Paula is a plain D/A chip with two butterworth filters. It doesn't offer anything special. The SID has custom and rare "faulty" chip die with a special sound.
And hey, Paula as well has its own particular character (thanks to the gritty early digital sound tamed by a bit of filtering,) even if it is just a sample-playback affair.I keep reading that, but I sure don't hear it when I playback CD audio in 14bit at 44Khertz. The only thing I hear is some noise in very soft parts of the music.
Oh pshaw. The SID will blow any generic-ass wavetable GM box completely out of the water for sheer sonic character. Hell, even Yamaha's old FM chips would outshine the generic XG crap they poop out now, if used well. And hey, Paula as well has its own particular character (thanks to the gritty early digital sound tamed by a bit of filtering,) even if it is just a sample-playback affair.
But it's silly to think that it'd be worth the trouble trying to create a dedicated module version; for one thing, as freqmax points out, Paula itself is only DACs and filters, and requires Agnus to actually get its data. For another, you need a system to load samples into memory, interpret incoming MIDI events, assign channels, and apply effects like volume envelopes anyway. At that point, you're already halfway to an Amiga.
I keep reading that, but I sure don't hear it when I playback CD audio in 14bit at 44Khertz. The only thing I hear is some noise in very soft parts of the music.I'd count that as a bit different, though, since the 14-bit trick is circumventing one of the chief aspects (the 8-bit sample depth) that adds that grit in the first place, and software mixing is going to resample everything to the master sample rate, possibly with interpolation, as opposed to the varying rates and lack of interpolation used when playing back samples on individual channels. (Also, if it's on an ECS/AGA machine, it's maybe running at a higher maximum sample rate, which would affect it as well.) All told, you're working around a number of things that non-AHI audio does to the signal.
MT32 is still the best :)The MT-32's pretty great alright :) Even if I have been a bit spoiled for lesser Roland LA synths by getting to play a D-50...
The PhoenixSID 65X81 (http://www.myhdl.org/doku.php/projects:phoenixsid_65x81) project (2006) aimed to faithfully create the SID sound using modern hardware. The workings of a SID chip were recreated on an FPGA, based on interviews with the SID's creator, original datasheets, and comparisons with real SID chips. It was distinguished from similar attempts by its use of real analog circuitry instead of emulation for the legendary SID filter. However, the project was discontinued, because George Pantazopoulos (http://www.myhdl.org/doku.php/users:george_pantazopoulos), who was the head of this project, died on April 23, 2007, at the age of 29.
I'd count that as a bit different, though, since the 14-bit trick is circumventing one of the chief aspects (the 8-bit sample depth) that adds that grit in the first place
All told, you're working around a number of things that non-AHI audio does to the signal.
It's also possible that my perception of the "Amiga sound" is affected by the speaker characteristics of the 1084, but I recall it being pretty noticeable over external speakers as well...
With a some tinkering and soldering the Amiga could be wedged internally into a controller midi controller keyboard, and used for sample reply via midi - although an external LCD display or monitor+mouse would still be needed to choose samples and so on through a suitable programme.
I think this is a common misunderstanding; people don't realise Paula is just a sample playback chip. They hear it produce 'chip' music and assume it's being synthesised - it's an easy mistake to make.
If it ain't better than a FPGA + D/A then it's not worthwhile. Said combination can also do filters in the digital domain. And at that point the Amiga custom chip loose.Depends. Filters are tricky beasts that impose their own particular character on a sound, and they're rarely identical just for having the same basic specs. The 12db/oct. low-pass filters in my Matrix-6, my JX-10, and my MS-20 Mini don't sound at all the same, even when you don't have the resonance cranked up. Nothing in all the world but a Moog filter sounds like a Moog filter (except for the various naked clones of the Moog filter that were kiboshed for patent infringement!) It's probably possible to come up with a good emulation of the Amiga's filter, but it's not as simple as just "oh, digital filter, 12db, done."
Sure, but all 8bit samples, regardless of hardware, will sound like that.Yes, but again, it's only one part of the equation.
