Search found 89 matches

by Gigasoft
Fri Mar 19, 2010 9:59 pm
Forum: Megadrive/Genesis
Topic: Advice on the Art of Genesis level Building
Replies: 30
Views: 7782

In Mega Man 5, the GG code ATLKGL (C33C:60) enables debug keys on controller 2. Some of these are processed in the main game task (Task 0). These are Left (pauses the game) and Right (palette editor). Task 1 handles palette and background animations. Task 2 just starts up the other tasks. Task 3 is ...
by Gigasoft
Fri Mar 19, 2010 7:00 am
Forum: Megadrive/Genesis
Topic: Advice on the Art of Genesis level Building
Replies: 30
Views: 7782

Nope, not PC, Mega Drive. I used the same technique on the NES. I switch to loading task at the end of frame processing, and the VBL handler returns me back to where I was before. Many Capcom NES and SNES games have support for (non-preemptive) multitasking too in the code, although they don't usual...
by Gigasoft
Tue Mar 16, 2010 7:00 pm
Forum: Megadrive/Genesis
Topic: Advice on the Art of Genesis level Building
Replies: 30
Views: 7782

For tile updates, you could transfer a manageable number of tiles every frame until you're done. Uncompressing can be done in the background when the game is idle. In an upcoming game I'm making, I switch to a background task that performs loading of world data whenever I'm waiting for the next fram...
by Gigasoft
Wed Feb 24, 2010 8:51 am
Forum: Video Display Processor
Topic: Megadrive video timings
Replies: 120
Views: 46440

Is the CPU frozen during DMA even if it's running from RAM? Because Sega recommends triggering the DMA copy with the source operand in RAM if the copy is from ROM to avoid a hang.
by Gigasoft
Sun Feb 14, 2010 5:20 pm
Forum: Megadrive/Genesis
Topic: Z80 clocking
Replies: 7
Views: 2566

No, that's not true. The wait states would happen around 255714 times per second, which is a frequency much higher than what we can hear.
by Gigasoft
Mon Feb 08, 2010 2:42 pm
Forum: Megadrive/Genesis
Topic: Z80 clocking
Replies: 7
Views: 2566

Yes, using wait states would be a good idea.

All games I've disassembled use cycle counting to time DAC playback. I haven't heard of any games that use timers for anything but music timing.
by Gigasoft
Sun Feb 07, 2010 11:01 pm
Forum: Megadrive/Genesis
Topic: Z80 clocking
Replies: 7
Views: 2566

Digitized sounds would be off key. Usually, they're only used for drums, but Phantasy Star 4 has some melodic samples in it, and the music would not sound right.

If you can use a normal signal as a clock input, it shouldn't be hard to use the top bit of a counter counting to 15 as a clock signal.
by Gigasoft
Sat Feb 06, 2010 12:28 am
Forum: Demos
Topic: Happy New Year 2010 Demo
Replies: 10
Views: 4557

Sorry, my mistake. It should work now. Try downloading and testing it again.
by Gigasoft
Sat Jan 30, 2010 4:29 pm
Forum: Regen
Topic: Regen 0.972 and 0.972D
Replies: 193
Views: 66674

Well, Phantasy Star 4 uses a special I/O port to switch between SRAM and ROM, so that's probably unimplemented.
by Gigasoft
Mon Jan 18, 2010 1:21 am
Forum: Megadrive/Genesis
Topic: What kind of IA can use a 16bit game?
Replies: 9
Views: 4718

You probably don't need to do long calculations for every enemy every frame. The enemies can take turns doing AI calculations so that on frame 1, calculations are done for enemies 1-10, and on frame 2, calculations are done for enemies 11-20 and so on.
by Gigasoft
Sun Jan 03, 2010 8:53 pm
Forum: Video Display Processor
Topic: Relationship between VDP and User/Kernel Mode?
Replies: 22
Views: 7155

I use VINT as a timer, and I decrement each channel's timer according to an overflow value made by adding the song's speed to a global timer. That works out well. The YM2612 also has two programmable timers that you can poll. You don't need to share addresses between the two programs. You can just i...
by Gigasoft
Sun Jan 03, 2010 7:04 am
Forum: Regen
Topic: Regen 0.972 and 0.972D
Replies: 193
Views: 66674

When I was using the debugger the other day, it popped up new disassembly windows every time I traced or even when I tried to close the window.
by Gigasoft
Fri Jan 01, 2010 4:23 pm
Forum: Hardware
Topic: Gen cart pinout
Replies: 27
Views: 121558

Is this why my Game Genie makes strange buzzing noises in the background? Perhaps some current is leaking into one of these pins.
by Gigasoft
Fri Jan 01, 2010 2:31 am
Forum: Demos
Topic: Happy New Year 2010 Demo
Replies: 10
Views: 4557

Happy New Year 2010 Demo

Hey, I've created a little Mega Drive demo.

http://gigasoft.byethost15.com/ny2010.htm

Contains:
- 3D text
- Warping image
- Music