Search found 433 matches

by AWJ
Fri May 25, 2018 6:43 pm
Forum: SNESdev
Topic: bsnes-mcfly: The v073 and bsnes-classic killer
Replies: 180
Views: 97952

Re: Is AWJ still in the scene? Regarding bsnes-classic

Yep, I just got his private message, too. AWJ has spoken: his project is still alive, and he wants me to rename my project. I replied to him that it would be really nice if he could either update bsnes-classic's manifest format to BML, or retire manifests and exclusively use heuristics. I'll still ...
by AWJ
Fri May 25, 2018 3:45 am
Forum: Newbie Help Center
Topic: Trying ROM Disassembly & getting lots of Invalid Opcodes
Replies: 9
Views: 4289

Re: Trying ROM Disassembly & getting lots of Invalid Opcodes

There must be some "manual" for 6502 in Japanese that shows how to do the "read data past the JSR with stack manipulations" as for some reason a lot of Japanese games I look at do it. so you get JSR somePlace .word Address, Address, Address, Address code On the 6502, this technique goes all the way...
by AWJ
Mon Oct 23, 2017 6:28 pm
Forum: SNESdev
Topic: Super Game Boy enhanced games hotpatch the SGB firmware?
Replies: 9
Views: 5021

Re: Super Game Boy enhanced games hotpatch the SGB firmware?

it's also done automatically by SGBv1/SGBv2/SGB2v1 (ie. games would need to apply the patch themselves only for SGBv0). It's actually only SGBv2 and SGB2 that contain the patch (at offset $3F400 in the ROM) SGBv1 doesn't have it. SOU_TRN Patch this patch disables H+V IRQ during SOU_TRN, unknown whe...
by AWJ
Sun Oct 22, 2017 3:36 pm
Forum: SNESdev
Topic: Super Game Boy enhanced games hotpatch the SGB firmware?
Replies: 9
Views: 5021

Super Game Boy enhanced games hotpatch the SGB firmware?

I've been looking at Game Boy stuff lately, and I noticed that most Super Game Boy-enhanced games send one or two standard sequences of DATA_SND command packets (the SGB command to transfer up to 11 bytes to an arbitrary SNES address) at startup when they detect they are running on a SGB. The payloa...
by AWJ
Thu Oct 05, 2017 6:16 am
Forum: NESdev
Topic: Drawing text in CHR-RAM
Replies: 10
Views: 3022

Re: Drawing text in CHR-RAM

Most of the time the original japanese version has fixed width character, but often a width of 8 is insufficient for kanjis and a width of 16 is too much, so they used a value in-between and pain the characters in VRAM on the fly. Also, most systems lacks enough WRAM to store all kanjis used in a g...
by AWJ
Sun Sep 03, 2017 11:40 pm
Forum: SNESdev
Topic: upd7725 overflow (attn: byuu)
Replies: 24
Views: 8049

Re: upd7725 overflow (attn: byuu)

The 7720 and 7725 appear to be pin-compatible, except that the EPROM versions of both require power on pin 1. I wonder if you could put a programmed 7720 onto a suitable SNES cartridge for software testing, rather than have to use an Arduino or something.
by AWJ
Sun Sep 03, 2017 9:42 pm
Forum: SNESdev
Topic: upd7725 overflow (attn: byuu)
Replies: 24
Views: 8049

Re: upd7725 overflow (attn: byuu)

Well, I wrote a program that should allow you to test any sequence of ALU operations you want, if someone wants to figure out how to assemble, burn and test it (don't forget the screwy bit order the '7720 needs for its program ROM) The command protocol is heavily based on the DSP-1, including the ne...
by AWJ
Sun Sep 03, 2017 7:34 pm
Forum: Newbie Help Center
Topic: Attribute / Tile
Replies: 19
Views: 5718

Re: Attribute / Tile

Yeah, I figured out a different way to calculate it, but wanted to make note of this seeming wrong, for any future readers :-) One thing to keep in mind is that unless your game uses 4x4 metatiles and only scrolls along one axis at a time Well, I am using 4x4 metatiles. But doing free all-direction...
by AWJ
Sun Sep 03, 2017 5:13 pm
Forum: Newbie Help Center
Topic: Attribute / Tile
Replies: 19
Views: 5718

Re: Attribute / Tile

One thing to keep in mind is that unless your game uses 4x4 metatiles and only scrolls along one axis at a time, you're going to have to read-modify-write attribute table bytes in order to update individual 2x2 tile cells. Since accessing PPU memory this way is extremely inefficient, you'll probably...
by AWJ
Sun Sep 03, 2017 4:16 pm
Forum: SNESdev
Topic: upd7725 overflow (attn: byuu)
Replies: 24
Views: 8049

Re: upd7725 overflow (attn: byuu)

Just noticed the question about multiply overflow in byuu's forum thread. 0x8000 * 0x8000 -> int31 is considered an "overflow" because the sign of the result is wrong. Multiplying two negative numbers should produce a positive result, but int31(0x40000000) is negative.
by AWJ
Sun Sep 03, 2017 2:36 pm
Forum: NESemdev
Topic: Advices on implementing mixed switchable and fixed PRG banks
Replies: 6
Views: 3177

Re: Advices on implementing mixed switchable and fixed PRG b

Hi, my emulator is currently only supporting mapper 0, so the PRG-ROM is just a 32 kB chunk that gets loaded at ROM load and that's it. So mappers that switch entire 32 kB PRG banks are trivial, but for mapper 2-UNROM, for example, that uses one switchable 16 kB bank and another one fixed, I've tho...
by AWJ
Sun Sep 03, 2017 2:15 pm
Forum: SNESdev
Topic: upd7725 overflow (attn: byuu)
Replies: 24
Views: 8049

Re: upd7725 overflow (attn: byuu)

PS. I think my implemention might have opposite S1 values (ie. 0=positive vs 1=positive), this works as long as SGN opcode is processing S1 accordingly. The manual is clear that the chip can distinguish between two overflows in the same direction (OV1 flag remains set) and two overflows in opposite...
by AWJ
Sat Sep 02, 2017 7:04 pm
Forum: NESemdev
Topic: VRC2/4 test program WIP
Replies: 21
Views: 25544

Re: VRC2/4 test program WIP

Attached is my modification of Nintendulator's Mapper DLL source file that passes all of AWJ's submapper identification tests. The only complaint the ROM still has is that the pseudo-scanline IRQ is "late". It looks like you were working from an outdated version of Quietust's sources. Recently (mea...
by AWJ
Sat Sep 02, 2017 8:14 am
Forum: NESemdev
Topic: VRC2/4 test program WIP
Replies: 21
Views: 25544

Re: VRC2/4 test program WIP

.byte $02, $01, Result::yes, Result::vrc4 ; mapper 23 sub 3 That should be Result::vrc2. Thanks a lot for bumping this thread; I'm embarrassed to admit I'd totally forgotten about this little project :oops: Checking my local copy of the source against the attached WIP, it seems I'd already fixed th...
by AWJ
Fri Sep 01, 2017 6:46 pm
Forum: NESdev
Topic: SimCity prototype found!
Replies: 74
Views: 28559

Re: SimCity prototype found!

The SNES has 128KB of onboard RAM, so the entire cartridge RAM can be dedicated to save data. On the NES it's most likely that one of the two cartridge RAMs is work RAM and the other is save data, just like all the Koei games. ideally yeah. but if I ever have the option to make a cart out of this, I...