Well, I'm not using AHI (don't have it installed), and play CD audio back with Hippo player. The only non-standard thing here is the playback rate of 44Khz (using a 31Khz screen mode). It's still Paula playing a few samples with DMA however (and Paula can go much faster than DMA), so I'm still not convinced ;)Well, you're still circumventing the 8-bit aspect, and you're also doing playback at 44KHz instead of x-28KHz, both of which bring the sound much closer in line with modern specs. Of course that's gonna sound different than a game playing back 8-bit samples at varying, sub-28KHz rates.
Perhaps it has something to do with it. My Amiga is connected to an amp with reasonable headphones, and when I listen to CD audio, I just hear sound that sounds almost the same as what my peecee produces. Back in the day they used to say the Amiga has CD quality sound. Turns out to be almost true.Oh, I have run mine through proper speakers, and it's plenty nice. I just find that, for classic games and vintage MOD playback at least, I kinda like the things that are done to the sound by the 1084. It sounds right, to me.
Anyway, you've gotta use an amp with proper speakers or phones for your Amiga. Those internal monitor speakers do the thing justice ;)
Sure, but all 8bit samples, regardless of hardware, will sound like that.
Well, frankly neither is anything special.
If I was building a retro system today, I'd use a cheap Yamaha sound chip with wavetable capability and Midi support.
Frankly, Commodore fanatics have always dismayed me.
I mean, get over it guys, the 6502/6510 was a pretty lousy processor.
I think this is a common misunderstanding; people don't realise Paula is just a sample playback chip. They hear it produce 'chip' music and assume it's being synthesised - it's an easy mistake to make.
If you want to recreate that 8 bit sound an old dedicated sampler like an Akai S2000 would do this 'out of the box'
Regardless of what others may say - the SID chip is unique. There weren't any pre-built synths that could sound anything like it; it was worthy of development into the SidStation.
Paula can do:
Sample playback.
Loop playback - it's an oscillator.
If the 68K changes the waveform it's looping you get wavetable synthesis (think PPG synths).
Modulation of channels with AM and/or FM so:
- FM synthesis.
- AM synthesis.
- FM + AM synthesis.
Non-DMA playback. The processor to produces waveforms on the fly any way it pleases - You could set up the Amiga as a soft synth before soft synths were invented!
Oh pshaw. The SID will blow any generic-ass wavetable GM box completely out of the water for sheer sonic character. Hell, even Yamaha's old FM chips would outshine the generic XG crap they poop out now, if used well. And hey, Paula as well has its own particular character (thanks to the gritty early digital sound tamed by a bit of filtering,) even if it is just a sample-playback affair.
But it's silly to think that it'd be worth the trouble trying to create a dedicated module version; for one thing, as freqmax points out, Paula itself is only DACs and filters, and requires Agnus to actually get its data. For another, you need a system to load samples into memory, interpret incoming MIDI events, assign channels, and apply effects like volume envelopes anyway. At that point, you're already halfway to an Amiga.
What definition of the world "special" do you subscribe to, not to include the SID?
I think that if the qualities of the CPU was the question for any of these people, they would have abandoned their platform a long time ago (along with the M68k series).
Actually, its the FM series I am thinking about building into a 63C09E design I am bread boarding.Ah. Good choice. (I've actually got a spare OPL3 combo chip I'd like to build a portable sequencer around one day...)
And as to character, yeah SID sound is identifiable.Well, the SID may not be to your taste, but it certainly is to a lot of people's. It's the closest home computers ever got to a classic subtractive analog synthesizer, even if it's very limited by comparison to those. And it's perfectly possible to add MIDI capability to a C64, or use one of the various SID-based module designs.
I don't know that that makes it more desirable.
And Midi compatibility (which the SID doesn't have) is nothing to scoff about.
