Search found 2419 matches

by TmEE co.(TM)
Wed Jul 28, 2021 5:18 pm
Forum: Megadrive/Genesis
Topic: TMSS
Replies: 4
Views: 164

Re: TMSS

The SEGA write existed before TMSS ROM did, though it became actually functional with the introduction of TMSS with VA5/6 MD1 hardware. It was part of a copyright thing that all ROMs must have in them prior to introduction of the TMSS ROM which did its own verification on top while retaining the stu...
by TmEE co.(TM)
Mon Jul 26, 2021 7:25 pm
Forum: Megadrive/Genesis
Topic: TMSS
Replies: 4
Views: 164

Re: TMSS

Not doing the SEGA write results in VDP not cooperating with you on hardware that requires this write and that's what the version register will tell you if it is necessary to do so. The value is hardcoded in the ASIC and cannot be influenced by normal means, there's only 0000 and 0001 in all the exi...
by TmEE co.(TM)
Mon Jul 12, 2021 4:03 am
Forum: Megadrive/Genesis
Topic: VRAM write macro $3FFF mask
Replies: 3
Views: 261

Re: VRAM write macro $3FFF mask

This stems from TMS99xx and SMS VDPs, which only had 16bit command words with 16KB VRAM. MD VDP extended the command words to 32bits and the new address bits (and few extra things) are in the second part, while first part is kept like the older stuff. There's some playroom with how you arrange the b...
by TmEE co.(TM)
Mon Jun 28, 2021 11:04 am
Forum: Megadrive/Genesis
Topic: Problem getting animation working on Sega Genesis.
Replies: 2
Views: 426

Re: Problem getting animation working on Sega Genesis.

It is quite possible your frame is so large that it overwrites non-graphics parts in the VRAM, such as tilemaps or some other things that must coexist there along with the tiles themselves.
by TmEE co.(TM)
Fri Apr 09, 2021 9:59 am
Forum: Megadrive/Genesis
Topic: VDP FIFO and DMA questions
Replies: 3
Views: 1916

Re: VDP FIFO and DMA questions

Half lines are part of the video signal, around VSYNC signal. They existed to allow early sync separation circuits to reliably produce a VSYNC pulse using a simple integrator circuit on extracted CSYNC signal. Two halflines make a whole line. The 16 and 17 are Hsync length in the half lines, un pixe...
by TmEE co.(TM)
Fri Apr 09, 2021 3:25 am
Forum: Megadrive/Genesis
Topic: VDP FIFO and DMA questions
Replies: 3
Views: 1916

Re: VDP FIFO and DMA questions

Here is all there is to know about MD video output timings, from my unreleased MD VDP doc. Things are not fully finished around half lines parts, the number lines mean pixels counts during half lines, one number while in sync period, other outside sync. 888aaa999 ones mean pixel patterns during sync...
by TmEE co.(TM)
Sat Apr 03, 2021 10:56 pm
Forum: Super 32X
Topic: Reset and VRES
Replies: 2
Views: 1435

Re: Reset and VRES

I imagine you modify stack to have a new return address prior to exiting the interrupt and probably force caches to be flushed too.
by TmEE co.(TM)
Thu Mar 25, 2021 8:37 am
Forum: Super 32X
Topic: Questions on emulating the 32X
Replies: 14
Views: 2754

Re: Questions on emulating the 32X

Is this the case only when it's the backdrop color (no background/sprites), or when it's the backdrop color OR palette color 0 (from a background or sprite)? VDP never renders color 0 of any palette when drawing BGs and sprites on the screen, it is the backdrop color that is output when a particula...
by TmEE co.(TM)
Wed Mar 24, 2021 10:38 am
Forum: Super 32X
Topic: Questions on emulating the 32X
Replies: 14
Views: 2754

Re: Questions on emulating the 32X

VDP outputs a signal called !YS which is active when nothing/backdrop color is being output, it is present on cartslot along with !HSYNC and !VSYNC signals and 32X uses them for image alignment and composition purposes. There are 3 signals involved in controlling if 32X or MD RGB signal is switched ...
by TmEE co.(TM)
Tue Feb 16, 2021 7:53 pm
Forum: Megadrive/Genesis
Topic: Version Register
Replies: 6
Views: 1846

Re: Version Register

I have only ever seen the chip in Japanese machines, never in EU or US ones. I have the chip transplanted onto an EU VA5/6 board and the region mod changes TMSS behaviour. l_oliveira has some observations done too in past, telling that "SEGA" write is unnecessary when the language setting is in JP i...
by TmEE co.(TM)
Tue Feb 16, 2021 11:48 am
Forum: Megadrive/Genesis
Topic: Version Register
Replies: 6
Views: 1846

Re: Version Register

Right, 315-5402 is special, it shows no TMSS when in JP mode, while TMSS is shown in EN mode. I did notice the freezing problem with TMSS as I tried to dump the ROM when accessing the banking register...

The value is not adjustable externally.
by TmEE co.(TM)
Mon Feb 15, 2021 7:46 pm
Forum: Megadrive/Genesis
Topic: Version Register
Replies: 6
Views: 1846

Re: Version Register

Verison part is hardwired to 0001 on all hardware I have seen (that has TMSS)
by TmEE co.(TM)
Tue Jan 12, 2021 10:51 am
Forum: Megadrive/Genesis
Topic: Discrepency in TMSS ROM Dumps?
Replies: 5
Views: 2140

Re: Discrepency in TMSS ROM Dumps?

Amstrad uses 315-5476 ASIC which has the same TMSS in it as all the other MD2s. Teradrive is the only special one.
by TmEE co.(TM)
Mon Jan 11, 2021 8:11 pm
Forum: Megadrive/Genesis
Topic: Discrepency in TMSS ROM Dumps?
Replies: 5
Views: 2140

Re: Discrepency in TMSS ROM Dumps?

All the TMSS dumps I have done from various chips gave same file that already lingers on the internet. I have not had a chance to try to dump things from VA2 MD2s and I have not tried to dump Genesis3 VA2. MD2 VA4 and Genesis3 VA1 I think I have dumped but I am not sure, it has been 10 years by now ...
by TmEE co.(TM)
Sun Nov 29, 2020 8:06 am
Forum: Megadrive/Genesis
Topic: Megadrive ASIA Configuration
Replies: 2
Views: 2450

Re: Megadrive ASIA Configuration

50Hz + ENG, same as European models.