Search found 434 matches

by ob1
Thu Dec 28, 2006 2:42 pm
Forum: Video Display Processor
Topic: 512 colors demo
Replies: 21
Views: 11461

Ok I got it working. It displays ... 256 colors.
Not so bad.
I'm beginning to feel bored.
Guess it's time for a change ...
by ob1
Thu Dec 28, 2006 1:26 pm
Forum: Video Display Processor
Topic: 512 colors demo
Replies: 21
Views: 11461

Wel wel well... I've manage to do DMA while HBL. Couldn't figure out why it wouldn't run sooner. But I can't get the 512 colors ... The best I have is a multi-colored blanking screen Fifty-fifty... I've tried to do DMA from VRAM to CRAM move.l #$C00000C0,GFX_CTRL ; Trigger DMA to CRAM 0x0000 , and i...
by ob1
Thu Dec 28, 2006 9:34 am
Forum: Video Display Processor
Topic: 512 colors demo
Replies: 21
Views: 11461

It looks as if I was doing bad my DMA to CRAM. Afeter the DMA to CRAM, I can't make any DMA again.
Charles MacDonald points
When doing a transfer to CRAM, the operation is aborted once the address register is larger than 7Fh.
The problem wouldn't be in HBL, but in my DMA.
by ob1
Wed Dec 27, 2006 5:44 pm
Forum: Video Display Processor
Topic: 512 colors demo
Replies: 21
Views: 11461

It's 64 words long. Much more than the transfer quantity of 16 as specified in the Sega Genesis Technical Overview. Do I try to DMA too much ?
All my instructions take 120 cycles. Much more than the 36 CPU cycles of the same doc. Are my settings too slow ?
by ob1
Wed Dec 27, 2006 5:37 pm
Forum: Video Display Processor
Topic: 512 colors demo
Replies: 21
Views: 11461

You'll find the whole code on my site :
http://perso.wanadoo.fr/olivier.brosseron/PAL512.ASM

It looks as if after the first DMA, I can't make it anymore.

Thank for interest.
by ob1
Wed Dec 27, 2006 11:00 am
Forum: Video Display Processor
Topic: 512 colors demo
Replies: 21
Views: 11461

512 colors demo

Damned ! I try hard to run a 512 colors demo, but can't manage to do it. I've read the TmEE 960 demo, but didn't figure out how to use it. So, here are my datas. I have 16 tiles, from 00000000 ... 00000000 to FFFFFFFF ... FFFFFFFF. I store it in VRAM 0x0000 I have 512 colors, from 0000, 0002, 0004 ....
by ob1
Mon Dec 18, 2006 1:03 pm
Forum: Megadrive/Genesis
Topic: Sega2.doc is enough, Really?
Replies: 23
Views: 14178

In his Sega Genesis VDP Documentation, Charles MacDonald says
"The name table size cannot exceed 8192 bytes, so while a 64x64 or 128x32 name table
is allowed, a size of 128x128 or 64x128 is invalid."
by ob1
Mon Dec 18, 2006 8:48 am
Forum: Megadrive/Genesis
Topic: Sega2.doc is enough, Really?
Replies: 23
Views: 14178

Stef wrote:...It can be sized from 32x32 to 128x128 (tile based)....
I thought the tile map ranges up to 128 x 32, 64 x 64 or 32 x 128.
by ob1
Fri Dec 15, 2006 2:55 pm
Forum: Megadrive/Genesis
Topic: Genny and 3D
Replies: 138
Views: 53737

stalepie wrote:Star Cruiser intro (Megadrive)
http://www.youtube.com/watch?v=MIMEfxYh3lc
Amazing !
by ob1
Fri Dec 15, 2006 2:44 pm
Forum: Megadrive/Genesis
Topic: Sega2.doc is enough, Really?
Replies: 23
Views: 14178

TmEE co.(TM) wrote:... x86(used in PCs) sucks compared to it[68k]...
... oulà ... 68k ISA is as CISCy as x86 ... Although I largely prefer 68k to x86 too ! What about 32 bits RISC (SH2, ARM7, ...) ?

OK we're off focus.

We'll made this ISA debate much later.
by ob1
Fri Dec 15, 2006 12:42 pm
Forum: Megadrive/Genesis
Topic: Sega2.doc is enough, Really?
Replies: 23
Views: 14178

Actually, I don't find the 68k especially hard to develop. Moreover, it's more what we're used to, with registers, whereas the 6502 only has accumulator (think Z80 ?). OK, the 6502 has 3 index registers. The video display processor (VDP) is sure a little bit tricky to program, but once you've figure...
by ob1
Fri Dec 15, 2006 10:27 am
Forum: Megadrive/Genesis
Topic: Sega2.doc is enough, Really?
Replies: 23
Views: 14178

I quite disagree.
sega2.doc has been a valuable help for me, as the Sega Genesis VDP documentation by Charles McDonalds.
Can't remember exactly what was my main source, but these 2 docs helped me up to 2/3.

Please note that I don't use sound.
by ob1
Thu Dec 14, 2006 9:38 am
Forum: Megadrive/Genesis
Topic: MD disassemblies and source codes
Replies: 14
Views: 8211

http://sega-devega.net/assemblers.php

I'm beginning to miss this "files" section !
by ob1
Thu Dec 14, 2006 7:49 am
Forum: Megadrive/Genesis
Topic: MD disassemblies and source codes
Replies: 14
Views: 8211

It seems to _m_e that cdoty has a disassembler.
by ob1
Thu Dec 07, 2006 10:37 am
Forum: Megadrive/Genesis
Topic: Genny and 3D
Replies: 138
Views: 53737

Here we go with flat shading. 1- Transform vertices (3D points) into pixels (2D points) 2- get lines (step 1 needed) 3- transform lines into polygon (step 2 needed) 4- get 3D vectors 5- compute the normal to the vectors (step 4 needed) 6- get color from the normal (step 5 needed) 7- for all the poly...