BTW - I can tell you DO know what you are talking about, because I would go with an FM over an XG design myself. 2 to 4 meg wavetable in rom or ram?Oy, tell me about it. It's shocking how the best stuff currently on the market is the stuff that either dedicatedly emulates or simply goes back entirely to the technology of the '70s and '80s. I got my Korg MS-20 Mini (a direct recreation of an old analog monosynth) the week before last and I've spent damn near every free moment since playing with it (even while in the middle of a move!) But I tried the whiz-bang Jupiter-80 (an "advanced" modern digital wavetable/modelling keyboard gussied up like the classic JP8, which it doesn't sound a thing like) at my local music store and got bored of it after three minutes. Somehow things went terribly, terribly wrong when ROMplers became the dominant species of synthesizer...
Yeah, sometimes the older hardware just had more capability.
Unfortunately, as processor have become more powerful, sound chips have kind off de-evolved.
The AC'97 spec is a joke.
Didn't Musicline Editor do actual realtime synthesis using Paula?If that featurelist is accurate, yes. For a 68k-based softsynth, that's impressive - resonant filters and effects? Hell, a lot of hardware ROMplers didn't even have that.
http://www.musicline.org/software.html
What's so bad about the AC97 spec?It's provided a mediocre standard for computer audio to uniformly adhere to and never bother with striving to improve on or add interesting new facets to. (At least until you get into overpriced pro-audio gear.)
and what makes OPL3 so good?It's a versatile synthesizer chip capable of a wide variety of rich, interesting sounds, and has the distinctive Yamaha FM character. You'd never mistake it for anything else.
What's wrong with ROMplers?Nothing's inherently wrong with ROMplers, but by the mid-'90s they had, kudzu-like, almost completely overtaken the landscape, from the bottom-end cheap Casio crap to high-end digital pianos and "workstation" keyboards. This is a problem because ROMplers are just plain not in the slightest bit organic; you press a note at a given velocity with a given patch, you get the same damn sound every time. Whereas even the DX7, while just as purely digital, lets you add subtle touches (like the capability for any of the six oscillators to be free-running) that differentiate each note from the next in an analog kind of way. ROMplers have their uses, but as the be-all and end-all of sound synthesis that they've become, it's Spam, Spam, Spam, Spam, Spam, Spam, Baked Beans, Spam, Spam, Spam and Spam. Just way the hell too much Spam.
Btw, I feel that it weren't until the 90's that artists learnt to make good use of synthezisers.Allow (http://www.youtube.com/watch?v=3yar10vUjcc&t=7m45s) me (http://www.youtube.com/watch?v=6Q00HQwO2Sg) to (http://www.youtube.com/watch?v=fFjtxDfrjB0) prove (http://www.youtube.com/watch?v=fpWNimba344) you (http://www.youtube.com/watch?v=dmzDUYR90O8) completely, (http://www.youtube.com/watch?v=8NPJ6GMXM3E) utterly (http://www.youtube.com/watch?v=W1oaXqBJRRQ) wrong. (http://www.youtube.com/watch?v=fYprIlvoJy4&hd=1&t=5m22s)
If that featurelist is accurate, yes. For a 68k-based softsynth, that's impressive - resonant filters and effects? Hell, a lot of hardware ROMplers didn't even have that.
The music industry at large has never known its ass from its elbow, man. When Chuck Berry was ripping it up on the crazy new distorted guitar and Little Richard was shrieking like a maniac, the music industry was employing Pat Boone to make that music safe for easily-frightened old white grannies. Nowadays the music industry thinks that you can make a singer by grabbing some skank off the street and running her through auto-tune. "The music industry at large" is the last place you look for actual talent in music.
A sufficient computer audio standard shouldn't be a standard at all, basically. There should be some basic standard capabilities, but manufacturers should be encouraged to color the results in interesting ways, with interesting (optional) effects, and we should bring back MIDI as a default method for music delivery. Back in the day, when each sound card had its own way of rendering MIDI, you could actually get different sounds out of them. If you didn't like the sound of an OPL2 sound card, you could get a GUS, or an IBM Music Feature Card, or hook up to an MT-32 through an external MIDI connection. Each of those would sound very different, and you could pick one that you liked. Now it's all the exact same stuff in MP3 recordings, and where there is MIDI, it's that same wretched Roland soundfont that comes with Windows. Yuck.
didn't mean to piss you off,.
