JSSpeccy: A ZX Spectrum emulator in Javascript

October 19th, 2008

I’m really typecasting myself here. If there were an international “Person most likely to write a Spectrum emulator in Javascript” award, I’d have taken it for the last five years running. So here it is – probably the most stereotypical project I’ll ever come up with.

Writing this wasn’t actually such a big deal – the Z80 core was ported from the one in Fuse, with the Perl-and-C-preprocessor-munging trickery still intact, and Javascript is syntactically close enough to C that that wasn’t a mammoth task. (I got 90% of it done on the train journey back from International Vodka Party alongside recording silly songs about tube stations.) The one fiddly bit was working around the places where the Fuse code used low-level C constructs to its advantage: using unions to chop and change between individual registers and 16-bit register pairs, and relying on limited-size C data types (often in pretty subtle ways) to truncate 8-bit and 16-bit values at the right time, whereas Javascript only has integers. (Actually, the really time-consuming bit was debugging it all… luckily, Fuse has a rather excellent test suite too.)

The rest is just creative abuse of the <canvas> element, as usual… it’ll take advantage of the putImageData interface to do the pixel pushing if available (on my machine Firefox has it, Safari doesn’t) and fall back on drawing 1×1 pixel rectangles otherwise. This time I’ve thrown in Google’s ExplorerCanvas as a nod to those poor unfortunates still stuck with Internet Explorer. Incidentally, I’d be curious to know how it rates on Google Chrome (I don’t have an XP/Vista box to test on) – if the hype is true (and it implements the putImageData interface like all good up-to-date browsers should) then I’d expect it to comfortably reach 100% Spectrum speed on modest hardware.

Belorussian translation of this post provided by movavi

Posted in Hacks, JSSpeccy, Javascript, Spectrum | 94 Comments »

The Model (unplugged cover version)

October 10th, 2008

Another month, another musical challenge bandwagon to jump on. For October the FAWM / 50/90 crowd is turning its attention to cover versions. So here’s a not-very-Kraftwerk-like instrumental version of Kraftwerk’s The Model.
Download matt_westcott_-_the_model.mp3

Download The Model (MP3, 4.7Mb)

Posted in FAWM, Music | 4 Comments »

Antisocial

October 9th, 2008

This is it then… my big comeback to the Javascript demo scene after a two year absence, and also the moment when my demo coding muse returned from a long holiday, I guess. Ladies and gentlemen, I give you… Antisocial, a biting satire on social networking phenomena.

Visit the Antisocial microsite…

With my characteristic lack of organisation, I found myself with two weeks to go to the Sundown party, having promised a demo release, and with nothing specific in the pipeline. So, I decided to take a chance and run with an idea that had been sitting on top of my “demos to write when I have more free time than I do right now” pile for the best part of a year. I had it all planned out in my head, right down to the soundtrack: a mysterious track from an unlabelled CD I picked up at a ZX Spectrum Orchestra gig in 2005 (which turned out to be Round, from their Clive Live^3 EP). A quick bit of permission-getting later, and I was at the point of no return.

I knew it would be an ambitious job, and a bit of a leap artistically and technically from my usual stuff. I pencilled in a rough project plan in my diary. I drew up storyboards. I read up on the maths that was too nasty to contemplate on previous projects. And shockingly enough, I actually enjoyed all of the above.

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Posted in Canvastastic, Demoscene, Hacks, Javascript, Talks | 8 Comments »

50/90 2008: somewhat fewer than 50 songs

October 6th, 2008

50/90, or 50 Songs In 90 Days, is the less photogenic and slightly more intimidating cousin of February Album Writing Month, running throughout July, August and September. The idea is to write fif- oh, you worked that bit out already. This year FAWM supremo Burr Settles donated the song-posting infrastructure to 50/90 (previous years were run through a Yahoo group) so it became a natural off-season hangout for FAWM veterans. Me, I wasn’t planning on taking part, but since I ended up writing a couple of songs over that time period for one reason or another, it would have been silly not to crash the party late on and participate in a laid-back, not-letting-it-take-over-your-life sort of way. And here are the results.

