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What was Atari's reason for launching the STE?


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I am a believer that the ST initially succeeded not because it was an affordable machine, but because it was a capable machine. People just saw value on it and bought. So I agree with zzip that the moment they stopped being agresive with hardware development, they just lost it. By 1989 Apple was offering a compact model with 68030@16MHz, not to mention the Mac II, which was also 32bit and had way better video (available since 1987). With the Mac LC in 1990, apple had a 32 bit "low cost" system with the same video as the Mac II. Atari had the STE. Mac LC was also less expensive than the TT. By then Atari was behind times.

 

and you saw clock frequencies rise constantly in PC and Mac while ST and Amiga were locked at their original 1985 clock speeds forever. I know clock frequency isn't the end-all be all, but especially back then it was used as a marketing differentiator. But when the average consumer saw 25 and 33mhz PCs available, why would they even consider an 8mhz ST?

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I vaguely remember that the STFM- which had come down to £299 in late 1987- went up to £399 the following year due to increases in the cost of RAM. (Atari tried to mitigate this by bundling it with a lot of games.) This article confirms that RAM prices went up massively in 1988; ditto this contemporary report. Perhaps you're thinking of that?

 

I've no idea if you're right about the STE or not- but unless it used completely different memory chips to the STFM (and couldn't be easily redesigned to accept different ones), surely any increase in RAM prices for the STE would have affected the STFM as well? The Wikipedia article doesn't indicate a "chip famine"(!) circa 1990 or 91.

 

Also, by 1990-91, wouldn't prices have fallen enough in general so that even a (proportionately) similar increase to the 1988 one wouldn't increase the cost of 512KB by as much as it had then?

 

You may well be right, but I do defintely remember STe's going up in price by a chunk, memory did fluctuate quite wildly during that period. I will have to read through some old ST Formats, as I suspect the article is in there. It doesn't take much for memory prices to sky rocket, just look at the price of ram today compared to a year ago, it's gone from £50 to around a £100 for c. 16gb :)

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And we aren't even talking about the OS. By late 1987 the Mac was already capable of cooperative multitasking. By the time we got TOS 1.4, Mac users were already enjoying System 6.

 

Ai but then Atari (and Amiga which had it from the start) had proper preemptive multitasking well before the Mac did, and cooperative multitasking on the Mac from that period has some serious problems (i.e. the machine virtually locks up anyway if something hogs the CPU). We should also not forget that Apple were almost of the verge of following Atari and Commodore into technology oblivion in the mid-nineties before Steve Jobs realised that if you stuck the same machine in a trendy case you could sell computers by the bucket load ;) Those LCs suffered from the same faults the Falcon had, that 32bit chip with a 16bit bus to cut costs, but really the TT is reasonably comparable to the Mac II (albeit too late), and the Falcon has virtually identical specs to the LC machines from the same time frame (bar the DSP). But I agree, that successor machine to the ST really did need to come out with at least a double clock speed and beefed up graphics/ sound in 1988/ 1989, and the price advantage had gone shortly after that point with Apple scraping the low end. Atari also distracted themselves with PC hardware and transputers (which I think they thought were the future) in the late eighties, which didn't help.

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And yet the only thing left is for us to keep enjoying our Ataris and if possible make contributions in terms of hardware and software.

As much as we love to blame the Tramiels, I don't think Atari Warner was doing any better. They had Alan Kay working for them for a couple of years and they couldn't even produce a truly updated version of the 8 bits. Now that is mismanagement.

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As for the ST running AmigaDOS/Workbench, it should be noted that the Blitter is implemented in running the desktop environment.

 

I'd assume it would use the blitter- or any other hardware support- if it's available. (IIRC, didn't TOS on the ST also automatically use the blitter when executing standard OS calls to the graphical subsystem if installed?)

 

My point was that the OS didn't seem to be *reliant* upon these advantages; i.e. while graphical updates might run a little slower without the blitter, I'd still expect the OS as a whole to be workable. Indeed, I might be wrong, but I'd assume that it should be able to be ported to the ST hardware without any fundamental changes to its design.

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In the UK there were P.R statements from Atari saying they needed to introduce new hardware revisions if the ST range to prevent the market from going stale..so the annoucement of the Super ST as press labelled it wasn't a surprise, sadly it wasn't the Amiga Killer CTW had promised though.

 

Having chatted to a good few UK coders over time, I know whilst many appreciated how easy the ST was to code for, many found the lack of hardware scrolling and limited, in comparison to the Amiga, colour palate and very limited sound chip, limited what could be done.