At the time it was produced the SID was pretty remarkable.
Compared to the 6502 its a work of art.
The 6502 is little more than an attempt to undercut 6800 pricing.
The design holds no attraction for me.
And if we have all stopped use old processor like the 68K, how come I can still use 68K machine code under MorphOS?
And believe me, its being done. New code.
Because its still backward compatible.
We are just a really stubborn bunch.
I've seen people take SID chips and create little synth boxes to be controlled via MIDI. Seems a lot of people are willing to pay a nice amount to have such a thing.
So I'm wondering, how come nobody seems to be doing this with the Paula chip? Also has the Paula chip been cloned?
The music industry at large has never known its ass from its elbow, man. /../
A sufficient computer audio standard shouldn't be a standard at all, basically. There should be some basic standard capabilities,
Lets put it this way, any music you could access by listening to radio or buying records. There were even special shops for those weird "imported records" for people that wasn't satisfied with the industry marketed and spoon fed stuff. It took until the 90s before they presented synthesizer music that was good.
Cubase 64 :)Amazing :D
http://www.youtube.com/watch?v=MDrqBYkco-Y
CU Amiga Magazine announces 'Project XG'
CU Amiga Magazine continues its proactive assault on bringing the best products and technology to the Amiga market, backing up its reputation as the World's Best Amiga Magazine.
Announcing Project XG, a DIY feature to build an 18-bit 48Khz external sound card based on the Yamaha DB50XG. It will cost under £130 pounds Sterling (GBP); a full parts list, suppliers and detailed instructions on construction will be provided. Even stylish artwork for the box is included!
Project XG will offer extremely high quality audio with real time DSP effects on any or all of the 32 instruments it can play at the same time. Project XG is a MIDI module with some 676 ultra high quality instruments and some 21 drum kits built in. The DSPs manage 11 types of Reverve, 11 types of Chorus and 42 types of Variation. The lack of being able to play custom samples is solved by mixing the Amiga's audio into that of the Yamaha's.
Whether full MIDI sequencing or straightforward playback of General MIDI and XG MIDI files is desired, Project X will cope better and sound better than any PC sound card in common use. To say the least.
Naturally the corresponding cover CD-ROM will be loaded to the brim with General MIDI and XG MIDI songs, MIDI sequencers and a wealth of other support software. It will also contain audio tracks to demonstrate the quality of the output compared to Amiga output. (A/B comparisons) CU Online will soon also host some MPEG Audio Layer III files.
CU Amiga Magazine hopes to aid the establishment of XG MIDI in Amiga software such as music applications, games and such forth. Initially with this economical DIY project and then following commercial efforts; Project XG is a campaign to bring this high quality audio standard to the Amiga. Project XG will put the Amiga back on the music map!
References: Yamaha's XG home page http://www.yamaha.co.uk
Christian Bauer's GMPlay General MIDI and XG Player.
Cool thread guys, I saw reference to Yamaha stuff so wanted to tell you guys I have one of these boxes "The Amiga Project XG"
Id also like to say that anyone here that is saying they can get the "amiga sound" through emulation on a pc is full of CRAP. They must be tone deaf. Sure you can "prove" it with technical theories and whatever else, but take it from me djng for over 20 years the Amiga Paula HAS A SUPER PHAT SOUND hook it up to a good mixer and speakers and feel the base. Perfect for electronic/hip hop. The low end bass is out of sight.
Not the same sound, BETTER sound using any old Win XP laptop costing $50 and a copy XMPlay. The only unusual thing about my setup is it's sitting in my home cinema and the music is sent digitally to the amp so it is the purest possible sound of what the MOD is supposed to sound like before the cheap ass components on the A500 motherboard destroy the quality even more.