Everything Is Relative


Download matt_westcott_-_everything_is_relative.mp3
This started out as an instrumental track laid down at Shucon 2008 on TDM’s GarageBand / MIDI setup, which came back to bite me as a nasty bit of vendor lock-in. (I figured that since GarageBand took MIDI input and stored it as MIDI-like note events, I’d be able to export it to a .mid file, right? Silly me.) Luckily I managed to salvage / re-record enough of it to work on it some more and develop it into a proper song. Spurred on by some particularly eclectic music competitions at Assembly, I decided to try my luck at entering it at Evoke, just to see what would happen when it was thrown in against a whole load of D+B and trance tracks. Not surprisingly, it failed to qualify. But having done the rounds of more or less the entire summer demo party season, it found a home at Sundown 2008, where it got 4th place. Score!

The lyrics were actually sparked by the train journey back from Shucon – at the seat in front of me, I saw that someone had drawn some initials in a heart on the window. This made me think “eww, that’s a bit tacky. Oh, hang on – whoever did that drew it on the outside of the window but did it in mirror writing so his girlfriend on the train could read it. Aww, that’s like the most romantic thing ever!”

Edgware Road


Download matt_westcott_-_edgware_road.mp3
A slightly more obviously train-related song, written to immortalise that enigma of the London Underground where time stands still, and add to the repertoire of songs about tube stations. Lyrics were mostly written on the Eurostar (hence the namecheck in the bridge) and the recording was done a-cappella stylee in the cabin of a sleeper train on the way back from International Vodka Party. Naturally, this was a horrible painstaking process of waiting for the moments when the train wasn’t making an absolute racket, but it had to be done for posterity. How many other songs have been written and recorded entirely on public transport, eh?

Cabbage Soup For The Soul


Download matt_westcott_-_cabbage_soup_for_the_soul.mp3
Written for Hoopshank as part of intense negotiations (not really) over contributing to another as yet unannounced musical project. He demanded songs of cabbage… I answered the call. I added a self-imposed constraint that the song had to have a mostly-serious message, so I came up with the idea of cabbage soup for the soul, as being something like Chicken Soup for the Soul but not as pleasant, and better for you. And suitable for vegans. And with that, the song just wrote itself. Or, more accurately, was written on my behalf by my alter ego, fictional Scottish indie band Glencoe Horse.

At The River (slight return)


Download matt_westcott_-_at_the_river_slight_return.mp3
OK, scraping the barrel a bit here. But you can’t really blame me for having a sudden bout of obsessive-compulsive disorder on realising that the lyrics to At The River by Groove Armada consist entirely of a half-sentence that trails off unsettlingly without completing its train of thought. “If you’re fond of sand dunes and salty air, quaint little villages here and there,” – then… what exactly? Clearly, this had to be fixed. So I did.

(All songs downloadable from the not-very-pretty music.matt.west.co.tt – lyrics available from my 50/90 profile)

Posted in Demoscene, FAWM, Music | 4 Comments »

The Ninja Milkman Conspiracy (and Maze)

October 5th, 2008

I’m a bit behind in my blogging, so I’ve got a bit of a “what I did this summer” catchup to do. First up is The Ninja Milkman Conspiracy, a cheap and cheerful oldskool scrolly Speccy demo made for this August’s International Vodka Party, featuring the classic circle interference effect, some creative use of dithering, and a dancing robot. What more could you ask for? The title, incidentally, was just something random and irrelevant to save it from being called ‘IVP 2008 demo’ (which is just as well, because there were already 2 other demos in the competition called that) but is actually a reference to the milkman at one of our offices who is able to deliver the milk and disappear without making a sound.

…All of which is ordinary enough, but the exciting thing (if you’re the sort of person to get excited about build scripts) is, um, the build script. I’ve been happily using makefiles for ages, but this time I finally flipped at the amount of redundant boilerplate you need to shove in there for a typical Spectrum project, even a small one like this – having to remember command line syntax, having to explicitly set up dependencies even though they’re all clearly marked as ‘include’ lines in the assembler file – so I came up with Maze, a Spectrum-oriented replacement for Make written in Ruby. Inevitably, being a scratch-my-own-itch sort of program, it’s a bit more hard-coded (and tuned towards my own way of working) than I’d like, but I reckon it’s enough of an improvement over bog-standard makefiles that it could conceivably be useful to other people. And if it is, maybe I’ll be encouraged to rewrite it in a more open-ended way some time…

Posted in Demoscene, Ruby, Spectrum | No Comments »

Some rather opinionated plugins

August 30th, 2008

Update: The belongs_to patch has now made it into core Rails. Thanks to Jon for persevering with it where I threw in the towel, and to Koz and Pratik for giving it their attention. I’m still not entirely convinced that going through the conventional channels (as opposed to “whinging on a blog”) would have yielded the crucial feedback to get the patch in a state where it could be accepted, but all’s well that ends well…

A shark, being jumped, yesterday.Take this as the rantings of a pissed-off curmudgeon who’s had his second core patch rejected if you will, but it’s my sad duty to report that Rails has jumped the shark. It happened when it stopped being a framework and started being a collection of opinions instead.

