SpritesMind.Net

Take z80 RAM contents on power up and do a Shift/XOR on a couple of addresses... I doubt TMSS clears the ZRam, so that could be a good seed. Or take advantage from the user like the time it takes him to press, hold and release the start button

Hum, Tiido said that one of the 68k RAMs is used in SMS mode. The one with the fantom address line: IA14. If this line is disconnected (to use the real VA14, SMS mode won't work anymore). So /NOE has to work somewhat for the z80. In MD mode, swapping IA14 for VA14 has no effect. But hey, I can give ...

Oh hi! Yes that was me. Im sorry for not posting this here, but I forgot SM had an entire section dedicated for demos... -___- *hides* As for the revision glitch I dunno. I ran it on my GenIII ang MD1 and they both run fine but with a difference: My GenIII doesnt suffer from the 2-Cell VScrolling bu...

Yes it must be something else, considering ROMs were around 100ns back then and these S-RAMS are 55.

I hope I get my holiday soon to do some work on my cart.

Thats a rough description, but the accurate signal timings and relationship with inputs and the current state is what its needed.

Even if the chip was readable, what would we do with with the jedec file? Is the internal physical layout known? « for porting into a more recent IC

So the only solution is to figure out what it does exactly and get a new replacement part. Good luck

Nope, SEL1 is about the 68000 clock. <- This is how I got the synchronous overclock "SEL1 I, Switches Clk1 direction: 0 = Mclk/7, 1 = I(nput);" [ http://wiki.megadrive.org/index.php?title=HardWare:VDPpinout ] The Pixel clock characteristics (and display mode) is got from the settings of reg C: http:...

I wish I saw this thread earlier to take some ideas into my cartridge :lol: : http://trapalhadas.no.sapo.pt/12112010083.jpg (sorry for the huge pic) Firmwares still very incomplete :cry: , but the features are: - Up to 16MB (maybe 32) of D-RAM (Minimum bank size = 256kbytes); - USB; - MicroSD slot; ...

Um... not the VA3, the first TMSS machine is the VA5 rev. "...modifications using standard components, at a total extra cost of approximately fifty cents." This could mean a regular 74HC chip, and indeed you can use an OR-gate (74HC32) connected to A23 and A22 and use the output as a rom chip select...

Instead of using just one magic address for extra-features enabling, you could use a method like flash memories use: they need a series of commands to be provided in the correct order for erasure operations.

CD5 is used on DMA transfers and fills, CD4 on VRAM copies, other command bits combinations aren't known.

Gens Kmod does Vram DMA logging to a file, and regen has breakpoints on Vram RW activity, so I think you have to use them both to handle DMAs and 68k writes .

At 8MHz, don't even bother with length equalizing, the lambda is more than 10 meters, so only worry if you have a wire length of 1 meter or more

Don't forget to add it!

BTW, I've made a nice VDP pinout pic:

http://wiki.megadrive.org/index.php/HardWare:VDPpinout

Using info from Charles's vdppin.txt, and from the megadrive schs (and from me)

Wrote the first version of the ASIC listing:
http://wiki.megadrive.org/index.php/Har ... _Sega_ASIC

I missed the "SEGA" Z80 (I don't know it's part number) , and the sega chip from VA2 MD2s