People who think a real Amiga playing a MOD sounds as good as XMPlay on a PC are tone deaf (usually in the tones from about 8khz to 20khz deaf actually lol). Signal to noise ratio on a real Amiga is terrible, total harmonic distortion is about the same as a 1978 Alba/Binatone clock radio and the hard separation of channels 1,3 and 2,4 with no possibility for even 1% cross fading all go to making MODs sound worse on a real Amiga....and that's before you even talk about pre-amp tweaks to the frequency spectrum and smoothing of 8bit samples to pseudo 16bit samples (which is actually what the Ensoniq 8bit sample keyboards of the late 80s did...and as they were all designed by Bob Yannes the designer of the SID and the IIGS awesome synth chips you can bet your ass there is a good reason for this upscaling of 8bit samples).
A simple test is either the Level 1 music for Super Stardust or the intro on It Came from the Desert, play it on a real Amiga linked to the line input on the same amp and again on any old Win XP PC playing the same MODs attached to the same amp via a coax/TOSlink cable to the digital input line.
Emulation of the computer as a whole will never come close to the frame accurate code running on Daphne/Agnus I agree but MOD playback is something PCs were doing better since the start of the century with standalone players so Paula IS technically nothing special at all, only the creative talents of the people who used it well and the genius decision by Jay/RJ/Dave to stick a 4 channel DAC on the motherboard of Lorraine :)
Cool thread guys, I saw reference to Yamaha stuff so wanted to tell you guys I have one of these boxes "The Amiga Project XG"Eh. Unfortunately, by the time Yamaha developed their XG standard, they'd gone entirely into ROMpler territory, playing the same sets of samples from ROM (downsampled to lower rates on the cheaper instruments) on basically everything, sacrificing pretty much any potential for sound creation in the name of "realism." Bleah. Their FM synths (or even their ROMpler/FM hybrid synths like the SY77) were much more interesting.
Amiga can do pretty nice sounding SID renditions (Per Hakan Sundell's C64 Demo for Amiga OCS and his SIDPlay app sound excellent...he also wrote C64S DOS emulator).The renditions I've heard on the Amiga are nice in the sense that they sound good, but they're only kind of reminiscent of the SID, and nothing you'd ever mistake for the real deal. Then again, I haven't kept up on the Amiga side of SID emulation for a while...
The problem with having a traditional soundchip is they have a distinct sound.Whether that's a problem or not largely depends on what you want out of an audio device. If you want flawless reproduction of a pre-defined sound, then yeah, you're not going to want a synthesizer chip - what you'd want is the highest-quality DAC/aliasing filter combo you can get and enough memory to store a good recording of the sound. But for those of us who want an instrument, that's a silly complaint to make. You wouldn't gripe if you bought an acoustic piano and found that it was incapable of sounding like a Hammond organ; that would be silly. The AY chips didn't suck because they had a distinct character, they sucked because they were capable of exactly two kinds of sound (square waves and noise,) and there's just only so much you can do with that. Whereas the SID is much more capable, but still distinctive and full of character.
Having said that SID is a genuine analogue synth on a chip and that is the key to why it is such an awesome piece of kit to design things for. If you look how much 1980 mono synths with similar technology cost you will not call a $20 6581 chip over priced ever again IMO :)Well, I wouldn't stack the SID up against higher-priced monosynths - it doesn't get quite the full organic, analog feel because its oscillators are digital, the ring mod and oscillator sync are rather lackluster, and the filter resonance doesn't even get close to self-oscillation. (Though it has its own advantages - there's surprisingly few synths that can do PWM with a center point other than pure square, or provide anything like the noise + pulse combo waveform. It'd certainly be a lot closer contest against single-oscillator budget monosynths like the SH-101, where it could compete on sound and deliver polyphony.) But yeah, it is pretty dang incredible how much Bob Yannes delivered in one little chip for a low-cost home computer :)
Biggest problem with SIDs IMO are that no two even from the same revision sound exactly the same ie two 6581 revision 3 chips may sound different even in the same machine...a subtle difference but with games that use complex filtering effects it can be noticeably different.Au contraire, that's part of the beauty of analog gear ;)
Not the same sound, BETTER sound using any old Win XP laptop costing $50 and a copy XMPlay. The only unusual thing about my setup is it's sitting in my home cinema and the music is sent digitally to the amp so it is the purest possible sound of what the MOD is supposed to sound like before the cheap ass components on the A500 motherboard destroy the quality even more.All depends on what you define as "better." A lot of us like that sound, however much it might make audio snobs shudder.
