Playing Atari ST Music on the Amiga with Zero CPU(arnaud-carre.github.io)
47 pointsby z3033 hours ago2 comments
  • anonzzzies2 hours ago
    I was in a Dutch demo group first for msx and then amiga, then dropped out of low level dev; the amiga coprocessors I still miss. I went to PC as everyone did and definitely at the beginning thought: what is this garbage??? We lived in the future and then it was taken from us for a while.
    • pjmlp2 hours ago
      Yeah, the closest you can get to those days is doing homebrew in something like PS3 cell units, or shader coding, which is kind of why shader competitions are so beloved in demoscene parties.
    • ndsipa_pomu2 hours ago
      I don't know if the Amiga was ahead of its time or the PC was behind its time. AmigaOS was a pre-emptive multitasking OS whilst PCs had to wait for Windows NT/95.
      • abanana2 hours ago
        The release of Windows 95 was weird. There were PC users talking about how amazing Microsoft were, to have come up with all the things their marketing people were shouting about, such as pre-emptive multitasking and plug-and-play. Then all the Amiga (and Mac) users, completely underwhelmed, pointing out "we've had all these things for years, how has it taken so long?".
        • Keyframean hour ago
          Yeah. one thing is not like the other. While AmigaOS was pre-emptive, Mac System - 6-8 weren't. It was co-op. Everyone who used 6 and 7 can remember copying file meant you couldn't do anything else, and 8 got multithreaded support in Finder finally, but it was still co-op. At the time I used various platforms daily. Namely, AmigaOS, Mac System 6-8, IRIX.. the difference was obvious. IRIX and hardware of course being from the future, but at at least 10x the price.
        • gblarggan hour ago
          Even Mac OS classic was just cooperative multitasking. Near the end it got some very limited pre-emptive capability, but most only usable to do calculations.
      • smokelan hour ago
        There were early multitasking operating systems starting with the 386, but for demos you'd typically use the entire CPU. Part of the magic was that video routines would run at an extremely constant 50 (or 60) Hz, perfectly in sync with the hardware. This, and color bleeding, resulted in a buttery smooth experience, that I still miss.

        One particular example of this experience was that you'd use "raster bars" to time the performance of your routines. If your main loop is synchronized with the vertical retrace, then switching the background color after a piece of code would show up in the margins of your screen.

        Animations were tuned to move in constant pixel offsets. All the anti-aliasing in the world cannot bring back the true demoscene spirit :)

  • bartreadan hour ago
    I never had an Atari ST so wasn't familiar with the details of how its sound chip worked. I did know it was a variant of the AY chip found in the ZX Spectrum +2A, which I did own for a brief period after several years of 48K+ ownership.

    However, it's only as a result of reading this article that I realised the chip is only capable of generating square waves and noise, whereas I'd been under the impression it had some slightly more advanced FM synthesis capabilities. That impression must have come from, decades later, listening to what people could squeeze out of the chip on various Spectrum demos on YouTube. Well, that and the fact that after the 48K beeper the 128K was never going to sound less than incredible. I might not even have had it for a year before switching to the (much less prone to go wrong) C64[0].

    Anyway, all of this to say: very interesting project, and I enjoyed the neat reversal trick with the attached voice to get the higher quality output out of Paula.

    [0] Actually the Spectrum -> C64 switch was more of a mixed bag than you might think - it wasn't, for example, like games on the C64 were all universally better. On the sound front, the C64's SID chip was a significant upgrade over the AY though, and certainly the most capable sound chip amongst 8-bit computers that I'm aware of. I really wish they'd crammed a SID chip into the Amiga alongside Paula. Or maybe even a dual SID with 6 channels for stereo output + Paula, but, alas... I'm sure it would have been cost prohibitive even if Commodore engineers had the idea at the time.

    • rbanffyan hour ago
      > I really wish they'd crammed a SID chip into the Amiga alongside Paula

      This is something the Apple IIgs had. It had an extremely capable synthesiser with good graphics and performance capped so not to compete with Macs. It was a weird machine, a sharp contrast with the minimalistic Apple IIs that preceded, over complicated and trying to be too many things at once.

      For the same reason I prefer the design of the ST over the Amiga’s. Amiga made lots of assumptions about the use that ended up tuning it well to platform games and NTSC video editing, but nothing else.