How odd.
Wade.
The cartridge is more powerful than the console? :-D
How odd.
Wade. Q:Is it proper to eat cheeseburgers with your fingers? A:No, the fingers should be eaten separately. |
|
Yep
Still constrained by how video works on the Atari. There's not enough RAM for a frame buffer, so you must update the video chip's registers on every scanline.
There's 76 cycles of CPU time per scanline. One of the more common routines to update a single sprite & it's color (for the common line-by-line color change in later games) takes 26 cycles lda #SPRITEHEIGHT For my game Stay Frosty, I used a mask overlay, which greatly increased ROM usage but only took 21 cycles LDA (SpritePtr),y ; 5 PitFall 2 uses coprocessor, known as DPC (display processor chip), that knocked that down to 14 cycles LDA DF0DATAW ; 4 <--- DPC register The ARM cartridge has support to emulate the DPC so you can use it to play Pitfall 2. We modified it to take advantage of the capabilities of the ARM cartridge, such as monitoring what's read from the cartridge so we could override the LDA Immediate mode and reduce that down to 10 cycles. LDA #<DF0DATAW ; 2 The saved cycles can be used to do other video chip updates, giving you the ability to do better graphics than normal for the Atari. I posted sample code for DPC+, of which the last demo does 29 updates of the video chip over 2 scanlines. http://www.atariage....-dpc-programming/ |
|
I can see why you enjoy the challenge! :-)
Q:Is it proper to eat cheeseburgers with your fingers? A:No, the fingers should be eaten separately. |
|
digitized audio on the 2600
Yes - that primitive hardware can be made to play back digitized samples! It's limited to 4-bit samples. It can easily handle 8000 Hz, but this demo is at 4000 Hz due to RAM and ROM limitations for use in a game.
http://www.youtube.c...tch?v=NEDP0Ch0j8M |