iiinova — where your digital self keeps evolving

Negative Charge @negativecharge.bsky.social · 26/09/2026

A few updates to the SID emulation on the SN76489. Playback speed is better. I'll put all three players (SoftSID, HardSID & NoSID) up on GitHub soon. Just sorting out the automatic memory relocation to filter out digi tracks these players can't yet handle. 🔊

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Negative Charge @negativecharge.bsky.social · 25/09/2026

Just a small update, but I now have 4x speed SID files dynamically playing on the SN76489. Cycles are very tight so I had to disable the scope and colour cycling, but sounds good. 🔊

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Negative Charge @negativecharge.bsky.social · 21/09/2026

Added in IRQ software bass by default... this is less harsh than using periodic noise via the LFSR. Also improved the scope visualization a little. Still lots of issues with SID files that trample all over the BBC Micro memory map, but this one appears to work just fine. 🔊

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Negative Charge @negativecharge.bsky.social · 19/09/2026

I've posted many C64 SID to SN76489 conversions previously. These are pre-processed register dumps with large memory footprints and need compression / SWRAM. What you're seeing here is actual SID playback with dynamic SN76489 conversion. A game changer thanks to @kieranhj.bsky.social's AKS work.

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Negative Charge @negativecharge.bsky.social · 09/09/2026

Inspired by @kieranhj.bsky.social 's realtime AKS player on the BBC Micro, I reused the AY-3-8912 to SN76489 converter to expand this to realtime playback of PT3 files from Vortex Tracker. This opens up another tracker that can now be used for BBC Micro music composition. Much smaller than ym files.

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Negative Charge @negativecharge.bsky.social · 06/09/2026

A little side project I've been working on... a lightweight streaming ZX02 music driver for the BBC Micro. Supports main memory as well as multiple chunks spread over SWRAM banks. Without giving too much away, the ultimate platform for this driver isn't just the SN76489... more to come 🔊

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Negative Charge @negativecharge.bsky.social · 22/08/2026

A bit of a diversion from SoftSID. I realised that with a few minor changes I could add support for the BeebSID device which interfaces with a hardware SID. Also added a rudimentary menu system and tools to automate the batch relocation of SID files. Should be ready to publish to GitHub soon. 🔊

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Negative Charge @negativecharge.bsky.social · 17/08/2026

Quite a significant improvement in sound quality. SID files are now played back via all three tone channels of the SN76489 all set to play PCM audio. A mass of optimisations allows for a higher sampling rate. 🔊

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Negative Charge @negativecharge.bsky.social · 10/08/2026

Added a rudimentary oscilloscope view to the BBC Micro SoftSID player. It takes up cycles which means I have to drop sampling down to 6500hz, but @pauliehughes.bsky.social SID driver still sounds good on hardware and a sound chip it was never supposed to work on 😊🔊

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Negative Charge @negativecharge.bsky.social · 09/08/2026

Working on getting some of the more complex SIDs playing. Created a Mode 7 version to free up more base memory, and updated the command line parsing to allow loading from any drive. Still some problematic SIDs that relocate to memory regions not writable on the BBC Micro which need recompiling.

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Negative Charge @negativecharge.bsky.social · 07/08/2026

A little more progress on SoftSID for the BBC Micro. Thanks to @kieranhj.bsky.social for testing on real hardware, which highlighted subtle inconsistencies on all emulators... they may sound fine, but the real hardware doesn't like it when you try an over-optimise the writes to the SN76849.

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Negative Charge @negativecharge.bsky.social · 02/08/2026

A little more work on SoftSID for the BBC Micro. More SID files are working now once I realised several want to unpack into memory between &c000 and &8000, so I page in a writeable SWRAM bank if available. Also fixed VBI track playback speed (correcting Out Run) and implemented NTSC support. 🔊

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Negative Charge @negativecharge.bsky.social · 25/07/2026

SoftSID 0.0.6 for the BBC Micro Added ability to specify the .sid file and track number on the command line. Many optimizations to bring the cycle count down too. Should be ready for a preview release soon once I've chased a few more cycles and relocated some more example SIDs. 🔊

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Negative Charge @negativecharge.bsky.social · 21/07/2026

Here’s the complete Monty on the Run SID playing back using SoftSID on the BBC Micro (albeit slightly too slow). Trying to work out what’s causing the high-pitched carrier tone on other emulators - BeebEm is surprisingly the best right now. youtu.be/2Pw7LqgPdTI

youtu.be

BBC Micro SoftSID Experiment

YouTube video by Negative Charge

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Negative Charge @negativecharge.bsky.social · 21/07/2026

BBC Micro SoftSID v0.03 Now working on other emulators, and directly parsing relocated .sid files. This is the track I've always wanted to get playing properly on the BBC Micro. Getting closer.... 🔊

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Negative Charge @negativecharge.bsky.social · 20/07/2026

Just to prove to myself that playback of other SID files via the SoftSID, here's Plastic Pop by Danko 🔊

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Negative Charge @negativecharge.bsky.social · 20/07/2026

