Search found 293 matches
- Wed Apr 07, 2010 5:39 am
- Forum: Video Display Processor
- Topic: Understanding the VDP's scrolling capabilities.
- Replies: 67
- Views: 81526
When it comes to scrolling abilities I feel the two systems are equally matched if you consider raster interrupts to be a suitable equivalent to HDMA. The only major differences are that the SNES has for scrolling are: - Offset per tile mode (seldom used) - Can scroll 1-tile wide columns (MD does 2-...
- Wed Apr 07, 2010 4:45 am
- Forum: Video Display Processor
- Topic: How does Sonic2 handle sprites for interlace mode?
- Replies: 7
- Views: 10126
Re: How does Sonic2 handle sprites for interlace mode?
With this method for Sonic2 I'm only able to see sprites if I subtract 224 from their y position - and I mainly see the sprites of the bottom half of the interlace display (Tails' screen). For the normal and single density interlace modes bits 8-0 of the sprite Y coordinate are used. In the double ...
- Wed Mar 17, 2010 3:14 am
- Forum: Megadrive/Genesis
- Topic: DMA instruction from RAM
- Replies: 3
- Views: 3849
Re: DMA instruction from RAM
However, I recall reading somewhere a discussion about a particular game which uses DMA transfers just fine, but doesn't use RAM at all. I wanted to find this discussion to make a note of it for my own code, but I couldn't find it at all. Does anyone know what I'm talking about? I'd like to know to...
- Fri Feb 26, 2010 11:05 pm
- Forum: Video Display Processor
- Topic: Megadrive video timings
- Replies: 123
- Views: 170700
About that, this is how it's done in Genesis Plus (source address registers as well) but it has not been confirmed to be the case on real hardware, it would need to be tested but it does not seem to break any games so far. If you are referring to how the source and length registers get updated duri...
- Sat Jan 02, 2010 5:05 am
- Forum: Video Display Processor
- Topic: Sprite Table Address Wierdness
- Replies: 16
- Views: 13567
The VDP has an internal copy of the sprite table, however only the Y position and sprite size information is stored. The X position and attribute word (name,palette,flip,priority) are not stored in it. Whenever you write to VRAM the VDP checks if the address is within the range of the sprite table (...
- Sat Jul 19, 2008 1:42 am
- Forum: Cartridge
- Topic: The not so famous /YS signal
- Replies: 28
- Views: 45196
Awesome stuff, in that doc, but the SPA/B pin and the color bus need to be activated in a register beforehand, else they only output internal noise (color bus) Methinks that they are enabled in bit4 in reg 0x0C and bit7 in reg 0x0B, respectively :wink: Bit 7 of $8B "connects" the external 68000 add...
- Fri Jul 18, 2008 10:59 pm
- Forum: Pico
- Topic: Emulating Sega Pico
- Replies: 33
- Views: 67239
Re: Emulating Sega Pico
The ADPCM chip is a NEC uPD7759 that has been rebranded by Sega. Here's the datasheet for the same 52-pin QFP version of the chip the Pico uses: http://www.modelektronik.com/download/upd7759.pdf It's emulated in MAME, so it should be a snap to support. If you need timings, the blue thing to the left...
- Sat Apr 21, 2007 1:18 am
- Forum: Sound
- Topic: ym2612 vs ym2610
- Replies: 3
- Views: 7965
It's a little confusing: YM2610 has 4 channels FM, 3 channels SSG, and 2 types of ADPCM YM2610B has 6 channels FM, 3 channels SSG, and 2 types of ADPCM YM2612 has 6 channels FM, no SSG, no ADPCM (but a DAC instead) You can still apply SSG-type envelopes to the FM channels on the YM2612. The Neo*Geo ...