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Showing content with the highest reputation on 09/29/22 in all areas

  1. Here is a very close try to what I wanted to see except one big disadvantage: you can not program in this thing. But looking from different standpoint, this is very good looking OS running on NES! Maybe more to come in this project.
    3 points
  2. Specifically, if google doesn't lie to me, Arctan{x/[sqrt(1-x^2)] = arcsin(x)
    1 point
  3. A big advantage of doing it all in a cartridge is you have the natural location for all of the I/O parts right there on the cartridge board, on the opposite edge from the cartridge port. AFAIU, on NES powerup/reset, you'd have: $0000-$07FF: NESRAM $2000-$3FFF: PPU I/O ports $4000-$5FFF: APU/Controller I/O ports $6000-$7FFF: Work RAM if installed on CART $8000-$FFF9: Cartridge ROM $FFFA-$FFFF: NMI/IRQ/RESET vectors If you have a clever enough banking scheme, you only need one RAM and one FlashROM chip. But "clever" here means setting things up so you can get from the start-up state to the normal memory map with the smallest possible boot-up code. Suppose it's 128KB each: The $8000-$FFFF decode circuitry splits between the 16KB HighRAM window in $8000-$BFFF and the 16KB ROM window in $C000-$FFFF The bottom half of RAMBank 0 appears in the WRAM space in $6000-$7FFF The banking latch has its reset pin hooked up, so on powerup/reset, the banking latch has is in its $00 state The banking latch is: bit0-bit2 = ROM A14-A16; bit3-bit5 = RAM A14-A16, bit7=RAM/ROM, bit In $00 state, ROMBank 0 is selected in $8000-$BFFF, with Bit7 of the latch selecting between ROM and RAM /OE in that space In RAMBank $00 state, RAMBank 0 is selected for $8000-$BFFF With RAM selected in $8000-$BFFF whether or not it's output is enabled, you can have the transition routine at the top of ROMBank 0 which copies itself to the top of RAMBank 0, toggles out the ROM, then calls code in the normal ROM window. Only JMP COLDSTART / ... / COLDSTART: ... / ENDROM is assembled for the ROM appearing at $8000, everything else is assembled for ROM appearing at $C000. You have eight ROM segments and eight HighRAM segments, 2KB NES RAM and 8KB "LowRAM" that also appears in $8000-$9FFF when RAMBank 0 is selected. While you can mask out RAM when setting ROM (and visa versa): "STA CALLROM : LDA BANK : AND #%1111100 : ORA CALLROM", you can also design code that allocates a ROM bank together with its own dedicated RAM bank, so, eg, "SYSCALL" executing in NESRam or WRAM is: "LDA THISBANK : PHA : LDA #SYSBANKS : STA THISBANK : STA BANK : JSR + : PLA : STA THISBANK : STA BANK : RTS : + JMP DOSYS,X".
    1 point
  4. So I have been off gallivanting around the Internet for the past year or so, looking for retro stuff, and I stumbled upon this whole group of stuff that I didn't previously know existed. You can play retro TV set, arcade, and computer games in the handheld Gameboy/PSP form factor! There are many newly made handheld game machines, with 2.8" - 6" screens, that are designed to run emulators on Linux or Android. Here's a website that catalogues them: https://www.rghandhelds.com/handheld-specs Totally insane how many there are and how many companies make them! You can buy new shells, screen upgrades, battery upgrades, and multi-game-carts, for older devices, like the super cool looking Gameboy Advance. Checkout how cool this new GBA chassis with white buttons looks. They make game controllers that mount onto smartphones. Combine an older phone with a mount-on controller and software like RetroArch and you've got a really neat retro handheld retro gaming setup. The emulators have a ton of screen filters and scaling options that make the beautiful new LCD panels look like larger, clearer CRTs or dot matrix displays, so you're not stuck with the super clean emulator look. Anyway, it's really amazing how many systems can be emulated using these handhelds. They are a lot of fun! And many of them last for 4+ hours of straight game play before needing a charge. Personally, I have two of the lesser expensive systems, the Powkiddy Q90 and the Retroid Pocket 2+. They cost me $45 and $145 CAD after shipping, respectively. The Q90 plays up to Gameboy Advance well, while the RP2+ can do SNES, N64, and some Android games, like Minecraft, Stardew Valley, and Fruit Ninja Classic. Being an Android device, the RP2+ has amazing battery life and even leaving it standby, I only charge it once or twice a week, depending on how often I use it. Truthfully, I don't play the retro games as much as I thought I would, but I really do enjoy laying in bed playing the original Gameboy version of Tetris on my RP2+, like I used on my original Gameboy back in the ancient times. I also like playing the C64 version of BurgerTime on it. Here are some helpful links: https://old.reddit.com/r/SBCGaming/ - Good starting point, with lots of links and chatter https://main.retro-handhelds.com/ - Helpful blog https://www.youtube.com/c/RetroGameCorps/videos - Video reviews of many devices and firmware https://retrogamecorps.com/ - Another helpful blog (Above Youtuber's blog) I'm not here to sell ya anything, just sharing some joy!
    1 point
  5. Hello, everyone. I have a bit of sad news to relay. https://www.mcdougalfuneralhomes.com/obituaries/scott-robison Scott Robison passed away suddenly last month, on August 16. (We just found out tonight - apparently, Scott's wife didn't have the passcode to his phone.) Scott was an invaluable contributor to the Retro community. He made some major contributions to Attack Of The PETSCII robots, was a frequent poster on the forum, and was a fun guy to talk to. We are all going to miss him.
    0 points
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