Why did the Atari ST designers use such a CRAPPY sound chip?

[Bruce Abbott]

Originally Posted by ImmortalA1000

Bob wanted to do much more and also improve the quality of what was there but Commodore weren't interested so he left as I understand it. Can you imagine, guy designs one of the best sound chips of all time and still wants to improve it. Of course Commodore ruined the cool bugs with the 'fixed' 8580 so now many many games are just annoying on a 64C which is crazy when you think that's all you could buy for half the model's product life cycle.

Let's see if I've got this right. Commodore isn't interested in improving the SID chip - bad Commodore! Commodore improves the SID chip - bad Commodore!

What's crazy is Commodore being blamed for fixing bugs that naughty programmers were taking advantage of.

I know what Atari was thinking, you get the YM chip to make some noise, you want better you get MIDI gear. Trouble is YM is bottom of the barrel 'freebie' in the case and because MIDI is for professionals you are talking much more than the cost of a 520STFM for a decent MIDI sound module so you are kind of stuck.

But YM wasn't 'bottom of the barrel', it was Yamaha's enhancement of the popular AY-3-891x sound chip used in many arcade machines and home computers, including the contemporary Amstrad CPC and ZX Spectrum+2 and +3, and the Mockingboard sound card for the Apple II.

Worse sound chips were used in many other machines. The BBC micro, Sega SC3000, Sord M5, IBM PC Jr, Tandy 1000 and others used the less capable SN76489. Tandy color computers had a 6 bit DAC that needed 100% CPU time to make music. The ZX Spectrum, Apple-II and several others were bit-banged, and the IBM PC and Sinclair QL had a single square wave tone generator.

PC owners spending $1000s on an EGA turd for 'home use' may have the funds to buy $500 MIDI module/cards etc but this doesn't work for the rest of the world where you are looking to spend under £500 for a home computer for family use.

Yep, which is why the Atari ST got a YM2149.

If we ignore the C64 and Amiga, what was the first home computer of note to have a better sound chip? The first PC card with FM synthesis was the Adlib card introduced in 1987 (even though its YM3526 was released in 1984, 3 years earlier). This quickly became famous for adding 'toy synth keyboard' music to PC games, which PC users fawned over.

[rzookol]

Originally Posted by Bruce Abbott

If we ignore the C64 and Amiga, what was the first home computer of note to have a better sound chip? The first PC card with FM synthesis was the Adlib card introduced in 1987 (even though its YM3526 was released in 1984, 3 years earlier). This quickly became famous for adding 'toy synth keyboard' music to PC games, which PC users fawned over.

Apple 2GS with Ensoniq sound chip


[ Show youtube player ]

[ImmortalA1000]

@Bruce Abbot
What Bob Yannes wanted to do was add higher fidelity into the design, more components for extra filters/oscillators etc. This all needed a larger surface area for the chip, which the original VIC-II and SID of 1981 for the abandoned Commodore 'arcade motherboard' project were designed within very strict limits to keep down manufacturing costs. The SID was complete before the VIC-40 AKA C64 project was started. It would have cost a fortune to re-design a compatible C64 replacement to host it and significantly more to manufacture. Engineers always want to make better stuff, it's an ego thing, but just like a 5L V8 engine is more powerful than a 2.5L V4 it also costs more to manufacture and so costs the consumer more. The SID was good enough for the C64, it was the best of everything else money could buy even in 1984 for a home computer/console so Jack didn't see the point. You already have world class synth on a chip in your machine that is undercutting Atari 800 and Apple II was his attitude.

The 'bug' was not an issue, it's just a slight click when you set the SID global volume to 10 or 15 from zero. What they did was destroy the ability of the SID to make 5 channel sound (2 virtual sample channels and 3 waveform channels in Mega Apocalypse) and classic big selling games sound goofy/broken on the 64C and were never fixed even when on budget re-release. They also cut down the bass so the epic trademark SID resonance/filtered explosions of things like Blue Max are a less than 'epic' too. Commodore were meddling, they didn't fix anything. It's a bit like fixing a window that won't open by smashing it, yes you have 'fixed' the problem but you created even more. That is really the point, hence the quotes round certain words

For the 64C Commodore also messed with the video output quality, they improved the gamma (brightness/contrast) of the image output to composite/RF output BUT they also ballsed up the colour decoding (for PAL anyway, don't have NTSC models or CRT TVs to test as I live in the EU) so they introduced a new problem of chroma cross talk (it's like a dithered line of pixels around all the graphics between background/forground colours) except where you have red/light red or green/light green and blue/light blue (or grey scales) so again it was a complete waste of time, you can fix the gamma issue by passing the C64 RF output through a £10 signal booster people with indoor aerials for TV reception would use back then anyway.

