Search found 2441 matches
- Mon Jun 22, 2020 5:49 pm
- Forum: Megadrive/Genesis
- Topic: Most compatible way to jump to game image on hardware - making my own cart
- Replies: 21
- Views: 31414
Re: Most compatible way to jump to game image on hardware - making my own cart
You could see what TMSS itself does when starting a game : http://www.tmeeco.eu/SMD/TMSSCODE.ASM
- Sun Jun 21, 2020 9:02 pm
- Forum: Sound
- Topic: YM2612 & distorted sound output
- Replies: 7
- Views: 11968
Re: YM2612 & distorted sound output
The output is a pulsetrain, with YMCLK / 144 clocks per sample and 24 clocks per pulse (with differing duty cycle and amplitude for 3438 and 2612). There's harmonic content going into MHz range in there so you need fairly good opamps to deal with it effectively. The output is also very weak and shou...
- Sun Jun 14, 2020 4:17 pm
- Forum: Sound
- Topic: YM2612 & distorted sound output
- Replies: 7
- Views: 11968
Re: YM2612 & distorted sound output
YM2612 and YM3438 have pulse train based outputs where all channels are sent sequentially. On 2612 the pulses are very narrow and also have fairly low amplitude while 3438 has much wider and bigger pulses, allowing for better SNR. What you see on your scope is mainly due to aliasing, when you up the...
- Sun May 17, 2020 11:30 am
- Forum: Megadrive/Genesis
- Topic: VDP 8x16 Interlace Mode
- Replies: 7
- Views: 10968
Re: VDP 8x16 Interlace Mode
Possibly but these are buried into past that is many years ago...
- Fri May 15, 2020 10:41 am
- Forum: Megadrive/Genesis
- Topic: VDP 8x16 Interlace Mode
- Replies: 7
- Views: 10968
Re: VDP 8x16 Interlace Mode
It is good for still images, you see markedly higher detail. When things begin to move there will be various interlacing related artifacts appearing.
Here's couple experiments I made a while ago :
http://www.tmeeco.eu/SMD/HIRES.BIN
http://www.tmeeco.eu/SMD/INTERLAC.BIN
Here's couple experiments I made a while ago :
http://www.tmeeco.eu/SMD/HIRES.BIN
http://www.tmeeco.eu/SMD/INTERLAC.BIN
- Thu Apr 30, 2020 9:39 am
- Forum: Sound
- Topic: SN76489 polarity
- Replies: 4
- Views: 9898
Re: SN76489 polarity
There's no negative polarity on TI/VDP PSG and most other PSG type sound chips. You do get stuff settle below ground level when you highpass filter the final chip output as it is done on all hardware outside the sound chip itself. On the TI/VDP PSG, outputs start high and toggle between 0 and a high...
- Sun Mar 08, 2020 11:09 pm
- Forum: Mega/SegaCD
- Topic: Best solution for anime VisualNovel
- Replies: 3
- Views: 14717
Re: Best solution for anime VisualNovel
When you play CDDA you lose access to the CD drive more or less so whatever you want to show will have to fit in the RAM, and you have limited amount of that.
- Thu Jan 30, 2020 11:23 am
- Forum: Cartridge
- Topic: Designing MD sdcard flashcart for fun, advice?
- Replies: 37
- Views: 55935
Re: Designing MD sdcard flashcart for fun, advice?
I guess it'll work then, I hope there won't be more troubles with the new version ~
- Thu Jan 30, 2020 2:45 am
- Forum: Cartridge
- Topic: Designing MD sdcard flashcart for fun, advice?
- Replies: 37
- Views: 55935
Re: Designing MD sdcard flashcart for fun, advice?
I think it would work, assuming flash is fine with its !CE always low. Logic itself should be sound, disregarding any timing issues.
- Thu Jan 16, 2020 12:34 pm
- Forum: Hardware
- Topic: Cartridge slot questions
- Replies: 23
- Views: 67883
Re: Cartridge slot questions
MD2 VA0 and VA1 do not have 75ohm load on the cartslot signals. 32X just has very low output impedance amp that can drive headphones (i.e 16 ohm load), there's no variation in output level due to it. You just need a beefy amp to make things work.
- Thu Jan 16, 2020 10:29 am
- Forum: Hardware
- Topic: Cartridge slot questions
- Replies: 23
- Views: 67883
- Thu Jan 16, 2020 12:25 am
- Forum: Hardware
- Topic: Cartridge slot questions
- Replies: 23
- Views: 67883
Re: Cartridge slot questions
The clipping is due to the mixing+amp chip, it isn't rail-to-rail IO capable (but it can get very close to ground due to special design, with top side being typical ~1V shy from a power rail) and due to it there will be early clipping. If the attenuated and filtered PWM signal was given a DC offset ...
- Wed Jan 15, 2020 5:43 pm
- Forum: Hardware
- Topic: Cartridge slot questions
- Replies: 23
- Views: 67883
Re: Cartridge slot questions
I have not seen the edit, I was waiting for a new post lol. I'll do measurements soon. 32X audio output is almost 4Vpp on the cartslot pins, and it clips early, both tips of the sine are flat. There's a 45Hz -3db point high pass filter forming in most MDs (47µF cap in 32X, 75ohm load on most MDs). A...
- Fri Jan 10, 2020 4:19 am
- Forum: Cartridge
- Topic: Designing MD sdcard flashcart for fun, advice?
- Replies: 37
- Views: 55935
Re: Designing MD sdcard flashcart for fun, advice?
That is a pretty nice writeup ~
- Thu Jan 09, 2020 9:37 am
- Forum: Hardware
- Topic: Cartridge slot questions
- Replies: 23
- Views: 67883
Re: Cartridge slot questions
Someone make me a 32X test ROM with same sort of grayscale ramp as seen here : viewtopic.php?f=22&t=2188
And while at it, play a full scale sinewave on both L and R side, I'll get the scope out and measure the levels at various points.
And while at it, play a full scale sinewave on both L and R side, I'll get the scope out and measure the levels at various points.