Archive for the ‘Random Stuff’ Category

YouTube activity

Monday, May 26th, 2014

So things have been a little quiet of late, but people following me on social media (I think there are four… it would be more but my mum isn’t interested in the internet for some reason!) will have seen a couple of videos with test code so I might as well post here to talk about them a little more because it’s a bank holiday Monday and what else is there to do apart from watch Bond films?

The first video from a few weeks ago stars a Mockingboard sound driver. The Mockingboard series of cards seem to be the most common sound expansion for the Apple II series so when I was in a demo coding mood a few months back, it seemed a good idea to write something to play tunes with it rather than using the beeper. The tune itself is the loader from the excellent Atari ST demo Ooh Crikey Wot A Scorcher by the Lost Boys, composed by Jochen “Mad Max” Hippel.

Essentially, the driver is playing back a .YM sound file (the idea came from the legendary Matt Simmonds’ recent work at playing these files on the C64) which has been unarchived and unceremoniously ripped apart into individual streams by a cheap and cheerless converter before being RLE compressed to make it marginally more efficient. I’ll be the very first to raise my hands and admit that it’s a hideously messy and memory-consuming approach, but it was a first attempt and the next step will be to write an actual music driver for the Apple II game I started ages ago. The three reasonably complete demo parts already using this driver should hopefully be tidied up and linked for release fairly soon.

Secondly, there’s the footage above of a 24 character line scroller on the Commodore PET. Everybody knows how it happens; you wake up one morning and just get that urge to write a hardware scroller for a 1970s home computer that updates at one character per frame… erm, right? Oh, just me then.

This was something I was messing around with ages ago but tidied up and modified to move actual tile compressed landscapes past. The start of screen RAM is being incremented once per frame so the only real CPU usage comes from adding new column of data is added to the right hand side in a similar way to my Callisto scroller for the Atari 8-bit but, surprisingly, a bit more memory efficient. I’ve no real plans for anything to do with this code at the moment, but a “dodge the landscape” style game might be an option at some point…

Another day off… with MP3

Thursday, August 1st, 2013

Today’s new toy is an MP3 player shaped like an audio cassette that can be popped into an old car stereo to play music… except it’s being loaded with MP3s of games and fed to an Amstrad CPC464:

The results are surprisingly good considering the thing cost under a tenner including shipping! Amstrad CDT files are converted with TZX2WAV and then MP3 encoded with Audacity before they’re dumped onto the player’s SD card. The only problem I’ve found so far is that if there are a lot of files on the “cassette” it becomes difficult to locate the correct one; my plan to get around this is to add speech before each file which says what it is so that I can plug in headphones and skip through to the right program.

The two questions I have to answer next are if this machine will play nicely with an GBS-8220 VGA upscaler and where did I leave the MP1 modulator because it’ll make a great PSU for taking the CPC464 to events!

The game being loaded and played is Relentless by Paul Kooistra, the winner of the recent Amstrad CPC 16K competition over at CPC Wiki.

A day off… with VGA

Thursday, July 25th, 2013

Today I’m having a “day off” so, because this is what I assume everybody does when they have a little free time, it was spent fixing my Amiga 600HD after an “incident” where it’s previous CF card reader was damaged (a long story involving a CD32, an SX-1 and a dodgy HDD cable), failing to breathe some life back into a Cumana external Amiga floppy drive and playing with a few bits purchased for my Raspberry Pi. The result of the latter is this…

…which is Chameleon Pi running off my old 256Mb model B Pi, a Playstation 2 DualShock pad connected through a USB converter and VGA out. Although I wasn’t entirely happy with the Atari 8-bit or C64 emulation, the Apple 2 seems reasonable and the plan was, amongst other things, to have something compact and friendly to use at events for games on hardware I don’t own. It also has a new case which cost about six quid, but no audio at the moment but that’s being worked on.

And for an encore, half an hour was then used to persuade the GBS-8220 VGA upscaler I purchased a few months ago that working with the Spectrum +2 would be a fun thing to do; this process mostly revolved around poking wires from the upscaler into the Spectrum’s video port.

At some point I’ll get around to actually soldering a plug onto those wires, although considering my lack of ability with a soldering iron that might take a bit of practise and building up to. The actual video output from the GBS-8220 is pretty decent, I noticed that there’s some smearing but it doesn’t look to be any more pronounced than what was coming out of the SCART cable and television used previously.