5 ms·

"metric butt-load of mask-programmable ROM" What would that be in this context? I'm guessing we're talking KB rather than TB?

jacobrobbins 7y ago
the poster mentioned it was for greeting cards, I remember their used to be a lot of greeting cards that would play a recording when you opened them. I bet they loaded low-quality samples into the ROM for that.
vardump 7y ago
I'd guess about 1 MB order of magnitude. That would be a butt-load even for samples. 1 MB would be enough for 45 seconds audio at 8 bit PCM @22 kHz. If they're half competent, they could use ADPCM or much better (and cheaper to decode too!) vector quantization. With VQ, you could go even down to ~1 bits (~6 minutes of audio per megabyte) per sample while maintaining good audio quality. Decoding is very simple, so 6502 would have plenty of oomph to do that.
- childintime 7y ago
  > [Vector quantization] Decoding is very simple. Do you have an encoder/decoder to point us to?
  - vardump 7y ago
    VQ is a very well known technique. For something quick, you might be interested to check this blog post about (unmodified) C64 playing high quality audio at 44.1/48 kHz, VQ compressed down to 96-128 kbit/s: https://brokenbytes.blogspot.com/2018/03/a-48khz-digital-music-player-for.html https://brokenbytes.blogspot.com/2018/03/a-48khz-digital-mus... There's some decoder code there as well.
  - enthdegree 7y ago
    Arithmetic coded uniform quantization works very well and is straightforward to implement!
- dTal 7y ago
  MB == Metric Buttload. Makes sense.
- Zardoz84 7y ago
  Using the trivial BTc encoding, you could archive a good compression ratio and generate audio without using a DAC . https://www.romanblack.com/picsound.htm https://www.romanblack.com/picsound.htm
a1369209993 7y ago
The 6502 can only address 64K, so I'd assume 32K of ROM at 8000-FFFF with 128 (not 100) bytes of RAM mapped at both 80-FF (zero page) and 180-1FF (for the stack) and 128 MMIO bytes at 00-7F. It depends on how much they've modified the base 6502 design, though; the above is for "not at all".
- vardump 7y ago
  In such an integrated design 6502 can address exactly as much as you want/need it to. Just implement bank switching for top 32 kB of address space. 256 banks (= one 8-bit register) * 32 kB = 8 MB. Need more? Add another bank switch register and you got up to 2 GB.
eclipxe 7y ago
For a $0.06 part? Uh, clearly not TB...

jacobrobbins 7y ago

the poster mentioned it was for greeting cards, I remember their used to be a lot of greeting cards that would play a recording when you opened them. I bet they loaded low-quality samples into the ROM for that.

vardump 7y ago

I'd guess about 1 MB order of magnitude. That would be a butt-load even for samples. 1 MB would be enough for 45 seconds audio at 8 bit PCM @22 kHz. If they're half competent, they could use ADPCM or much better (and cheaper to decode too!) vector quantization. With VQ, you could go even down to ~1 bits (~6 minutes of audio per megabyte) per sample while maintaining good audio quality. Decoding is very simple, so 6502 would have plenty of oomph to do that.

childintime 7y ago
> [Vector quantization] Decoding is very simple. Do you have an encoder/decoder to point us to?
- vardump 7y ago
  VQ is a very well known technique. For something quick, you might be interested to check this blog post about (unmodified) C64 playing high quality audio at 44.1/48 kHz, VQ compressed down to 96-128 kbit/s: https://brokenbytes.blogspot.com/2018/03/a-48khz-digital-music-player-for.html https://brokenbytes.blogspot.com/2018/03/a-48khz-digital-mus... There's some decoder code there as well.
- enthdegree 7y ago
  Arithmetic coded uniform quantization works very well and is straightforward to implement!
dTal 7y ago
MB == Metric Buttload. Makes sense.
Zardoz84 7y ago
Using the trivial BTc encoding, you could archive a good compression ratio and generate audio without using a DAC . https://www.romanblack.com/picsound.htm https://www.romanblack.com/picsound.htm

a1369209993 7y ago

The 6502 can only address 64K, so I'd assume 32K of ROM at 8000-FFFF with 128 (not 100) bytes of RAM mapped at both 80-FF (zero page) and 180-1FF (for the stack) and 128 MMIO bytes at 00-7F. It depends on how much they've modified the base 6502 design, though; the above is for "not at all".

vardump 7y ago
In such an integrated design 6502 can address exactly as much as you want/need it to. Just implement bank switching for top 32 kB of address space. 256 banks (= one 8-bit register) * 32 kB = 8 MB. Need more? Add another bank switch register and you got up to 2 GB.

eclipxe 7y ago

For a $0.06 part? Uh, clearly not TB...