 

So, we're keen to embrace the superior hardware the Amiga offered.

 

I've always seen the STE as Atari trying to stem the flow as it were of coders,artists etc leaving the ST in favour of the Amiga.

 

Sam Tramiel described them as slitting their own throats, saying how easy it was to port games from Amiga to the ST, but clearly many didn't want to compromise on audio,visual features the Amiga offered as standard.

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It did, supply for ST's here in the US was nearly non existent, just in time for a500 which we could get in good supply.

 

I don't recall reports of a shortage in the UK, only of the price going up. According to this post, Tramiel gave preference to European markets because they were more profitable:-

 

Atari wouldn't send small dealers any stock. Everything went to (1) Europe (more profitable) and (2) LARGE dealers (big profitable deals).

 

So I'm guessing that if he was having trouble sourcing affordable RAM, the machines he could produce were more likely to end up here.

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I don't recall reports of a shortage in the UK, only of the price going up. According to this post, Tramiel gave preference to European markets because they were more profitable:-

 

 

So I'm guessing that if he was having trouble sourcing affordable RAM, the machines he could produce were more likely to end up here.

yes shortage was in the US.(where I am), US supply was switched to UK. Atari was focusing on europe when this happened. Really hurt US ST sales, could not have been at a worse time.

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And yet the only thing left is for us to keep enjoying our Ataris and if possible make contributions in terms of hardware and software.

As much as we love to blame the Tramiels, I don't think Atari Warner was doing any better. They had Alan Kay working for them for a couple of years and they couldn't even produce a truly updated version of the 8 bits. Now that is mismanagement.

 

That next-gen effort happened in 83-84 and was killed by Jack when he bought the company. He came to Atari with the ST design, he didn't need the ones they were working on. Who knows what would have happened otherwise? Atari was on track to receive the Amiga chips. In an alternate timeline, who knows? Maybe they would get them.

 

Yes there was mismanagement at the Warner Atari. But on the other hand, Warner Atari had much better marketing and distribution resources than Tramiel's Atari ever did.

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It's true that the STE only has 4 playback rates (unlike the Amiga that has variable playback rates) but that doesn't mean you need multiple samples to play other notes.

 

I assume you mean rendering sample fragments in real time? I'd argue that's still "multiple samples"- it's just that you're creating them "on the fly" rather than holding them in memory.

 

That said, I'm nitpicking semantics ;-) , so let's skip that and get onto the real issue...

 

 

For Amiga like tracker music you need to mix the 4 channels and adjust the sample frequency in software. So it indeed costs more CPU time [..] But this makes it also more flexible because the software mixing makes for example stereo panning and more than 4 channels possible.

 

I'm sorry, but this is trying to make a virtue out a limitation.

 

If it had been so great, there was nothing stopping you from doing the same (very CPU-intensive) software mixing on the Amiga. Indeed, I was actually going to use OctaMED as a counter-example until I saw you'd already mentioned it! It was clever, but I remember it slowed down the computer quite significantly in 8 channel mode.

 

In theory, even the regular STFM could play back sampled sound to not-too-far-off-the-Amiga quality by crude "bit bashing" of the 8-bit era soundchip with PCM values. (#) But you didn't see that often in games, presumably because the CPU load- and strict timing required- make it impractical. And the "real time re-sampling" solution to the STE's limitations has the same problem.

 

The need- as opposed to the choice- of carrying out CPU-intensive software-based mixing to get around the limitations of the hardware in the STE doesn't indicate an advantage. Quite the opposite- it's a serious limitation, pure and simple.

 

(#) Technically, most of the "square wave" 8-bits could manage sample playback in a similar manner; I wrote a routine to do it on my Atari 800XL, and I was never an expert programmer.

 

 

The Atari Falcon added a DSP processor were the software mixing of samples could be done in the DSP thus offloading the main 680x0 processor.

 

If a machine is using a DSP like the Falcon did, I wouldn't consider that "software mixing"- it's dedicated hardware designed to take the load off the CPU.

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In theory, even the regular STFM could play back sampled sound to not-too-far-off-the-Amiga quality by crude "bit bashing" of the 8-bit era soundchip with PCM values. (#) But you didn't see that often in games, presumably because the CPU load- and strict timing required- make it impractical. And the "real time re-sampling" solution to the STE's limitations has the same problem..

 

In theory? It was actually fairly common to find vanilla ST games using sampled sound in this manner. There were even .MOD players that ran on vanilla STs. There was always a slight hiss and tinniness to these samples when compared to STe's DMA sound though, but it was better than nothing.