That means there's more than plain D/A and standard analog filter. So could anyone describe what's special in technical terms?"More than" a DAC and filter, no. But again, even a system with just a DAC and filter can have its own distinct character, because those components color the sound in their own ways. No electronic component, especially no analogue electronic component, is actually a mathematically ideal implementation of its nominal function. As has been noted, the Amiga's DACs aren't even close to linear - that's going to distort the output. Also, samples are fed in at varying rates and played back without interpolation, which means that any aliasing noise is going to come out at a different frequency, likely well within the range of human hearing, which is also going to color the sound.
That means there's more than plain D/A and standard analog filter. So could anyone describe what's special in technical terms?
(oh and what technically made C64 ceramic SID special would be interesting too)
It's pretty brute-force, I didn't have time to be elegant. Each "voice" consisted of an Oscillator, a Waveform Generator, a Waveform Selector, a Waveform D/A converter, a Multiplying D/A converter for amplitude control and an Envelope Generator for modulation. The analog output of each voice could be sent through a Multimode Analog Filter or bypass the filter and a final Multiplying D/A converter provided overall manual volume control.
As I recall, the Oscillator is a 24-bit phase-accumulating design of which the lower 16-bits are programmable for pitch control. The output of the accumulator goes directly to a D/A converter through a waveform selector. Normally, the output of a phase-accumulating oscillator would be used as an address into memory which contained a wavetable, but SID had to be entirely self-contained and there was no room at all for a wavetable on the chip.
The Sawtooth waveform was created by sending the upper 12-bits of the accumulator to the 12-bit Waveform D/A.
The Triangle waveform was created by using the MSB of the accumulator to invert the remaining upper 11 accumulator bits using EXOR gates. These 11 bits were then left-shifted (throwing away the MSB) and sent to the Waveform D/A (so the resolution of the triangle waveform was half that of the sawtooth, but the amplitude and frequency were the same).
The Pulse waveform was created by sending the upper 12-bits of the accumulator to a 12-bit digital comparator. The output of the comparator was either a one or a zero. This single output was then sent to all 12 bits of the Waveform D/A.
The Noise waveform was created using a 23-bit pseudo-random sequence generator (i.e., a shift register with specific outputs fed back to the input through combinatorial logic).The shift register was clocked by one of the intermediate bits of the accumulator to keep the frequency content of the noise waveform relatively the same as the pitched waveforms. The upper 12-bits of the shift register were sent to the Waveform D/A.
Since all of the waveforms were just digital bits, the Waveform Selector consisted of multiplexers that selected which waveform bits would be sent to the Waveform D/A. The multiplexers were single transistors and did not provide a "lock-out", allowing combinations of the waveforms to be selected. The combination was actually a logical ANDing of the bits of each waveform, which produced unpredictable results, so I didn't encourage this, especially since it could lock up the pseudo-random sequence generator by filling it with zeroes.
The output of the Waveform D/A (which was an analog voltage at this point) was fed into the reference input of an 8-bit multiplying D/A, creating a DCA (digitally-controlled-amplifier). The digital control word which modulated the amplitude of the waveform came from the Envelope Generator.
The Envelope Generator was simply an 8-bit up/down counter which, when triggered by the Gate bit, counted from 0 to 255 at the Attack rate, from 255 down to the programmed Sustain value at the Decay rate, remained at the Sustain value until the Gate bit was cleared then counted down from the Sustain value to 0 at the Release rate.
A programmable frequency divider was used to set the various rates (unfortunately I don't remember how many bits the divider was, either 12 or 16 bits). A small look-up table translated the 16 register-programmable values to the appropriate number to load into the frequency divider. Depending on what state the Envelope Generator was in (i.e. ADS or R), the appropriate register would be selected and that number would be translated and loaded into the divider. Obviously it would have been better to have individual bit control of the divider which would have provided great resolution for each rate, however I did not have enough silicon area for a lot of register bits. Using this approach, I was able to cram a wide range of rates into 4 bits, allowing the ADSR to be defined in two bytes instead of eight. The actual numbers in the look-up table were arrived at subjectively by setting up typical patches on a Sequential Circuits Pro-1 and measuring the envelope times by ear (which is why the available rates seem strange)!