SoftSID v0.02 for the BBC Micro This is a bit more like it. Upped the audio rate to 6.1 kHz to match the VIC-20 version. Also re-located the SID to &1100 which was the cause of the random hangs and inability to playback on the Model B due to a DFS clash. I need to relocate a different SID now 😊🔉

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Negative Charge @negativecharge.bsky.social · 20/07/2026

Ever wanted to play Commodore 64 SID tunes on a BBC Micro without needing additional hardware? Having seen similar attempts on the VIC-20, Atari 800 and ZX Spectrum I thought I'd give it a go. Early days, unstable, and sound fidelity needs to be improved, but it works! (sort of...). SoftSID v0.01 🔊

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Negative Charge @negativecharge.bsky.social · 16/07/2026

I previously had a go at converting Tim Follin's 1-bit ZX Spectrum beeper routine for Agent X II to the BBC Micro's SN76489. Here's a follow up attempt with Chronos. The percussion isn't quite right, but the melody is perfectly recognisable. 🔊

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Negative Charge @negativecharge.bsky.social · 12/07/2026

Just to close this one out... random colour palette, screen fades and the odd teapot. Source code at the link below for those interested. I'm sure it can be optimized and even implemented in a better way. github.com/NegativeChar...

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Negative Charge @negativecharge.bsky.social · 10/07/2026

Yes, Mode 1, even with less colours allows for a lot more going on...

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Negative Charge @negativecharge.bsky.social · 10/07/2026

I haven't posted any demos for a long while, so here's a version of 2D Pipes in Mode 2 which works as quite a good screensaver for the BBC Micro. No music on this one as I waste 20kb just on the screen mode. No random teapots at the moment either. It might look better in Mode 1 with square pixels.

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Negative Charge @negativecharge.bsky.social · 05/07/2026

I've replaced the compression with zx02 from lzss, which on average is giving 2kb smaller files. I've also implemented a new SID converter to handle some of the trickier tunes. Doesn't look any different, but I can now squeeze a few extra tracks onto the BBC Micro music disks. 🔊

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Negative Charge @negativecharge.bsky.social · 20/06/2026

Slowly putting together some new music disks for the BBC Micro using a new set of converters. This one demonstrates squeezing a multi channel song down into 3 tone channels and one noise channel. Still some refinement needed. Here's the original for comparison: demozoo.org/music/134849/ 🔊

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Negative Charge @negativecharge.bsky.social · 22/05/2026

Putting the BBC Micro compressed VGM to the side for now as I can't get it to work at the required speed. Instead, I've been looking at some of the Tim Follin archives posted by @breakintoprogram.co.uk to GitHub to see if I can get any of the classic beeper music playing back on the SN76489: 🔊

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Negative Charge @negativecharge.bsky.social · 17/05/2026

While I continue to battle with compressed VGM playback streaming from disk at a decent speed, here's some brand new BBC Micro music by Enfys from Outline 2026. 🔊

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Negative Charge @negativecharge.bsky.social · 11/05/2026

Some progress! I now have compressed VGM files (.VGZ) streaming from disk and decompressing on the fly. How do I know it's working? At the very end of the clip you can make out the GD3 strings. Very close to having a streaming, decompressing, SN76489 VGM playback engine. 14KB expanding to 95KB.

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Negative Charge @negativecharge.bsky.social · 09/05/2026

Buffer size reduced to 2kb which leaves plenty of memory for vgz decompression. 8271 floppy disk controller support fixed. 60Hz VGM playback fine. So now I'll work on a basic streaming decompressor to a ring buffer for VGZ. The window should be 32kb (which I don't have free) but we won't need that.

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Negative Charge @negativecharge.bsky.social · 08/05/2026

This took a lot more effort than I thought it would, but after three rewrites I finally have the VGM files streaming directly from disk, being parsed and played back with no noticeable stalling. This is a 125kb VGM that wouldn't fit in the BBC Micro's standard 32kb. Next... on the fly .vgz inflate.

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Negative Charge @negativecharge.bsky.social · 28/04/2026

This might not look like much, but it's 149KB of uncompressed VGM data streaming from disk on a BBC Micro with a total of 32KB of memory. Next I'll add the inflate decompression to the streaming and hopefully playback to the SN76489. 🤞

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Negative Charge @negativecharge.bsky.social · 26/04/2026

Something I've wanted to do for a while is create a generic .VGM / .VGZ player for the BBC Micro. Here's stage 1... deflate the .vgz file in memory, read the VGM header and GD3, setup interrupt based on playback speed and send to the SN76489. Next step is to look into streaming playback and SWRAM.

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Negative Charge @negativecharge.bsky.social · 07/04/2026

My universal converter for the BBC Micro SN76489 now contains support for over 15 PSGs and 20+ different input file formats. Most of the converters have been rewritten from scratch. Here's the latest addition... the .sndh converter that shares code with the .ym and .ay converters now. 🔊

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Negative Charge @negativecharge.bsky.social · 27/03/2026

I've been working on a universal music converter, and revisiting some older tools to include. Here's a much improved SAA1099 to SN76489 converter that I'm integrating (Any glitches are my rudimentary player). All my converters use an intermediate format before I compress to 3 tone/1 noise channel.

