Search found 256 matches

by tomaitheous
Wed May 07, 2008 3:26 am
Forum: Megadrive/Genesis
Topic: 2gen header
Replies: 77
Views: 32035

but why the cart doesn't die if MD wanted to read it ? Well, this is X3 for SFC. The security chip would detect longer than normal (whatever that is) linear reads from the cart pins. If detected then it would fry itself. The trick was to read smaller chunks, then read from random addresses, then go...
by tomaitheous
Wed May 07, 2008 1:03 am
Forum: Demos
Topic: Unfinished platform game
Replies: 34
Views: 20714

Shiru: thanks for the link. I see he did that effect in the video :)
by tomaitheous
Wed May 07, 2008 12:57 am
Forum: Megadrive/Genesis
Topic: 2gen header
Replies: 77
Views: 32035

You need to do something really wrong to destroy the cartridge that way, just feed the extra HW the data it wants and you're done. The worst that can happen is a bad dump honestly (or the deletion of the data in SRAM) :/ No, the cartridge had a copy protection mechanism. If you tried to read from t...
by tomaitheous
Tue May 06, 2008 5:56 am
Forum: Megadrive/Genesis
Topic: 2gen header
Replies: 77
Views: 32035

Sik wrote: It would be enabled by just writing something with the 68k. A copier is never capable of doing this, so making it dump-proof. You would need to modify your copier to be able to dump the ROM.
Or worse - it could destroy the rom. Megaman X3 had this problem iirc.
by tomaitheous
Tue May 06, 2008 4:54 am
Forum: Demos
Topic: Unfinished platform game
Replies: 34
Views: 20714

Cinco de mayo release? :D

Shiru: I have a question about the music. One of the instruments (lead) sounds like you have a low-pass filter that you're adjusting up and down as the instrument plays. How did you achieve that on the 2612!?
by tomaitheous
Tue May 06, 2008 4:50 am
Forum: Blabla
Topic: yamaha 2612 chip
Replies: 3
Views: 4201

Oh that's embarrassing- right there on the wiki site. Thanks HW.
by tomaitheous
Tue May 06, 2008 3:47 am
Forum: Sound
Topic: Dramatic bad DAC output quality !
Replies: 60
Views: 29595

Sik wrote: PWM waveforms are way more distorted >_>
PWM relies on a filter and a really fast frequency output. Some CD players supposedly use it. Both of the GBA's channels are actually PWM (even though it takes a binary value for a sample). The PWM unit outputs 1bit waveforms at 16mhz.
by tomaitheous
Tue May 06, 2008 3:41 am
Forum: Blabla
Topic: yamaha 2612 chip
Replies: 3
Views: 4201

yamaha 2612 chip

Not sure if this is the right place for this question (again :) ).

Anyone have the pin out for the 2612 chip? I'm removing it from one of my model 1 systems and would like to interface it with another controller/MCU.
by tomaitheous
Mon May 05, 2008 11:38 pm
Forum: Sound
Topic: Dramatic bad DAC output quality !
Replies: 60
Views: 29595

That distortion is caused by one thing called leakage, value written to DAC will go silence in a short period of time... on emulator it doesn't happen that's why speech sounds better... on real HW instrument like cymbals sound a bit better because of this. I take it you're referring to "return to z...
by tomaitheous
Mon May 05, 2008 4:41 am
Forum: Sound
Topic: Dramatic bad DAC output quality !
Replies: 60
Views: 29595

The only thing I can think of is the response time of the YM chip for the DAC write. I've read that two fast of writes to the DAC will be ignored. Some external chips have a way of slightly delaying a processor when it writes to a port (not sure of the 68k has something similar to /RDY). It's possib...
by tomaitheous
Fri May 02, 2008 2:34 pm
Forum: Sound
Topic: how can i do music on megadrive?
Replies: 288
Views: 326740

A byte really isn't enough for a decent instrument sample. I used a word when I did some MIDI instruments on the Amiga. Most of my instruments weren't 64K long, but most WERE longer than 256 bytes. You probably could do some really simple instruments in 256 bytes, though. no no, I mean the upper by...
by tomaitheous
Fri May 02, 2008 4:02 am
Forum: Sound
Topic: how can i do music on megadrive?
Replies: 288
Views: 326740

Why is there a need for such thing ? Additional timing ? Oh - just for frequency scaling. One way is to use two bytes. The low byte acts as the float part and the upper byte is the whole part. Just add the whole part/byte to the wave/sample pointer. That way you don't have to store multiple samples...
by tomaitheous
Wed Apr 30, 2008 2:45 am
Forum: Sound
Topic: how can i do music on megadrive?
Replies: 288
Views: 326740

2 year old topic.... so many memories.... I wrestled with 6KHz 2Ch playback code and now I have (or had) 56KHz 2Ch code, plus music and sound effects !!! I said "I will I will", and I now, I've done it !!! (it took quite some time though). I feel good :) TmEE: Hey - do you have enough cycles left o...
by tomaitheous
Wed Apr 30, 2008 2:38 am
Forum: Tools
Topic: Interest in High Level Scripting Language for Sega CD Dev?
Replies: 11
Views: 9663

Hmm, I like the idea. I've actually been considering the possibility of a SCUMM-style system for Sega CD - would this be something similar, or would it be more low-level? There is already a SCUMM interpreter for the SegaCD - it's running Monkey Island :wink: I did some little work on the TGCD Loom ...
by tomaitheous
Sun Apr 27, 2008 3:48 am
Forum: Blabla
Topic: Yamaha internal waveform info
Replies: 17
Views: 13227

Thanks for the sample grabs TmEE :D What was the output of the carrier set to? Also, that's a much higher resolution than I was expecting.