Over the Easter holiday, I was fiddling around with my first computer: Spectravideo SV-318.
It’s funny how I sometimes insist it was “SVI-318”, but apparently the box and the machine itself says SV-318. I was a weird kid. Probably the confusing part was that a lot of peripherals used “SVI” as short for “Spectravideo” and SVI supposedly stood for International models. I don’t know. It’s been ages.
The machine itself works just fine. It boots up with a quite a colourful display of its logo…
…after which it gave me some grim spectres of things to come. Specifically, the name of the company most people would be blaming a lot of things on.
(Well, Microsoft has done a few good things. Microsoft Extended BASIC, as displayed here. Xbox in general. I suppose Windows 7 is passable. Eh…)
This experiment is about a game that I happen to have. Unfortunately, as I got the computer from a relative of mine when I was a kid, I got this game with its cover card missing. So apparently, at some point, I made my own card, even when I had no fucking clue about English language. Or what satellites looked like. Or how to draw shit.
Now, kids out there may be wondering what the hell kind of game media is this. This is a cassette tape.
So a short history lesson for total newbies: Cassette tapes were cheap and ubiquitous, and in one dreadful point of history, they were used for storing music. Sound quality was decent (but MP3s are zillions of lightyears ahead), you could only fast-forward and rewind the tape (no track/song selection), and of course it’s cheap magnetic media so the sound quality could deteoriate or it could get erased due to magnetic fields.
And, of course, they could be used to store computer data by converting a digital bitstream into analog audio signal, and vice versa. Kind of like modems. (…wait, kids don’t know about modems either. sigh ask your grandmother.) While the storage medium is cheap, it’s a very slow method of storing data. Error-prone, too.
So what have we got above? A strange Spectravideo game title called Space Satellite.
You may notice one thing: The tape itself looks a bit weird. Most commercial bits of software had professionally made tape labels. Spectravideo software had pretty much uniform tape labeling, since most of the software was published by Spectravideo themselves.
This one is from Spectravideo Software Library, which was… probably something that is sort of affiliated with the official Spectravideo functions, or something. Or some kind of a software club thing. I don’t know. It’s apparently not part of the “normal” Spectravideo line.
Here’s another guy’s photo of the tape cover. Note, however, that this is the MSX version, for the later models of Spectravideo computers (and all MSX compatibles, I guess). The game itself was written in BASIC language, and the Spectravideo BASIC and the MSX BASIC were pretty similar, so the games would have been reasonably same.
What’s also quite interesting is that the labels aren’t the same. I originally suspected that the tape I have is a pirate version, but it seems that the cassette itself is identical to this one, just that the label is less featureful. It’s also printed on the cassette itself, which means it’s been industrially produced or something - pirates wouldn’t have gone this far. Also, the cassette only has about 4 minutes of tape, which is indicative of commercial production, though it also doesn’t have starters or enders (sturdy non-magnetic pieces of tape at the ends of the tape, meant to make the rewinding more reliable so that the tape won’t snap at the end).
The photograph link above also has a few tidbits. Apparently the game was distributed as a free extra to buyers of Spectravideo SVI-728 MSX computer. The link also has something I never had: the actual instructions to the game. The description from the photographer and transcriber says “the instructions are probably longer than the actual game program itself”. Yup. The game was bloody impossible to comprehend without instructions.
However, when I tried to play the game…
…I was hit by something I didn’t really want to see.
“Device I/O Error” means “I have this one method that says whether or not I could actually read the game from the tape, see, and it says there was an error”.
Now, here’s the problem: I managed to get this error before. It’s probably got something to do with the tape drive rather than the actual game. I just can’t remember what I did to fix the thing. Or whether the error was actually recoverable to any capacity.
So instead, I’m going to do something else. Some preservation efforts that are unfortunately in mid-way.
I did this.
Hooked up a cassette player on my computer, fired up Audacity, and just recorded the bastard to a .wav file.
The problem is that the game is stored on an unreliable medium in an analog signal format. So what I need to do is to treat the thing as a pile of sound. It can be subjected to all sorts of modern-time sound processing tools. And then just play it back to the tape.
Live and learn, kids: You need to press record and play buttons at the same time to record.
And since the computer processing power has increased considerably since mid-1980s, we can even perform fantastic feats my kid brains couldn’t even imagine at the time.
I can essentially decode the sound using software, essentially replicating the tape drive as an application.
I’m also a Commodore head, and I know a whole school of copy protection techniques for Commodore 64 games was based around the notion that the games were recorded at fainter signal level, which made copies made using home double-tape decks not work. But now I can pit these copy protection mechanisms against modern advanced technology and formerly professional-only-grade audio repairing software that is nowadays available for free.
Unfortunately, I didn’t have enough time to actually experiment a whole lot in the holidays, and I had some very limited access to tape recorders. But I’ll do my best in the future. Another problem is that I have absolutely no idea about how to decode Spectravideo tapes on software - if the modulation/demodulation system was somehow described somewhere, that would be fantastic. I’m not exactly a DSP geek, but decoding these signals would be an interesting challenge!