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That next-gen effort happened in 83-84 and was killed by Jack when he bought the company. He came to Atari with the ST design, he didn't need the ones they were working on. Who knows what would have happened otherwise? Atari was on track to receive the Amiga chips. In an alternate timeline, who knows? Maybe they would get them.

 

Yes there was mismanagement at the Warner Atari. But on the other hand, Warner Atari had much better marketing and distribution resources than Tramiel's Atari ever did.

 

Wasn't the Advanced Research team already gone by the time the Tramiels took over? I thought James Morgan was the one who actually let them go...

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In theory? It was actually fairly common [..] There were even .MOD players that ran on vanilla STs.

 

Badly phrased in hindsight, as that's not what I meant to imply... particularly as I had- and remember- one of those MOD trackers myself when I owned a 520STFM in the early 90s!

 

(I think I was trying to say that it *was* technically possible- but not by design and with limitations.)

 

I don't recall hearing that much use of samples during actual in-game play, though. I'll admit that I only had my ST for a year or so (and not that many games). However, from what I've seen on YouTube, most of them still went with the horribly dated square wave sounds the chip was designed around.

 

There was always a slight hiss and tinniness to these samples when compared to STe's DMA sound though, but it was better than nothing.

 

I don't remember it that clearly, but I'm guessing this may have been because- since the STFM's bit-bashed samples wouldn't have had the advantage of a hardware cutoff filter for high frequencies- the jagged edges of the unsmoothed PCM would have resulted in aliasing and noise.

Edited by Mostro
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I'm sorry, but this is trying to make a virtue out a limitation.

The need- as opposed to the choice- of carrying out CPU-intensive software-based mixing to get around the limitations of the hardware in the STE doesn't indicate an advantage. Quite the opposite- it's a serious limitation, pure and simple.

 

Sorry, it was not my intention to make it look like if software mixing is much better than than hardware.

The Amiga sound hardware has of course as great advantage that it takes little CPU time to play multiple samples compared to the STE's software mixing.

I was merely saying that software mixing has its advantages (flexibility) at the cost of CPU time. It is just a trade off between CPU and flexibility. It is funny that Amiga programmers used Atari ST techniques (started by Atari ST musician Jochen Hippel with 7-track TFMX player used in for example Turrican and Lethal Xcess) to overcome the limitations of the Amiga sound hardware like more than 4 tracks and stereo panning in OctaMED where the hardware has strict left/right separation.

 

Similarly Amiga programmers used the more time consuming blitter objects (Blobs) to overcome the limitations of the build-in hardware sprites.

 

 

If a machine is using a DSP like the Falcon did, I wouldn't consider that "software mixing"- it's dedicated hardware designed to take the load off the CPU.

 

The DSP is still running a software program that is doing the mixing, it is not "hardwired" in hardware :P Similar the NeoGeo and MegaDrive used a secondary CPU (Z80) processor for sound processing. Would you consider the Z80 sound code on those machines also *not* software? In my view it doesn't matter if the software is running on a secondary CPU to consider it "software mixing" as long as the "algorithms" are not fixed in hardware.

 

Also the DSP is *not* dedicated to sound processing but is great at doing it. The DSP could be (and has been) used for lots of other things like Fractal calculation, image processing, compression, etc.

 

 

I don't recall hearing that much use of samples during actual in-game play, though. I'll admit that I only had my ST for a year or so (and not that many games). However, from what I've seen on YouTube, most of them still went with the horribly dated square wave sounds the chip was designed around.

Actually there are numerous games that used samples for sound effect on a original ST during game play, even while playing an YM tune at the same time. Examples are GoldRunner and IK+. Samples were also used in YM music (known as digidrum) in for example Wings of Death and Lethal Xcess. But indeed full Amiga like tracker music was usually only used in title screens because it takes lots of CPU time but the STE games Star Dust and Pinball Obsession used tracker music during the game.

 

Robert

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I don't remember it that clearly, but I'm guessing this may have been because- since the STFM's bit-bashed samples wouldn't have had the advantage of a hardware cutoff filter for high frequencies- the jagged edges of the unsmoothed PCM would have resulted in aliasing and noise.

 

Could be. I always assumed it was just from low sample rates

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It is funny that Amiga programmers used Atari ST techniques (started by Atari ST musician Jochen Hippel with 7-track TFMX player used in for example Turrican and Lethal Xcess) to overcome the limitations of the Amiga sound hardware like more than 4 tracks and stereo panning in OctaMED where the hardware has strict left/right separation.

