SpritesMind.Net

If you are developing a game, what are you going to do: use the 100% of the cpu just to wait for the correct scanline?
A smart solution, proposed by other members, is to use the h exception of the previous line and then check for the wanted line on the counter.


Dont worry, this is just a timing ...

after polling the hv counter i achieved to dma 16 colors on only 1 hscan removing the garbage.
it's basically the same code. Im trying to do some improvements because the synchronization does not work if the console is overclocked.

You can test the rom here. I would apreciate if someone test this ...

Hi again spritesmind users.

After watching this video and seeing this can be achieved, https://www.youtube.com/watch?v=nt-AxAqlrOo i was trying to replicate the scrolling floor effect. So i decided to debug that level in regen emulator. After a few minutes i discovered that the game does not use ...

Thank you for your answers!

This is talked about in the Software Guidelines, section 3. The first thing is to always wait on the BUSY bit for the DMA after a reset. Even that isn't guaranteed to solve the issue if the reset occurred at a specific point in the bus grant handshake while starting a DMA. To solve that case, you ...

Also something that is at the very least possible, is trying to wait for Z80 to stop when its not in a correct state, I remember getting this issue frequently when ROMs do not properly reset/initialize

Actually i do not initialize z80 in any of my roms. And only this one has this effect.


A ...

Hi again to everyone.

I know i'm not a really active member of this community. But i would like to converse about a bug that i found at one of my roms.

This bug just consists that the console freezes after pressing the reset button several times very fast. Then sometimes the console completely ...

Really thank you for your fast and clear answer. Now i fully understand how to use that register.

Hi spritesmind users.

i have searched for some documentation about z80 bank register. Because i'm implementing my own z80 sound driver.

After reading this helpfull document https://emu-docs.org/Genesis/gen-hw.txt i found that i only have to write one by one the 9 high bits of my window direction ...

315-5433 in the IO+bus management chip. VDP is the other chip (315-5313 / 5313A / 5313A-01)

You'r right. Post Fixed.

https://s4.postimg.org/7m6juaggt/photo_2017-04-27_17-37-30.jpg

This is the only error i get on my megadrive. Sometimes the video looses syncs so my screen turns off and i cant see any. Sometimes the demo looks fine. But that robots seems to be corrupt on every test

Tested on
PAL-B(VE)
nº 1061-07 ...

Thank you all for you help. It really helped me to think back to my first code and fix it.

Finally the error was fixed after rewritten A LOT of ugly n00bish code. Probably there were something wrong at my very beginning lines because i had not really good idea of how to program this machine. I ...

I aligned the size to exactly 131.072 bytes (128kbs), blocked interrupts, and rewritted the DMA function so now it's much faster. It's almost a copy from the DMA function that you can find at this website.
http://www.hacking-cult.org/?r/18/25

Unfortunately the problem persists. 100% the same ...

Here's the rom
https://ufile.io/56a7

I'm pretty sure that is my fault. Probably i'm missing something on my DMA function that causes this failure on different cartidges, because other homebrew works fine on myfriends MegaDrive.

Also i tested it on another system.
MegaDrive 2 -> MK-1631-50 ...

Mine is :Megadrive 1 PAL-B(VE) 1601-07 <-- Works fine

Friend's :Megadrive 1 PAL-G 1601-18 <-- Glitchy DMA