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The YM2149 sound is highly simplistic for a £750 computer in 1985 compared to the SID in a £200-250 C64. Hence the thread. By 1987 when the £299.99 520STFM cost the same as the 128 Amstrad CPC with AY8192 it was fine In the grand scheme of things the AY8192/YM2149 is not great as a sound chip.

The Atari ST got a disk controller that happens to make some sounds, it's not just the price of the YM chip vs other things, Atari used the YM for many functions on the ST motherboard and it was always meant to go down to £399.99 with a modulator half a year after launch, that was Atari's roadmap as such. It does sort of make sense until you realise there are no 'budget' MIDI sound modules, this area is where the big boys with big budgets play not home computer owners. Still, to their credit, the YM sfx + General MIDI sound module for music combined is not really any worse than original soundblaster+Roland LAPC1/MT32 combination PC gamers used in the early 90s. There are about 50 games that do output general MIDI music on the ST and it's quite a nice combo but it puts the price of the 520STM/STFM far in excess of the price of even the launch year A500 of £500 + £25 A520 modulator so it's not really an option. If you had £900 to spend on a home computer.

For music studios it was great because the built in MIDI ports created some very nice sequencing software for the ST before the Amiga 500 was on sale so they cornered the music studio market. The MIDI ports just never really made any difference in the ST vs Amiga vs Archimedes battle for home computer sales in the 80s really.

[pandy71]

Originally Posted by rzookol

Apple 2GS with Ensoniq sound chip

Nope - 5503 is not a good choice for system like Atari - can't be easily integrated in UMA systems like ST, need or fancy glue logic or significant bus load and stealing CPU cycles. In Apple IIGS it use dedicated RAM so similar approach in ST will add only more IC's to already crowdy design...

Atari could integrate sound like AY/YM with one of custom IC's but still need two 8 bit I/O ports. So YM with additional even single channel PCM (even PWM fully digital implementation in for example MMU) could be OK combo.

[ImmortalA1000]

Leonard Tramiel states the ST was always meant to launch with a blitter chip, probably explains why the ROM routines for the A-Line/Line-A graphics are so badly optimised (hence a £30 'software blitter' will give you Mega ST speeds on a 1985 520ST when using GEM), but he has never really mentioned anything about non YM2149 sound. The much better Yamaha MSX exclusive YM chip is a rumour (think OutRun arcade quality music). AMY was a pipe dream from some engineers in no rush or no idea about realities of commercial costs and POKEY wasn't going to be enough and probably cost more than a couple of low end DACs shoehorned into the design. I think it was a cost cutting measure too far not to have a couple of low end 8bit DACs in there to complement the simplistic sounds of the 2149. The idea of MIDI is fine but unless you can get 'home computer market' priced MIDI sound modules it becomes useless outside the semi-professional and above market.

Esoteric waveform based sound chips are fine but the future was always DAC based, first Lorraine prototype quickly followed by Archimedes prototype with double the number of sample based audio channels as Amiga 1000 AND software panning for each channel effectively quadruppling the Amiga's potential in certain situations. PC's eventually went to multiplexed stereo 16bit DAC method. I think 1984 Mac had a single DAC too.

Whoever designed the £10-15 DAC based Amiga MOD playback capable sound cartridge for Ubisoft's B.A.T. shows what should have happened, Atari needed to do this STE exceeding cheap solution 18-24 months before Ubisoft's 1989 game it came bundled with. Given the sorts of volumes Atari would purchase for manufacture THIS is what they should have done and that's really where the story ends.

A talented music programmer can replicate a waveform based system using enough DACs and DMA/CPU cycles. This does not apply in a vice-versa type situation. I think a couple of DACs on the £750 520ST complete system bundle was the way to go, it was meant to be a Mac killer hence the name Jackintosh BUT somebody forgot to check the audio specs for the Mac. The YM2149 noises should always have been an extra freebie and not the only method of generating audio, twin DACs + 2149 is probably how it should have been from the start, at the very least one DAC and hardware multiplexing as used in the 128k Mac. Imagine how many sales of the 520STM/STFM could have been made to people who owned computers in 1985 without a simplistic soundchip. I know the 2149 really put me off but there was nothing better at the time, the PAL A1000 had only just come out in Germany and prices were 250-300% those of the 520STM bundle I got, which was already at the top end of 'home computer' price range.