Search found 426 matches

by ob1
Wed Feb 24, 2021 2:07 pm
Forum: Megadrive/Genesis
Topic: palette loading problem (new to asm68K)
Replies: 1
Views: 47

Re: palette loading problem (new to asm68K)

Hello Cydeenwins.
Your code looks good, but since it states it starts at 0, I wonder if you put a valid header ...
by ob1
Tue Feb 23, 2021 4:56 pm
Forum: Super 32X
Topic: 32x "security code" reverse engineered
Replies: 26
Views: 17388

Re: 32x "security code" reverse engineered

OK I got it.
Quite new for me, but that explains a lot.
Thank you very much ^^
by ob1
Tue Feb 23, 2021 3:51 pm
Forum: Super 32X
Topic: 32x "security code" reverse engineered
Replies: 26
Views: 17388

Re: 32x "security code" reverse engineered

Hello @srg320, and thank you very much for you quick answer.
Are you telling me that the custom internal ROM ($00~$FF) is actually ... RAM ?
by ob1
Tue Feb 23, 2021 1:43 pm
Forum: Super 32X
Topic: 32x "security code" reverse engineered
Replies: 26
Views: 17388

Re: 32x "security code" reverse engineered

Sorry to relive a topic - again !, but there is one line of code that I find surprising. Just between SDER and TV Mode Check, we have move.l #$8802A2,$70 ; 21 FC 00 88 02 A2 00 70 If my 68k isn't too rusty, I translate this by "write the value 0x8802a2 ... in ROM ?!" First of all, how is it possible...
by ob1
Fri Feb 19, 2021 1:56 pm
Forum: Super 32X
Topic: Master SH2 BIOS
Replies: 12
Views: 8792

Re: Master SH2 BIOS

Sorry to resurrect such an old topic, but I thought the work I've recently done one the BIOS disassembly would be useful. Now, it compiles with asmsh /ol! DC.L resetPC ; Power-on reset PC DC.L $06040000 ;Power-on reset SP DC.L resetPC ; Manual reset PC DC.L $06040000 ;Manual reset SP DC.L ERR ;Gener...
by ob1
Mon Feb 15, 2021 6:39 am
Forum: Tools
Topic: 32x ASM
Replies: 3
Views: 6254

Re:

ob1 wrote:
Mon Mar 12, 2007 8:34 am
ASMSH adds a silly header and appends a byte to the binary. I've written this tool to fix it :
or you could, you know, use "/p"
by ob1
Thu Feb 11, 2021 2:54 pm
Forum: Super 32X
Topic: DMA DEI
Replies: 4
Views: 529

Re: DMA DEI

Thank you. I have retrieved the DDK. Though it seems to use all the 32X resources, the SH2 DEI seems left untouched. Indeed, I found no trace of something like "MOV.*_DMAVECTORN0", _DMAVECTORN0 being the label of DMAVCR0. Plus, the only value for DMAOR I found excluded the IE bit. So, I guess it's f...
by ob1
Mon Feb 08, 2021 2:27 pm
Forum: Super 32X
Topic: 32X Slave SH2 BIOS disassembly
Replies: 0
Views: 441

32X Slave SH2 BIOS disassembly

Yo guys. Here is a disassembly of the Slave SH2 BIOS. I went a bit further than for the master (13 years ago !!!) and I finally got the frame buffer read (it's for the Sega CD32X, stupid!). INITIAL_SP equ $0603F800 dc.l start dc.l INITIAL_SP dc.l start dc.l INITIAL_SP dc.l fail dc.l 0 dc.l fail dc.l...
by ob1
Sat Feb 06, 2021 1:19 pm
Forum: Super 32X
Topic: DMA DEI
Replies: 4
Views: 529

Re: DMA DEI

- is DEI implemented in any emulator ? Regarding Gens 2.15.4, it looks like it is not implemented. In sh2a.asm, line 5736 : ALIGN32 ; void FASTCALL SH2_DMA0_Request(SH2_CONTEXT *sh2, UINT8 state) ; ecx = context pointer ; edx = request line for external (0 = off, !0 = on) ; ; RETURN: ; nothing ... ...
by ob1
Sat Feb 06, 2021 1:16 pm
Forum: Super 32X
Topic: DMA DEI
Replies: 4
Views: 529

DMA DEI

Hello fellows. The Hitachi SH-7604 Hardware Manual defines the IE bit (bit #2) in CHCR register (§9.2.4) as : Interrupt Enable Bit (IE): Determines whether or not to request a CPU interrupt at the end of a DMA transfer. When the IE bit is set to 1, an interrupt (DEI) request is setnt to the CPU when...
by ob1
Sat Feb 06, 2021 11:00 am
Forum: Super 32X
Topic: DMA DREQ delay
Replies: 0
Views: 295

DMA DREQ delay

Once upon a time, Chilly Willy said : When doing 68K to 32X DMA via the FIFO in the 32X, it has a tendency to lose data randomly. Specifically, the DREQ fails to trigger the DMA under unknown circumstances, which means the SH2 DMA stops. If you are checking the FIFO full flags, it will "stick" at fu...
by ob1
Thu Feb 04, 2021 1:48 pm
Forum: Demos
Topic: InDev Space flies attack for Sega Genesis / MD
Replies: 5
Views: 681

Re: InDev Space flies attack for Sega Genesis / MD

I'm a simple man.
I see more than 64 colors on screen, I thumb-up.

Good luck to you ;)
by ob1
Mon Jan 25, 2021 8:00 am
Forum: SGDK
Topic: Writing multiple VSRAM values per scanline
Replies: 3
Views: 418

Re: Writing multiple VSRAM values per scanline

I'm not sure that I understood everything,
but I have played a few times with HInt, and I must say this rock stable image is great.
Bravo for this piece of work.
by ob1
Wed Jan 20, 2021 9:52 am
Forum: Megadrive/Genesis
Topic: 68K Memory access
Replies: 9
Views: 643

Re: 68K Memory access

by ob1
Wed Jan 20, 2021 9:48 am
Forum: Megadrive/Genesis
Topic: 68K Memory access
Replies: 9
Views: 643

Re: 68K Memory access

I'm not sure I correctly understood your question, but there is this block diagram that I like very much : https://gamesx.com/wiki/lib/exe/fetch.php?media=schematics:genesis_block_diagram.png (this diagram states that the address bus is 16 bits, but I'm pretty sure it is 24 bits). Here, you can see ...