 224 cycles, or two scanlines to add to the display
list. I don't know if there is a more efficient way to do it.
Other related posts:
