BBC Micro SID Tunes

[Negative Charge]

BBC Micro SID Tunes 1

Hi all. I’ve been working on an approach to convert C64 SID tunes over to the BBC Micro’s SN76489 without the need for additional hardware. These are conversions rather than emulation of the SID, and hence lack the more complex SID effects/filters.

It should (in theory) run on an unexpanded BBC Model B and up, but I’ve only Hoglet’s FPGA implementation on the Spectrum Next to test with (plus emulators) so your mileage may vary.

The UI is functional but basic (menu borrowed from another program). I’d love to add some visualisations, but unlikely to find enough time for that. You can follow the journey over on my Twitter feed.

Emulation: https://bbc.godbolt.org/?autoboot&disc1 ... nes-01.ssd

Download for hardware: https://negativecharge.github.io/files/ ... nes-01.ssd

I’ve borrowed @simondotm’s VGC player for this as they’re big tunes that need high compression: https://github.com/simondotm/vgm-player-bbc

[jms2]

I have had a try in BeebEm and B-Em and it sounds pretty amazing in both! Some tunes are slightly "crackly", but I wonder if this is just an emulation effect. I'll have a go on a real Beeb later and let you know how it goes.

[Negative Charge]

I have had a try in BeebEm and B-Em and it sounds pretty amazing in both! Some tunes are slightly "crackly", but I wonder if this is just an emulation effect. I'll have a go on a real Beeb later and let you know how it goes.

Thanks! The conversion process is inherently lossy due to the vast differences between the SID and the SN76489. Sawtooth, triangle, high/low/band pass filters, ring modulation effects are difficult, if not impossible, to reproduce and the frequency range difference is an issue too. The result is that in some tunes the clipping / lack of effects manifests itself as cracks and pops. Some tunes are dramatically better than others. As the conversion process is refined I’m sure this will become less noticeable. I think implementing software bass may help with some of the clipped lower frequencies.

Very interested to hear if there’s any difference on real hardware. The emulators sound reproduction is pretty faithful, so I would expect some/all of the conversion artefacts to remain.

[jms2]

Well, you'll be glad to hear it does sound a lot better on real hardware. It's hard to quantify, but using Monty on the Run as a reference I think about 75% maybe of the crunchy noises are no longer audible, and those that remain are less noticeable.

I have not listened to all the tunes mind you, that's because my real machines are in the attic room and its over 30 degrees up there!

I'm particularly interested in this because I'm currently gathering the components needed to build up my Electron Sound Expansion cartridge, which basically adds an SN76489. It also comes with 8k RAM and 8k ROM, hardly any of which is used, so I have aspirations to put the VGM player up there alongside the OS sound processing code.

[Negative Charge]

That’s good to hear! Thanks for testing. B-em and b2 in general seem to reproduce the sound better than beebem. I’ve been looking out for a second generation Electron Sound Expansion cartridge myself, but they appear to be rare beasts to find on the second hand market. I think making one myself from the schematics would be beyond my capabilities unfortunately.

[jms2]

If my design works, and you are ok with soldering, I can send you one.

[Negative Charge]

Thanks for the kind offer. I can just about work my way round a soldering iron. Very interested to see how you get on with it. I still have plans in the works to get better sound out of the native Elk ULA, but have got a bit distracted by the Beeb at the moment.

[Arcadian]

Goodness, these tracks sounds superb. Really worthwhile project this, are more compilations in the pipeline?

[Negative Charge]

Thank you! I’m converting as many of the tracks that I enjoy as I can, and will include those that turn out okay. Some tracks, especially those by Martin Galway, are well beyond the capabilities of the current conversion process and I can’t do them justice.

Disc 2 is already underway, and I’m open to suggestions for tracks to include on future discs if you have any favourites.

[Pernod]

and I’m open to suggestions for tracks to include on future discs if you have any favourites.

I could make a lengthy list but I don't think you've done Crazy Comets and Zoids yet.

[anightin]

Awsome bringing SID to the Beeb without the SID hardware!

I'd love to hear:

• Rambo Frist Blood Part II

• Giana Sisters

• Parallax

[Negative Charge]

and I’m open to suggestions for tracks to include on future discs if you have any favourites.

I could make a lengthy list but I don't think you've done Crazy Comets and Zoids yet.

Please do! Crazy Comets and Zoids should make disc 2 as there’s space. Rob Hubbard’s tracks can be a bit hit and miss ass to whether they’ll convert to the SN76489, but these seem to be okay representations.

[Negative Charge]

Awsome bringing SID to the Beeb without the SID hardware!

I'd love to hear:

• Rambo Frist Blood Part II

• Giana Sisters

• Parallax

Thank you! You’ve picked three very tough ones there, so no guarantees but I’ll give them a go. Any specific subtunes in those SIDs?

[anightin]

Awsome bringing SID to the Beeb without the SID hardware!

I'd love to hear:

• Rambo Frist Blood Part II

• Giana Sisters

• Parallax

Thank you! You’ve picked three very tough ones there, so no guarantees but I’ll give them a go. Any specific subtunes in those SIDs?

Since you ask, the title theme for Parallax for me is just mesmerising

https://www.youtube.com/watch?v=rVZ2zfXlVSk

[Negative Charge]

BBC Micro SID Tunes 2

14 more conversions from the C64 SID to the BBC Micro’s SN76489.

Emulation: https://bbc.godbolt.org/?autoboot&disc1 ... nes-02.ssd

Download for hardware: https://negativecharge.github.io/files/ ... nes-02.ssd

[Negative Charge]

Since you ask, the title theme for Parallax for me is just mesmerising

https://www.youtube.com/watch?v=rVZ2zfXlVSk

That’s a tough one without a means to effectively simulate SID filters. It’s one I keep coming back to as I revise the conversion technique. I’ll put it down for disc 3, but it all depends on the output and whether I can squeeze an 11m25s track into memory.

[anightin]

Since you ask, the title theme for Parallax for me is just mesmerising

https://www.youtube.com/watch?v=rVZ2zfXlVSk

That’s a tough one without a means to effectively simulate SID filters. It’s one I keep coming back to as I revise the conversion technique. I’ll put it down for disc 3, but it all depends on the output and whether I can squeeze an 11m25s track into memory.

Absolutely no pressure, keep up the great work -- really enjoying these

[Negative Charge]

Absolutely no pressure, keep up the great work -- really enjoying these

They’re in for disc 3… Parallax loses a lot of the definition due to the lack of filters but all 11mins+ are there, and Great Giana Sisters is without the digi drums, but sounds okay:

[anightin]

Absolutely no pressure, keep up the great work -- really enjoying these

They’re in for disc 3… Parallax loses a lot of the definition due to the lack of filters but all 11mins+ are there, and Great Giana Sisters is without the digi drums, but sounds okay:


B3B86C22-3DB0-492D-A3AB-138194561DAF.jpeg

Wow that's fantastic!!

[anightin]

If my design works, and you are ok with soldering, I can send you one.

Happy to build one for @Negative Charge when available

[Diminished]

No idea if it's feasible, but how about Jon Dunn's Ocean Loader 4?

[Negative Charge]

BBC Micro SID Tunes 3

14 further conversions from the C64 SID to the BBC Micro’s SN76489.

Emulation: https://bbc.godbolt.org/?autoboot&disc1 ... nes-03.ssd

(If using B-em, switch off the internal sound filter. With b2 make sure you’re using a very recent version. JSBeeb sounds okay)

Download for hardware: https://negativecharge.github.io/files/ ... nes-03.ssd

[Negative Charge]

No idea if it's feasible, but how about Jon Dunn's Ocean Loader 4?

I’ve given Ocean Loader 5 a go (posted on Twitter a week or so ago). I can try 4, but I think it didn’t sound so good when I last tried. Tools have been updated since, so may be better.

[Negative Charge]

If my design works, and you are ok with soldering, I can send you one.

Happy to build one for @Negative Charge when available

Thank you for the kind offer. Now that I have an FPGA Beeb, I’ve less use for this expansion than I did previously, but interested to see how this one works out.

[Diminished]

No idea if it's feasible, but how about Jon Dunn's Ocean Loader 4?

I’ve given Ocean Loader 5 a go (posted on Twitter a week or so ago). I can try 4, but I think it didn’t sound so good when I last tried. Tools have been updated since, so may be better.

I prefer 4, although 5 is very similar anyway. I've been thinking a bit about attempting a cover version of it, but the slap bass part is ... not easy to play live.

The Beeb version actually sounded better than I expected. Not bad at all!

This may be timely, since a turbo speed tape loader for the Beeb and Electron has just been invented, and ... uh ... well, it could really do with a front-end, you know?

[Negative Charge]

Another 14 conversions from the C64 SID to the BBC Micro’s SN76489.

Emulation: https://bbc.godbolt.org/?autoboot&disc1 ... nes-04.ssd

(Best in JSBeeb, recent B-Em (internal sound filter disabled) or b2 builds)

Download for hardware: https://negativecharge.github.io/files/ ... nes-04.ssd

[Negative Charge]

BBC Micro SID Tunes 5

Even more conversions from the C64 SID to the BBC Micro’s SN76489.

Emulation: https://bbc.godbolt.org/?autoboot&disc1 ... nes-05.ssd

(Best in JSBeeb, recent B-Em (internal sound filter disabled) or b2 builds)

Download for hardware: https://negativecharge.github.io/files/ ... nes-05.ssd

(Note: I’m still trying to work out the cause of the brief blip of static before each track plays. It might be reading non-tune data, but need to trace this further)

[fwibbler]

Can you do one with all of the C64 R-Type music (I mean all the levels)?

[Negative Charge]

Can you do one with all of the C64 R-Type music (I mean all the levels)?

I think I can manage that: https://bbc.godbolt.org/?autoboot&disc1 ... _music.ssd

[anightin]

Have just seen this on the Acorn Computer and BBC Micro FB page:

The Register promoting a music composition competition at the TNMOC:

https://www.theregister.com/2021/07/27/ ... nERksct2q8


Sending your conversions to them should definitely inform them that the Beeb is better than just "bleeps, whistles, and flatulent squawks"


The actual TNMOC competition page is here:

https://www.tnmoc.org/retro-sounds-musi ... tion-entry