Search found 21692 matches

by tepples
Thu Feb 20, 2020 10:15 am
Forum: SNESdev
Topic: 4-bit graphics corpus for compression research
Replies: 0
Views: 104

4-bit graphics corpus for compression research

Say I want to test theories about graphics compression, such as adapting UFTC/XFTC or some sort of RLE or XOR Huffman to TG16, SMS, Genesis, Super NES, or GBA. I'd like to run multiple codecs on a corpus, compare their rate and decoding time, and post the corpus, codecs, and results on GitHub so tha...
by tepples
Wed Feb 19, 2020 1:37 pm
Forum: NESdev
Topic: divide by 10
Replies: 4
Views: 255

Re: divide by 10

If the divisor is fixed at 10, "the usual division routine" unrolls to this 55- to 59-cycle fragment: ldx #0 stx quotient cmp #160 bcc @L1 sbc #160 @L1: rol quotient cmp #80 bcc @L2 sbc #80 @L2: rol quotient cmp #40 bcc @L3 sbc #40 @L3: rol quotient cmp #20 bcc @L4 sbc #20 @L4: rol quotient cmp #10 ...
by tepples
Mon Feb 17, 2020 10:09 am
Forum: SNESdev
Topic: Hardware-implementable emulator inaccuracies
Replies: 3
Views: 224

Hardware-implementable emulator inaccuracies

If [games made for ZSNES] don't work on real hardware they certainly shouldn't be allowed to work on an emulator either. Then the obvious solution is to build real hardware that runs them :twisted: Expand ARAM to 128K Option to put echo buffer in top half ($10000-$1FFFF). No incomplete results for ...
by tepples
Mon Feb 17, 2020 9:43 am
Forum: SNESdev
Topic: Mesen-S - SNES Emulator
Replies: 288
Views: 113807

Re: Mesen-S - SNES Emulator

In before someone builds hardware that modifies the platform to use 128K ARAM, with the echo buffer in the top half.

Split to Hardware-implementable emulator inaccuracies.
by tepples
Fri Feb 14, 2020 1:24 pm
Forum: NESemdev
Topic: using nes test ROM to test 6502 CPU
Replies: 1
Views: 147

Re: using nes test ROM to test 6502 CPU

Starting at $C6BD, nestest.nes indeed tests the behavior of those unofficial 6502 instructions that are stable. However, only about a dozen pre-1997 licensed and unlicensed games rely on them. If you're that far, you can stop and begin the PPU if you wish. Further reading: CPU unofficial opcodes ; P...
by tepples
Fri Feb 14, 2020 1:23 pm
Forum: SNESdev
Topic: I wrote up a "brief" explainer on SNES cartridges
Replies: 19
Views: 2426

Re: I wrote up a "brief" explainer on SNES cartridges

nocash wrote:
Fri Feb 14, 2020 10:07 am
No, that's nonsense the SNES does draw (consume) power, it does not supply (generate) power.
Both. It draws power through a 7805 regulator, and it uses some of that power to supply power to the Game Pak and controllers connected to it. ("Supply" doesn't necessarily mean "generate".)
by tepples
Thu Feb 13, 2020 7:07 pm
Forum: Other Retro Dev
Topic: Sega Genesis rom/sram address mapping
Replies: 29
Views: 26267

Re: Sega Genesis rom/sram address mapping

Write one value to $A130F1, and $000000-$3FFFFF is ROM. Write another value, and $000000-$1FFFFF is ROM and $200000-$3FFFFF is RAM.

Further reading: "Saving progress with SRAM: Games larger than 2MB" and "MOVEP instruction: Using movep to read/write SRAM" on Plutiedev
by tepples
Thu Feb 13, 2020 6:00 pm
Forum: GBDev
Topic: Specifying the .sym format
Replies: 0
Views: 155

Specifying the .sym format

The .sym file format is used by the debugging features of NO$GMB and bgb emulators. WLALINK and RGBLINK generate this format, and the mgbdis disassembler accepts it as input. Each nonblank line contains either a semicolon and comment or a bank (1-3 hex digits), colon, address (4 hex digits), whitesp...
by tepples
Thu Feb 13, 2020 10:10 am
Forum: Other Retro Dev
Topic: Sega Genesis rom/sram address mapping
Replies: 29
Views: 26267

Re: Sega Genesis rom/sram address mapping

Games larger than 2 MiB that have battery-backed SRAM have a mapper to switch $200000-$3FFFFF between the upper 1 or 2 MiB of ROM and the SRAM.

The 68K architecture is big-endian: $1234 is stored as 12 34. This means $200000 is high and $200001 is low.
by tepples
Wed Feb 12, 2020 6:46 pm
Forum: SNESdev
Topic: Jump exection code to RAM
Replies: 6
Views: 569

Re: Jump exection code to RAM

Or when making a Super Game Boy native mode game (like Space Invaders). Or when making a multicart menu (similar to removing the cartridge).

Something I plan to do this year, and something I've done.
by tepples
Wed Feb 12, 2020 12:22 pm
Forum: General Stuff
Topic: Word of notice: Byuu is changing usernames
Replies: 10
Views: 1107

Re: Word of notice: Byuu is changing usernames

byuu wrote:
Wed Feb 12, 2020 12:19 pm
I'm updating the name in places that allow me to. phpBB3 isn't one of them.
If you do want a username change, feel free to request one.
by tepples
Thu Feb 06, 2020 8:44 am
Forum: General Stuff
Topic: Word of notice: Byuu is changing usernames
Replies: 10
Views: 1107

Re: Word of notice: Byuu is changing usernames

In before the obligatory Far Automata jokes...
by tepples
Wed Feb 05, 2020 7:43 pm
Forum: NES Hardware and Flash Equipment
Topic: Broken PPUs/CPUs from China
Replies: 9
Views: 612

Re: Broken PPUs/CPUs from China

Check your soldering on the pin that carries VRAM A2/D2 and PPU-to-CPU D2. (On a PPU with the same pinout as the NES PPU, these are pins 36 and 4 respectively.)
by tepples
Wed Feb 05, 2020 8:19 am
Forum: Web Issues
Topic: Are the account activation emails working?
Replies: 4
Views: 440

Re: Are the account activation emails working?

User dinkc64 is now dink
by tepples
Tue Feb 04, 2020 4:47 pm
Forum: Newbie Help Center
Topic: 8x16 and whatever else unreg wants to know
Replies: 1554
Views: 387358

Re: 8x16 and whatever else unreg wants to know

tokumaru wrote:
Tue Feb 04, 2020 3:41 pm
Well, external hardware simply can't change a flag inside the CPU.
For the sake of completeness, there is one exception that applies to some other applications of the 6502, but not the NES. Thus I won't go into detail about it.