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Negative Charge @negativecharge.bsky.social · 08/03/2026

As converting NES .nsf files is very similar to converting .hes files, it didn't take much to add this to the converter. As a bonus I added VRC6 support too so I could convert some of the tracks from Castlevania 3 - Dracula's Curse JP. Need to find a good source of new modern .nsf files now. 🔊

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Negative Charge @negativecharge.bsky.social · 07/03/2026

Continuing my PC Engine HuC6280 to BBC Micro SN76489 converter. I've added support for .HES / .m3u files as input which expands the available content for conversion. It also tries to intelligently compress the channels down to three tone and one noise. Not too bad so far. 🔊

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Negative Charge @negativecharge.bsky.social · 28/02/2026

I've been working on a new HuC6280 (PC Engine/TurboGrafx-16) to BBC Micro SN76489 converter. Quite a challenge to fit 6 channels into 3, but trying a new technique with arpeggiation. 🔊

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Negative Charge @negativecharge.bsky.social · 23/01/2026

Trying out some visualisation effects in the player, making better use of the space and moving the track metadata into the scroll text. Broken a few things along the way, but so far working okay even with the software bass active. Now to reduce the number of cycles it takes to display. 🔊

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Reposted by Negative Charge

いぬふと @inufuto.bsky.social · 20/01/2026

Acorn Electron版 AWASS #acornelectron inufuto.web.fc2.com/8bit/awass/#...

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Negative Charge @negativecharge.bsky.social · 18/01/2026

I thought I'd give the Acorn Electron port of the Squeeker Plus 1-bit engine a go, not expecting much considering the demands on the faster BBC Micro. However, venturing into the murky realms of illegal NMOS 6502 op codes, it's playing!.... badly, but it's at least recognisable with its issues.

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Negative Charge @negativecharge.bsky.social · 10/01/2026

Very much a work in progress, but quite a while ago @h0ffman.bsky.social shared his .1tm file for 1-Bit High and Rising. The intention was to port the Z80 Squeeker Plus engine to the 6502, but it proved to be difficult... until now. Pitch is wrong.... but it's finally playing . More work to do! 😊

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Negative Charge @negativecharge.bsky.social · 04/01/2026

Today's demo effect on the BBC Micro... the iconic spinning cube. Here's a very basic version with backface culling. I wasted 10kb on double buffering, so there's only room for a short sound loop on this one. There are much better spinning cube examples already on the Beeb. 🔊

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Negative Charge @negativecharge.bsky.social · 02/01/2026

Today we have a classic scroller on the BBC Micro with a slight twist... custom font scaled dynamically to 16x16 pixels and continuous gradient applied to give the impression of more colours than supported by Mode 5. All software scrolling (no CRTC abuse) so works on the Acorn Electron too. 🔊

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Negative Charge @negativecharge.bsky.social · 01/01/2026

Another attempt at a BBC Micro Mode 7 demo effect today - the Moiré pattern. Could do with some colour and further optimization, but just wanted to get the basic effect working. This demo is accompanied by some classic Mad Max {Jochen Hippel) music. 🔊 #bbcmicro #demoscene

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Negative Charge @negativecharge.bsky.social · 31/12/2025

More 6845 CRTC experimentation on the BBC Micro. This time it's Mode 1 and an infinite vertical scroller. I'm probably not doing this right as it's not as smooth as I would expect. Need to do some more reading on this one. No music with this demo. #bbcmicro #demoscene

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Negative Charge @negativecharge.bsky.social · 30/12/2025

Experimenting with the BBC Micro's 6845 CRTC to do some smooth full screen hardware scrolling. Not something I've attempted before and I can see a number of possibilities. This is a simple Mode 5 dynamically generated gradient that I'd have a lot of difficulty moving at this speed in software. 🔊

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Negative Charge @negativecharge.bsky.social · 29/12/2025

Today's demo effect on the BBC Micro... water ripples. This would be much better in higher resolution so I may try a Mode 1 or 5 version. It doesn't quite follow the original algorithm due to the resolution constraints. 🔊 #bbcmicro #demoscene

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Negative Charge @negativecharge.bsky.social · 27/12/2025

Another demo effect on the BBC Micro with music... it was going to be a dot tunnel demo but I haven't yet got the tunnel effect working, so here's a variant. 🔊 #bbcmicro #demoscene

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Negative Charge @negativecharge.bsky.social · 20/12/2025

Today's BBC Micro demo effect.... it was going to be a rotozoom, but I can't get the rotation looking right or at a reasonable speed at the moment, so here's a panning, zooming checkerboard with music. 🔊

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Negative Charge @negativecharge.bsky.social · 17/12/2025

Experimenting with trying to recreate some classic demo effects on the BBC Micro, starting with plasma. The version I have in Mode 5 looks better, but was slide show speed so moved to Mode 7. Needs more optimization, and the plasma effect can be improved. Added some music too. 🔊

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