 

It's not really "funny", it's quite sensible to borrow good techniques, and not surprising that they might have originated on the ST. The limitations of its inbuilt sound hardware would- I assume- have provided a greater impetus to overcome them, whereas the Amiga's audio limits (which undeniably existed) weren't that much of an issue until later on, because the early software didn't really fulfil its potential.

 

(Now that you mention it, it would have been nice if latterly they'd upgraded the soundchip to support hardware-based panning, since I assume that wouldn't have required a major redesign.)

 

 

The DSP is still running a software program that is doing the mixing, it is not "hardwired" in hardware :P Similar the NeoGeo and MegaDrive used a secondary CPU (Z80) processor for sound processing. Would you consider the Z80 sound code on those machines also *not* software? In my view it doesn't matter if the software is running on a secondary CPU to consider it "software mixing" as long as the "algorithms" are not fixed in hardware.

 

Also the DSP is *not* dedicated to sound processing but is great at doing it. The DSP could be (and has been) used for lots of other things like Fractal calculation, image processing, compression, etc.

 

Ah, now you are arguing semantics. :)

 

Technically, that's correct. However, when I talked about doing something "in software", I meant purely using the machine's existing processing functionality to accomplish a task- rather than relying upon additional *hardware* intended to aid it in that purpose.

 

The DSP is a piece of additional *hardware*, and while it might- in theory- be turned to other, more general uses, it's quite clearly designed with digital signal processing in mind. (The clue's in the name ;-) ).

 

My point was that the Falcon is somewhat different to the STE, because it has additional hardware for that sort of processing. (But not forgetting that the STE *does* have hardware-based sample playback- it's just that we're discussing doing things "in software" because of the playback rate limitations).

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Could be. I always assumed it was just from low sample rates

 

If the analogue source contains any frequencies too high for the (low) sampling rate, that would cause artifacts, but that'd be an issue for the sampling hardware- which might well not be an ST anyway- and the sample itself.

 

Then again, such sampling would probably be done with playback limitations in mind. And I'm guessing that moderate artifacts introduced in this manner were probably tolerated in preference to the muffling that'd be caused by completely low-pass filtering the source(?)

 

I'm still pretty sure that the "jaggies" caused by unsmoothed bit-bashing would cause some unpleasant high-end harshness, though I'm not sure whether it would translate into hiss?

 

I could waffle further on this, but I don't intend boring everyone with (potentially misinformed) guesswork based on my half-baked- well, quarter-baked!- understanding of sampling theory. :_(

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Ah, now you are arguing semantics. :)

 

True :), I understand your reasoning. You could indeed consider extra hardware that is meant to offload the main CPU a hardware solution even when it runs software.

 

 

 

The DSP is a piece of additional *hardware*, and while it might- in theory- be turned to other, more general uses, it's quite clearly designed with digital signal processing in mind. (The clue's in the name ;-) ).

 

True, the clue is indeed in the name :P, digital signals are not only audio signals but could be any signal. The Fourier Transformations the DSP is very good at can be used for non audio signal (JPEG, earthquake vibration analysis, magnetic resonance imaging (MRI) signal processing, infrared spectroscopy, modulation for DSL modems (actually anything that is a wave)).

The Motorola documents do not advertise the DSP as a audio processor but spend about two pages about possible applications of which only 6 bullets are about audio processing. But you are right that the DSP in the Falcon was mainly intended for audio processing.

 

Robert

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If the analogue source contains any frequencies too high for the (low) sampling rate, that would cause artifacts, but that'd be an issue for the sampling hardware- which might well not be an ST anyway- and the sample itself.

 

Then again, such sampling would probably be done with playback limitations in mind. And I'm guessing that moderate artifacts introduced in this manner were probably tolerated in preference to the muffling that'd be caused by completely low-pass filtering the source(?)

 

I'm still pretty sure that the "jaggies" caused by unsmoothed bit-bashing would cause some unpleasant high-end harshness, though I'm not sure whether it would translate into hiss?

 

I could waffle further on this, but I don't intend boring everyone with (potentially misinformed) guesswork based on my half-baked- well, quarter-baked!- understanding of sampling theory. :_(

 

I wouldn't say it was a hiss so much as having a tinny-sounding quality to it. I'm no expert in digital audio either. I mean, ST games having all these samples in them certainly had a wow factor at the time, enough that I didn't notice how poor the quality was-- until I got an STe and realized how much clearer it sampled sound was on it.