You see, in my book a framework is something that’s meant to make programmers work more effectively – not to lecture them about what they’re doing wrong. Lecturing can be a good thing, as long as it ultimately results in better code – I’ll happily admit that following the Rails learning curve has taught me an awful lot about good programming practices. More and more though, I’m finding it being used to justify just plain broken features: If it doesn’t work, it’s your fault for not doing it the right way. Take this bit of profoundly broken behaviour:

let’s say we have a Company model, which belongs_to :city

>> torchbox = Company.find_by_name('Torchbox')
=> #<Company id: 1, name: "Torchbox", city_id: 1>
>> torchbox.city
=> #<City id: 1, name: "London">

Aha, we’ve got the city wrong. Let’s reassign a bundle of attributes then, like we would if we were doing this through a web form:

>> torchbox.attributes = {:name => 'Torchbox', :city_id => 2}
=> {:name => 'Torchbox', :city_id => 2}

Right, so now we should retrieve the correct one.

>> torchbox.city
=> #<City id: 1, name: "London">

Er, oops.
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Posted in Hacks, Rants, Ruby | 19 Comments »

Spacecake

August 3rd, 2008

When I’m writing Speccy music, I’m always very conscious of stereotyping myself. At the Forever party, they gave up on anonymising music competition entries after realising that everyone in the room recognised the Gasman entry (and the Yerzmyey entry, the Factor6 entry…) within two seconds of it starting up – even if I’d gone to great lengths to reinvent myself.

This time, with two or three days left before Assembly and nothing to show, I decided to make it easy on myself, and stick with what I know – the primal boop-durr-tish-durr bassline, the crowd-pleasing echoing cascades – and not be too bothered about basking in my signature style. As a result, it’s not the most original piece of music I’ve ever written, but it did its job – it made first place in the Extreme Music competition where it was up against PC soft-synths in addition to the now familiar Commodores and Nintendos.

The title isn’t a bid to stir up controversy with drug references, by the way. I just liked the combination of words.

Download gasman_-_spacecake.mp3

Posted in Demoscene, Music, Spectrum | 2 Comments »

Comet Chaos

July 7th, 2008

Thanks to Oleg for reminding me at OpenTech that I still hadn’t written this up yet…

This started out as an experiment in Comet techniques (which allow you to actively push data out from web servers without the client having to initiate the request) which quickly ballooned in ambitiousness – I didn’t set out to write Just Another Chat Application after all. The end result is a realtime multiplayer Javascript conversion of the Spectrum wargame Chaos… or a reasonable chunk of it, at least.

Play Comet Chaos now

If you’re interested in the workings behind it, check out this video from my Oxford Geek Nights presentation to hear about how Comet is like a small child on a car journey, find out how close web developers can get to world domination, and watch a live demonstration going pear-shaped.

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Posted in Hacks, Javascript, Ruby, Spectrum, Talks | 1 Comment »

Wi-fi is GRATE.

June 6th, 2008

Sitting in my garden this evening when an impressively-coloured bird landed three or four feet away. It just so happened that I had a portable device with me which could tell me, without me having to make any sudden movements or noises that would scare it away, that it was a goldfinch.

Now tell me. When, in the entire history of civilisation, has that been possible before now? Technology – it’s blimmin marvellous.

Posted in Uncategorized | 4 Comments »

AY Club: Breath Of Air

May 10th, 2008

As a postscript to the release of tracker2ay, here’s the reason I wanted to transfer tracker files back to the Spectrum in the first place: to play X-Agon’s 6-channel Breath Of Air (as featured on the AY Riders Satellite single) the way that God intended, on two Spectrums playing 3 channels each…

Posted in Demoscene, Music, Spectrum | 4 Comments »

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