In order to more closely model the exponential decay of sounds, another look-up table on the output of the Envelope Generator would sequentially divide the clock to the Envelope Generator by two at specific counts in the Decay and Release cycles. This created a piece-wise linear approximation of an exponential. I was particularly happy how well this worked considering the simplicity of the circuitry. The Attack, however, was linear, but this sounded fine.
A digital comparator was used for the Sustain function. The upper four bits of the Up/Down counter were compared to the programmed Sustain value and would stop the clock to the Envelope Generator when the counter counted down to the Sustain value. This created 16 linearly spaced sustain levels without having to go through a look-up table translation between the 4-bit register value and the 8-bit Envelope Generator output. It also meant that sustain levels were adjustable in steps of 16. Again, more register bits would have provided higher resolution.
When the Gate bit was cleared, the clock would again be enabled, allowing the counter to count down to zero. Like an analog envelope generator, the SID Envelope Generator would track the Sustain level if it was changed to a lower value during the Sustain portion of the envelope, however, it would not count UP if the Sustain level were set higher.
The 8-bit output of the Envelope Generator was then sent to the Multiplying D/A converter to modulate the amplitude of the selected Oscillator Waveform (to be technically accurate, actually the waveform was modulating the output of the Envelope Generator, but the result is the same).
Hard Sync was accomplished by clearing the accumulator of an Oscillator based on the accumulator MSB of the previous oscillator.
Ring Modulation was accomplished by substituting the accumulator MSB of an oscillator in the EXOR function of the triangle waveform generator with the accumulator MSB of the previous oscillator. That is why the triangle waveform must be selected to use Ring Modulation.
The Filter was a classic multi-mode (state variable) VCF design. There was no way to create a variable transconductance amplifier in our NMOS process, so I simply used FETs as voltage-controlled resistors to control the cutoff frequency. An 11-bit D/A converter generates the control voltage for the FETs (it's actually a 12-bit D/A, but the LSB had no audible affect so I disconnected it!).
Filter resonance was controlled by a 4-bit weighted resistor ladder. Each bit would turn on one of the weighted resistors and allow a portion of the output to feed back to the input. The state-variable design provided simultaneous low-pass, band-pass and high-pass outputs. Analog switches selected which combination of outputs were sent to the final amplifier (a notch filter was created by enabling both the high and low-pass outputs simultaneously).
The filter is the worst part of SID because I could not create high-gain op-amps in NMOS, which were essential to a resonant filter. In addition, the resistance of the FETs varied considerably with processing, so different lots of SID chips had different cutoff frequency characteristics. I knew it wouldn't work very well, but it was better than nothing and I didn't have time to make it better.
Analog switches were also used to either route an Oscillator output through or around the filter to the final amplifier. The final amp was a 4-bit multiplying D/A converter which allowed the volume of the output signal to be controlled. By stopping an Oscillator, it was possible to apply a DC voltage to this D/A. Audio could then be created by having the microprocessor write the Final Volume register in real-time. Game programs often used this method to synthesize speech or play "sampled" sounds. An external audio input could also be mixed in at the final amp or processed through the filter.
The Modulation registers were probably never used since they could easily be simulated in software without having to give up a voice. For novice programmers they provided a way to create vibrato or filter sweeps without having to write much code (just read the value from the modulation register and write it back to the frequency register). These registers just give microprocessor access to the upper 8 bits of the instantaneous value of the waveform and envelope of Voice 3. Since you probably wouldn't want to hear the modulation source in the audio output, an analog switch was provided to turn off the audio output of Voice 3.
Fair enough, but my point is that to most C64 programmers, the CPU is more or less just a means to an end. The fun stuff is the VIC-II and the SID. The Amiga community seems to have been very CPU-centric, in comparison.