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I wouldn't say it was a hiss so much as having a tinny-sounding quality to it.

 

I might have been thinking along the right lines then- that "tinniness" could well be the square-wave flavoured "harshness" I had in mind.

 

Almost forgot one thing I'd read which is going to make this problem much worse (along with explaining why sample playback on the vanilla ST is mediocre). From what I've read, the basic bit-bashing technique on the original ST only supports 4-bit (i.e. 2^4 = 16 level) audio resolution (#) rather than the 8-bit (256 level) audio of the Amiga and STE(?) or Compact Disc's 16-bit (65,536 level).

 

This image shows just how horribly coarse 4-bit is. It means that beyond a certain point, high sample rates (i.e. the "horizontal" resolution) aren't going to buy you higher quality if you still only have sixteen output levels (i.e. the "vertical" resolution) to jump between. (##)

 

So, in addition to the poxy resolution, there are going to be major, unsmoothed jagged edges (###) with sample playback on a regular ST, and that's going to have a major negative effect on the quality.

 

I've heard of people combining the output level of multiple channels (and other aspects of the chip) to go above 4-bit quality, but I'm pretty sure it's never going to match 8-bit, hardware-based sample playback. (Besides which, wouldn't it effectively reduce you to one audio channel?)

 

(BTW, if anything I've said here is incorrect or misleading, feel free to point that out).

 

---

 

(#) Assuming the process is similar to sample playback on my 800XL's (also square-wave based) POKEY soundchip, this'll be because the output level per channel can only be set to one of sixteen positions. AFAICT these corresponded to the 16 volumes of square wave it could generate in normal usage (presumably by toggling abruptly between zero and the desired position at the correct frequency).

 

(##) This assumes that oversampling isn't possible. (From my limited understanding of the subject, this wouldn't be possible on the ST since it would require hardware-based filtering of the output on top of much higher sample rates.)

 

(###) Smoothing them off effectively being what a low-pass filter would do here- something which the standard ST soundchip doesn't have, since it was never designed for sample playback.

Edited by Mostro
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(BTW, if anything I've said here is incorrect or misleading, feel free to point that out).

 

OK, I'll bite ;)

 

You really are conflating a bunch of different things and painting a worse picture than reality (not that the vanilla ST sample playback is stellar....)

 

4 bits of amplitude is certainly more coarse than 8 bits, but, given good samples and a decent sample rate, it could still sound fairly good. For instance, although CD's are indeed composed of 16 bit samples (well almost always, but that's another day), those samples are often played through a 1 bit DAC. Yes, much higher sample rate than our lowly ST sound chip, but by the same argument you present, 4 bits is WAY more than 1, so the ST is obviously better than CD quality? :-o

 

That said, the ST isn't massively oversampling on playback, so the limited quantization levels certainly can come into play, again depending on the original samples. Much like mixing colors or multiplexing sprites, toggling amplitude in the samples 'fast enough' can create the illusion of additional quantization levels. Also, keep in mind that we really discern amplitude as power, so there's a time factor involved as well.

 

Regarding filtering, that's really going to come down to how the original samples were crafted and what rate they are played back. So long as our original samples don't have any frequency content greater than 1/2 our playback rate, you won't have any aliasing, and you won't have to rely on filters to address it.

 

None of that is to say that vanilla ST is some kind of sample driven powerhouse, it certainly is not, but given the hardware limitations, the end result depends greatly on the source material and techniques, and only somewhat on the actual sound chip (and in truth, this is because of the limitations of the sound chip)

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But you are right that the DSP in the Falcon was mainly intended for audio processing.

 

If I remember correctly, the Falcon was mentioned in one of the Amiga magazines the same month they announced the A4000 (i.e. the first AGA Amiga).

 

I'll admit that I do remember thinking some of the specifications looked pretty nice. (Bear in mind that- IIRC- the affordably-priced A1200 hadn't been announced yet). Unfortunately, I also remember knowing- even at the time, and without the benefit of hindsight- that it didn't stand a cat's chance in hell.

 

Firstly, it was clear that Atari couldn't market their way out of a paper bag.

 

Secondly, the ST line- of which the Falcon was still effectively a descendant- had been in decline in the face of the Amiga since the end of the 1980s, even on the UK market. By this point was practically yesterday's news. At a time when it was starting to become clear that the tide was turning against even the Amiga and in favour of the PC.... Well, if there was any company that could achieve the miracle of persuading the mass market to move back to the ST, it sure as heck wasn't going to be Atari.

