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StinkerB06

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  1. You don't necessarily have to store all of your sprites in VRAM at once. If you only have one sprite on-screen that uses those 17 frames of animation in the screenshot you posted, just keep one of those animation frames in VRAM at a time and copy the next one from RAM to VRAM when needed. However, this will impact performance.
  2. I thought the YM3012 was just used to convert the digital audio bitstreams from the YM2151 into analog audio outputs. Like, the CPU wouldn't be able to address it.
  3. The YM2151 has more channels (8 versus 6). The YM2612 has only 6 channels and not 7, as the DAC shuts off the 6th FM channel. Both of these have 4 sine-wave operators per channel, and include 8 different ways of combining these operators together. The YM3812 is a 2-operator chip that supports 3 more waveforms, and 9 channels. The chip could be switched into a mode which replaces the last 3 FM channels with 5 channels of unique percussion sounds controlled with the FM channels' patch registers. This means the chip can produce up to 11 channels of sound at once.
  4. But @Frank van den Hoef did confirm in another thread here that an LFSR is used in the hardware HDL. He didn't give any specifics though, like the LFSR's width and what taps it uses, or if it's shared or per-channel.
  5. Has the VERA PSG's noise LFSR algorithm been revealed yet? It's not implemented in the emulator's PSG code as far as I'm aware.
  6. How is this a coincidence? What am I missing?
  7. I guess because it has 16 PSG channels?
  8. Using BNE instead of BRA or JMP is a way to automatically terminate printing if the string ever goes above 256 characters. Once X contains $FF (index of the 256th character), and the INX is executed, the value in the register will wrap back to $00. The Z flag in the processor status register is set to indicate a result of zero. Since BNE branches only if Z is cleared, the branch never sends the program back to "Loop" to repeat for any more characters, and falls down to the RTS. If you didn't use BNE, then printing a string that's 256 or more characters long will cause the loop to never end, repeatedly outputting the first 256 characters over and over. Unless the interrupt handler somehow modifies the string so that a terminator ($00) is present, you have to reset the machine.
  9. I thought I heard the X16 command prompt uses layer 1 and not 0?
  10. The VERA has PSG registers located from $1F9C0 to $1F9FF. I think the best solution is to have the PETSCII character set moved to $1F000, so that bank 0 now holds enough capacity for 64 KB worth of tiles. $1F9C0 onwards has no longer been general-purpose video memory ever since the VERA 0.9 changes got put in place. Palette and sprite registers used to be in separate bins, but now they hog the very end of VRAM.
  11. 2 out of 256 bytes? Doesn't sound like very much to me! Those are the same addresses as the 6510's I/O direction and data registers, itself is used in the C64. Oh, if I remember, ZP locations $02 to $7F are allowed to be used by the user, locations $80 to $FF are used by the kernel. $02 to $21 supposedly are designed to be sixteen virtual 16-bit registers (or 32 8-bit registers, since changing values in memory must be done on a byte-by-byte basis). You can see these defined within @SlithyMatt's assembly code.
  12. Also, I see you use a BRA instruction in your code, which is on the 65C02 but not the original.
  13. I mean, some assemblers use/support INA and DEA for consistency with the X and Y equivalents, but those aren't official.
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