Well, the 68K was a pretty cool processor during a period when X86s were dreadful, and I've gotten a big kick out of the 6809 and the superset in the Hitachi 6309, but I must admit that with its video and sound capability the C64 would have been successful with just about any processor.
Eh. Unfortunately, by the time Yamaha developed their XG standard, they'd gone entirely into ROMpler territory, playing the same sets of samples from ROM (downsampled to lower rates on the cheaper instruments) on basically everything, sacrificing pretty much any potential for sound creation in the name of "realism." Bleah. Their FM synths (or even their ROMpler/FM hybrid synths like the SY77) were much more interesting.
Again, just to nitpick, this is not entirely true, as there are XG implementations based on OPL3 (look at YMF719). XG is no more of a particular sound than General MIDI is, and implementations vary, although I recognize that most were boring romplers.Not really. The YMF719 is a sound-card-in-a-chip combo deal; it only includes the OPL3 for legacy purposes. For its "XG" implementation it's actually got wavetable synthesis capabilities (though I don't know that every YMF719-based sound card used them, since it required external sample memory, and that would've cost money.) By the time the XG standard came around, all of Yamaha's synthesizers were "AWM" (their name for PCM.)
A Hitachi 6309 would have been awesome!
They are still around.
There is even a PLCC 44 pin square version.
The 3 Mhz version can be clocked anywhere between 3.58 to 5 Mhz.
And there are 20MHz versions of the Z-80 and 8MHz (or higher) 6502 and 6502 derivatives.
The eZ80 is very fast and the 32bit Z380 looks rather nice too. Shame it was only ever used in washing machines.
I've worked with the eZ80 professionally, and I say avoid it like the plague if you're planning to use the compiler toolchain.
How was the soundchip "Philips SAA1099" btw?
(speaking of OPL..)
I had bought one of these things:
CMS / Game Blaster.
Perhaps the worst sound card ever.... man did SID really blow that thing away...
http://www.youtube.com/watch?v=VlPJcWf1DeA
fortunately I returned it and got Adlib :)
Oh I had suppressed the evil ear bleeding memories of that abomination!
When I got a GUS to replace mine I was in comparative heaven. :)
I had GUS too.
It was one of those products you just wanted to keep trying to convince yourself how awesome it was because of the raw capabilities and specs and demos, yet the TSR that have it SB/Adlib compatibility was a huge disappointment at a time were native support was extremely lacking.
I ended up selling that card and got the SoundScape 2000. Much better backwards compatibility and even GM :) Also it featured a 68000 CPU which we all know spec-wise, make it totally bada$$ :P
http://en.wikipedia.org/wiki/Ensoniq_Soundscape_S-2000
The Sega Genesis uses one of Yamaha's many four-operator FM chips, so there are actually a number of MIDI modules/keyboards that are essentially the same. The Yamaha FB-01 in particular is pretty much identical in terms of capabilities (minus the ability to play samples and the PSG carried over from the Master System,) with a couple more channels to boot.
Didn't Musicline Editor do actual realtime synthesis using Paula?
http://www.musicline.org/software.html
I know Karlos uses an A1200 controlled by MIDI for sample playback if that counts. Basically an AKAI sampler clone.
Nah, that's software synthesis, made all the more impressive by being able to run well on a basic A1200. IIRC it uses looped wave segments (always powers of 2) as a starting point, much like a chip tune does, though samples are also supported. Instruments are defined using sets of these waveforms that are blended in a variety of real-time controllable ways. On top of that there are software effects such as phasing, low pass resonant filters and so forth. It even has an OctaMED-style 8 channel mode, but you need a bit more horsepower than a stock A1200 can provide to get the best out of it.
Interesting indeed. VST 10yrs before Steinberg. :)
Well, I'm not using AHI (don't have it installed), and play CD audio back with Hippo player. The only non-standard thing here is the playback rate of 44Khz (using a 31Khz screen mode). It's still Paula playing a few samples with DMA however (and Paula can go much faster than DMA), so I'm still not convinced ;)