 

So, interesting looking machine. Not remotely surprised that it didn't go anywhere, or that they (apparently) ditched it a year later.

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You really are conflating a bunch of different things

 

 

With respect, I'm not convinced that I am- at least, not in the specific aspects you raise. I think you're either miscontruing what I said... or I explained myself badly, which is just as likely(!)

 

 

4 bits of amplitude is certainly more coarse than 8 bits, but, given good samples and a decent sample rate, it could still sound fairly good.

 

I'll admit that from what I- vaguely- remember, and have seen on YouTube (assuming the playback is via a standard ST), the sound quality is still better than the harsh impression I gave above. It was just an attempt to explain where the "tinniness" might come from, which I assume is related to the sharp corners, and the spurious high frequency artifacts one would expect to be associated with such distortion of the original waveform.

 

 

Although CD's are indeed composed of 16 bit samples (well almost always, but that's another day), those samples are often played through a 1 bit DAC. Yes, much higher sample rate than our lowly ST sound chip, but by the same argument you present, 4 bits is WAY more than 1, so the ST is obviously better than CD quality? :-o

 

You've got that the wrong way round- I specifically mentioned oversampling in the footnote because I wanted to qualify that what I'd said didn't extend to general theoretical principle. (And yes, it was the 1-bit DACs in CD players I had in mind). At the same time, it was relegated to a footnote because I didn't believe it could be usefully applied to the situation under discussion (i.e. bit-bashed sample playback on a standard ST).

 

I don't feel the analogy comparing 1-bit DACs with the ST's 4-bit audio is legitimate.

 

As far as I'm aware, 1-bit DACs rely upon- as a fundamental and integral aspect of their design- post-processing and/or low-pass filters to accurately reconstruct the intended signal. The ST soundchip- of course- has nothing like this, because it was never designed with sample playback in mind, let alone oversampling!

 

And I don't know exactly what the audio output of a 1-bit DAC (which I assume would effectively be a pulse width modulated signal?) would sound like if it was fed directly to an amplifier without these steps. I assume that much of the distortion would be way, way above the range of human hearing, and that the amplifier itself would effectively filter out frequencies much higher than it was designed for.

 

Yet, while I'll guess that the signal unintentionally filtered in this way might more closely resemble the intended waveform than the purely rectangular stream of output from a 1-bit DAC, it would still have enough audible distortion to make it less then pleasant to listen to.

 

 

 

Regarding filtering, that's really going to come down to how the original samples were crafted and what rate they are played back. So long as our original samples don't have any frequency content greater than 1/2 our playback rate, you won't have any aliasing, and you won't have to rely on filters to address it.

 

 

Yes, I'm aware of the Nyquist-Shannon theorem; or at least its basic principle.

 

FWIW, I had that it in mind when I said that "I'm guessing that moderate artifacts introduced in this manner were probably tolerated in preference to the muffling that'd be caused by completely low-pass filtering the source(?)".

 

In other words, I knew that one could (theoretically) avoid artifacts by filtering out everything above half the sampling rate, but I suspected that in practice, that might have been intentionally ignored- assuming the people in question understood Nyquist!- if any moderate artifacts introduced were preferable to the loss of top end on the sample.

 

Also, bear in mind that Nyquist only states what's theoretically (and mathematically) possible. In practice, it's not always easy- or even practical- to do things that perfectly. For example, it's very difficult- particularly with analogue filters- to perfectly remove all frequencies above a certain point while leaving those below untouched. The cutoff is generally more like a curve/slope than brick wall, so you have to either filter well below the desired frequency to avoid some higher ones getting through, or tolerate some above the limit- and the risk of artifacts- anyway.

 

In addition, I've no idea what- if anything- the Nyquist-Shannon theorem says about the effect of quantisation on the individual point samples (i.e. the digitisation of the original theoretically "infinite" analogue value to quantised 4, 8 or 16-bit values). I'm guessing it says nothing at all- because that's not what it's supposed to be about!- but nonetheless, there must be some effect on the result if the resolution is low enough.

Edited by Mostro
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I guess what I was driving at, is that there are a lot of potential noise sources for the vanilla ST sampled output, and you sort of nibbled around the edges, but there's really a lot more to it than what you've researched. The distortions you have identified are definitely there, but not for the reasons you might think. You can generate reasonably good output with the vanilla ST hardware (or worse). Certainly, the limitations you correctly identify don't make it easy, but it really is more about the source material and how it is manipulated than the exact specs of the hardware. Would better sound hardware been a good move on Atari's part? Absolutely (hence the STe DMA sound).

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