SpritesMind.Net

thanks for the details... Now I have to understand how you define the power of the dummy load needed. In fine, I'll need a dummy load (high power) and a very small resistor to measure current. If you want to verify that the adapter can provide 10V at 1.2A: R = V / I = 10V / 1.2A = 8.3 ohms P = I*V ...

Thanks Charles. But is it really all that unprecedented? The open-source hardware movement is gathering momentum, and I can't help but think/hope that the days of "look at this cool thing I made but you can't have it cos it's mine all mine my precious etc etc" are coming to an end. :D Ah, I didn't ...

Incredibly cool! Thanks for sharing the entire project like this, it's sort of unprecedented. I can't wait to see what people do with it.

This is really great work. Thanks for sharing all the details and disassemblies too.

I have found the problem: register 0x0B was set to 1. Changing it to 3 solves the problem. Nevertheless, according to Charles MacDonald's VDP document, it should if the register is set to 1. So, this seems to be a mistake in that document. There's two line scrolling modes, 1 and 3. Mode 1 re-uses t...

I'd have thought it would be difficult since the YM2612 is the one FM chip that isn't AY8910/YM2149 compatible, almost all the others (YM2203, YM2610, YM2608, etc.) have AY8910/YM2149 PSG outputs. Maybe using the SSG-EG envelopes makes the FM channels sound more like AY channels, and that's the tric...

How much of bandwidth would I lose if I setup multiple DMA transfers? Does the setup and stopping of the DMA transfer on the hardware side take enough time to lose a non-trivial amount of bandwidth? When I was doing some FMV tests there was no appreciable change in speed between doing one huge tran...

r57shell wrote:That is what I doing now reading sources... and making own test rom.

Very interesting moment: Is it true for backdrop color too?

Luckily it only affects the sprites.

So color $0E of background layers or the backdrop appear as they should in shadow/highlight mode.

1) Is it true? 2) Where I can read mostly latest info about VDP research? forum/doc? Yes it's a side effect of how the highlight function works. Normally for sprites using palette 3, a sprite pixel value of $0E enables the highlight effect. Now for whatever reason, possibly a bug, a sprite pixel va...

Which is why I ask this question: would it even technically be possible, in theory, to design a cartridge PCB that permitted additional RAM that would be addressable (or at least bank switched somehow)? Mind you, I'm not seriously planning to sell a minecraft-type game for real hardware, but the id...

It just spins here, all the game code is called from the vblank interrupt. Doesn't this have a HUGE execution time cost in terms of wasted cycles? Isn't there more available time outside of vblank? The CPU isn't really restricted to processing within the V-Blank time (38 scanlines or so). Once the ...

Just made some corrections!

Wait, you're saying that the DMA transfers are in sync with VClk? doesn't make sense to me as they seem to pulse at 150/300ns... Ack, I had the wrong sampling mode (CPU clock instead of free running 500 MHz clock) selected on the logic analyzer. Thanks for pointing this out. I'll make a correction ...

For the address selection (which is what the ASEL is probably meant for judging by the name it bears) the RAS signal can be used most of the times to select the row/column of an external mux: Since drams typically need a row address hold time of about 10ns (or sometimes less), we can take advantage...

Been looking at the expansion port, tests done with the /CART pin grounded. (with corrections from Jorge Nuno) /ROM is asserted when reading/writing $400000-$5FFFFF. The Sega CD uses it as an output-enable strobe for the boot ROM, but it is a general chip select for any kind of access like /FDC. /RA...