MODTracker audio replay on early 68k macs

[8bitbubsy]

Yah, MOVEM would obviously give the best thruput, but I think it's hackish to put the lower byte (which can be any arbitrary value) of my 16-bit mixing buffer into the floppy drive motor speed register.

 

[8bitbubsy]

I have attached a sound recording of my software-mix PT player port playing Jester's "My Glamorous Life" on a 7.09MHz Amiga 500 in WinUAE (cycle-accurate mode). I have disabled the Amiga's 4.4kHz low-pass filter to retain that sharpness that will most likely be present on a compact Mac.

The Mac port should sound equal to this. I just hope it's going to be fast enough.

Here's the asm code for it (messy at the moment): https://www.dropbox.com/scl/fi/1ggb8tx9us8un9rdfxkjl/modplay.s?rlkey=olw8ry1b9e1x6t6fuzrc392cs&dl=1

 

[Snial]

I have attached a sound recording of my software-mix PT player port playing Jester's "My Glamorous Life" on a 7.09MHz Amiga 500 in WinUAE (cycle-accurate mode). I have disabled the Amiga's 4.4kHz low-pass filter to retain that sharpness that will most likely be present on a compact Mac.

OK, turns out I can play this in Safari ! I didn't know it had .ogg support!

The Mac port should sound equal to this. I just hope it's going to be fast enough.

It occurred to me that a standard Amiga 500 contains 100% Chip RAM, which I understand means there's contention between the video chip (Paula?/Agnes?) and the CPU. So, that 7.09MHz Amiga has a slower effective CPU speed, similar issues to a classic Mac of the era. I read in one place about half the CPU cycles were stolen. Given that the CPU frequency is already a bit slower than those Macs; I guess it means they're not too far apart, which is encouraging.

Here's the asm code for it (messy at the moment): https://www.dropbox.com/scl/fi/1ggb8tx9us8un9rdfxkjl/modplay.s?rlkey=olw8ry1b9e1x6t6fuzrc392cs&dl=1

I'll try to have a read.