Search found 824 matches

by Eke
Sun Jul 09, 2017 8:06 pm
Forum: Controls
Topic: Mega Mouse Usage
Replies: 23
Views: 4429

Re: Mega Mouse Usage

Thanks for this quick test. And yes, it's just a one shot write sequence , it's not supposed to update itself. Results are interesting but definitively not what is expected from games (and quite different from what you get in emulators). I suspect the reason is I'm switching TR output too fast for t...
by Eke
Sun Jul 09, 2017 12:36 pm
Forum: Controls
Topic: Mega Mouse Usage
Replies: 23
Views: 4429

Re: Mega Mouse Usage

Sorry to bump this thread but anyone here having a Sega/Mega Mouse could test this ROM on hardware (with mouse controller plugged in port 2) and report output values ? I'm trying to figure the acknowledge latency of the mouse protocol, as it seems to be (involuntarily ?) needed by a few game routines.
by Eke
Fri Jun 23, 2017 1:10 pm
Forum: Hardware
Topic: HDD (or flash) instead of a CD, questions...
Replies: 140
Views: 33386

Re: HDD (or flash) instead of a CD, questions...

It's not exactly the same (it push Q first, not P) but i think I got it know, based on previous post Beware that this last diagram is about different signals (SQCK/SQDT)- also present on CXD2500 chip (the latter is just named SQSO) - which are dedicated to Q-channel (with CRC verification): that wa...
by Eke
Tue Jun 20, 2017 12:08 pm
Forum: Mega/SegaCD
Topic: Subcodes only for CD+G ?
Replies: 8
Views: 1785

Re: Subcodes only for CD+G ?

If the SBSO line is flat, it won't bug the game ? It shouldn't affect software since, from my testing in emulator, neither games or BIOS care if the subcode interrupt never occurs But it's possible it could lock the ASIC and thus the whole Mega CD hardware, depending how it was designed. Quite unli...
by Eke
Mon Jun 19, 2017 9:17 pm
Forum: Mega/SegaCD
Topic: Subcodes only for CD+G ?
Replies: 8
Views: 1785

Re: Subcodes only for CD+G ?

D/M status, TOC and current Track infos are all retrieved/computed by dedicated 4-bit microprocessor using subcode Q data output by CD DSP on SUBQ pin (controlled by serial clock on SQCK pin). D/M status bit is found in Q subchannel control field while TOC and current Track infos are found in q-data...
by Eke
Mon Jun 19, 2017 7:43 pm
Forum: Hardware
Topic: HDD (or flash) instead of a CD, questions...
Replies: 140
Views: 33386

Re: HDD (or flash) instead of a CD, questions...

I wonder why they didn't do the same for the data : SDATA is sent what ever is D/M to the LC8951x Because that's the only way software can access sector data from the CD. This might not seem really useful for CD audio data but internal CD player for example uses it to display VU meter while playing...
by Eke
Tue May 02, 2017 12:50 pm
Forum: Video Display Processor
Topic: Titan's Mega Drive tech docs including Debug Register
Replies: 36
Views: 6476

Re: Titan's Mega Drive tech docs including Debug Register

Are you preserving the list of sprites determined to be on the current line when you do the re-fetch (sounds like maybe that's what you are doing, but it's not 100% clear)? Correct rendering relies on sprites showing on a line based on the old Y value even though the new Y value would cause them to...
by Eke
Sun Apr 30, 2017 7:55 am
Forum: Video Display Processor
Topic: Titan's Mega Drive tech docs including Debug Register
Replies: 36
Views: 6476

Re: Titan's Mega Drive tech docs including Debug Register

No idea what causes the vertical stripes in the 3rd pic, though, incorrectly emulated illegal plane modes maybe? BlastEm had these too and I believe fixing that is what got rid of them. Yes,that was it. Genesis Plus correctly emulated all illegal plane sizes except two ("10 10" and "10 11" in above...
by Eke
Sat Apr 29, 2017 12:07 pm
Forum: Video Display Processor
Topic: Titan's Mega Drive tech docs including Debug Register
Replies: 36
Views: 6476

Re: Titan's Mega Drive tech docs including Debug Register

Kabuto wrote: This looks like you still need to invert address bit 0 after converting the target address for 128k mode emulation.
Off course you are right, totally forgot about that. The textured cubes scene also look much less broken now...
overdrive-6-2.jpg
overdrive-6-2.jpg (19.68 KiB) Viewed 1765 times
overdrive-6-1.jpg
overdrive-6-1.jpg (20.26 KiB) Viewed 1765 times
overdrive-6-3.jpg
overdrive-6-3.jpg (19.07 KiB) Viewed 1765 times
by Eke
Sat Apr 29, 2017 8:03 am
Forum: Video Display Processor
Topic: Titan's Mega Drive tech docs including Debug Register
Replies: 36
Views: 6476

Re: Titan's Mega Drive tech docs including Debug Register

1) no per column vscroll changes here, just per rasterline vscroll changes in the zoomer, no vscroll changes at all when it twists Strange. This is what I got, not sure where this comes from . overdrive-1.jpg Also got similar weird vertical jitter on those voronoi circles overdrive-8.jpg 4) we call...
by Eke
Tue Apr 25, 2017 8:28 am
Forum: Video Display Processor
Topic: Titan's Mega Drive tech docs including Debug Register
Replies: 36
Views: 6476

Re: Titan's Mega Drive tech docs including Debug Register

This sounds like you're not treating transparent sprite pixels correctly, this effect uses sprites with palette 3, so their transparent pixels will be written to the linebuffer as 0x30. Yes, this was indeed the case: as mentioned in my previous post, transparent sprite pixels were never rendered in...
by Eke
Mon Apr 24, 2017 12:06 pm
Forum: Video Display Processor
Topic: Titan's Mega Drive tech docs including Debug Register
Replies: 36
Views: 6476

Re: Titan's Mega Drive tech docs including Debug Register

From what I could tell, background color was set to color 0 so result would be the same. I think the background is never displayed anyway if bit 7 or bit 8 is set (or maybe only during x/y borders in case sprite layer is the one being forced active, I don't know, the doc is not 100% clear about that...
by Eke
Mon Apr 24, 2017 9:24 am
Forum: Video Display Processor
Topic: Titan's Mega Drive tech docs including Debug Register
Replies: 36
Views: 6476

Re: Titan's Mega Drive tech docs including Debug Register

Thanks again, I have another question regarding the debug mode when sprite plane is forced active (bits 8,7 = 0,1) : what happens for pixels where there hasn't been any sprite pixel (transparent or not) rendered in the line buffer ? The sprite buffer pixel color value is normally 0 in this case (sam...
by Eke
Sat Apr 22, 2017 8:14 am
Forum: Video Display Processor
Topic: Titan's Mega Drive tech docs including Debug Register
Replies: 36
Views: 6476

Re: Titan's Mega Drive tech docs including Debug Register

When bit 9 is set: 1) Make all four PSG channels always high (like when we use them for PCM) 2) Make their attenuation the same as for the channel selected by bits 11-10 That's all there's to it, really. You could do the PCM trick on them but 4x as loud (at the expense of no normal PSG output). Tha...
by Eke
Sat Apr 22, 2017 7:45 am
Forum: Sound
Topic: too many YM2612 infos ?
Replies: 14
Views: 1705

Re: too many YM2612 infos ?

Having a sub forum for YM2612 dedicated topics is a good idea but seems like a hard task to initialize and maintain. Each subthread should start with a post summarizing the current 'verified' informations we have on that part of the chip and kept updated according to the following thread discussion....