Search found 208 matches

by mickagame
Thu May 26, 2016 12:26 pm
Forum: Video Display Processor
Topic: VDP VRAM access timing
Replies: 36
Views: 14739

Re: VDP VRAM access timing

If i undst good the shema from Nemesis : Slot 12 : When Hsync go high the line start to be drawn on tv Slot 6 to 13 : The first left scrolled 2 cells are fetched and output to internal line buffer => During this period 2 cells fulling with background color are output to tv (left border) Slot 14 to 2...
by mickagame
Sun May 08, 2016 5:34 pm
Forum: Megadrive/Genesis
Topic: Genesis Vdp Global Documentation
Replies: 2
Views: 1037

Re: Genesis Vdp Global Documentation

Thanks for the links ;-)
by mickagame
Sat May 07, 2016 8:49 am
Forum: Megadrive/Genesis
Topic: DMA and FIFO
Replies: 4
Views: 1048

Re: DMA and FIFO

Thanks for your answer.
Does the latency affect the dtack signal from vdp to 68K when perform a read or write operation?
by mickagame
Fri May 06, 2016 3:50 pm
Forum: Megadrive/Genesis
Topic: DMA and FIFO
Replies: 4
Views: 1048

DMA and FIFO

Does The DMA is using the external access slot to transfert data from/to vram?
What happen for example if there is a dma fill or dma copy and the 68k try to access vram?
by mickagame
Wed May 04, 2016 12:33 pm
Forum: Megadrive/Genesis
Topic: Genesis Vdp Global Documentation
Replies: 2
Views: 1037

Genesis Vdp Global Documentation

I would like to know if exist a documentation compiling all informations about the genesis vdp (description of all slot, register latch timing, interrupt timing ...).
by mickagame
Mon Jul 20, 2015 4:06 pm
Forum: Video Display Processor
Topic: VDP VRAM access timing
Replies: 36
Views: 14739

If i take your notes Nemesis. From Access Slot 6 to 13 (2 cells Border) datas from 2 first displayed cells are latched and renderer in a 2 cells buffer. During Access Clots 14 to 21 (2 first displayed cells) pixels are generated from the buffer and during this time datas from displayed cells 3 and 4...
by mickagame
Tue Jul 14, 2015 9:20 pm
Forum: Exodus
Topic: Exodus 2.0 + Open Source Release
Replies: 105
Views: 16734

Hi Nemesis. The debugger of Exodus is very useful to me to program my emulator. Tanks to your work.
by mickagame
Mon Jul 13, 2015 10:51 am
Forum: Megadrive/Genesis
Topic: Question About Sonic 2
Replies: 4
Views: 820

All works OK now thanks for your help ;-)
by mickagame
Sat Jul 11, 2015 6:11 am
Forum: Megadrive/Genesis
Topic: Question About Sonic 2
Replies: 4
Views: 820

Thanks for your answer. I would like to understand the utility of Z80 interrupt that is asserted every frame durng one line.
Perhaps this is noob question but i'm sjust starting adding audio part in my emulator.
by mickagame
Fri Jul 10, 2015 4:38 pm
Forum: Megadrive/Genesis
Topic: Question About Sonic 2
Replies: 4
Views: 820

Question About Sonic 2

Does anyone knows if Sonic 2 Z80 access M68K memory via bank space mecanism? Or all datas are loaded in Z80 Memory?

I'm currently testing The Z80 part in my emulator.
Does exist some Z80 test rom?
by mickagame
Fri Jun 26, 2015 6:49 pm
Forum: Exodus
Topic: Exodus 2.0 + Open Source Release
Replies: 105
Views: 16734

Hi Nemesis.
Super Street Fighter 2 show a red screen at start.
Does Exodus can support it?
by mickagame
Sun Jun 07, 2015 6:34 pm
Forum: Hardware
Topic: I/O Ports read upper byte
Replies: 1
Views: 1591

I/O Ports read upper byte

Does anyone knows what happens when reading higher byte of I/O ports?
In doc they said that in case of byte access only lower byte is meaningful (mean odd adress).
by mickagame
Fri May 29, 2015 1:02 pm
Forum: Hardware
Topic: Does Memory Chip have endianness?
Replies: 3
Views: 1747

I think whatever th access m68000 do (word or byte) the 68000 always do word access. Lds and uds complete the access. In exemple i take the m68000 do word access and because uds is set (access to addr 0x000000 so msb) the CPU takes only thé msb of the word and put in register. That s my point of vie...
by mickagame
Fri May 29, 2015 6:16 am
Forum: Hardware
Topic: Does Memory Chip have endianness?
Replies: 3
Views: 1747

Does Memory Chip have endianness?

Writing my genesis emulator i'm asking myself question about memory Chip. Does a memory chip is made to take part or in MSB or LSB system? If i take the example of M68000. If I write 0x1100 at 0x000000, the processor waiting that : - If I read data at 0x000000 it return 0x11 (MSB) - If I read data a...
by mickagame
Tue May 26, 2015 7:51 pm
Forum: Video Display Processor
Topic: Understanding VDP
Replies: 10
Views: 1801

It make sens !!!