Turbo loading ZX Spectrum games via iPhone.

Way back last year, I witnessed one of my friends from the Retro Computer Museum loading a  game on to a vintage Sinclair ZX80 that was connected to his iPhone. Not only did this totally knock my socks off,  amazingly the game took literally 10 seconds to load instead of the usual five minutes like in the old days of painstakenly loading from tape. <groan…remember multiloads!>.

I’ve had my iPhone for a few months now and this is something I’ve been wanted to try so last week I got everything setup and had a go. Unfortunately after a few hours I was getting nowhere and  the closest thing I got to loading a game was displaying the loading screen from Arkanoid on my Spectrum +3.

So close but it always crashed at the last second 😦 DOH would have to wait.

After getting a few more tips from my friend yesterday I thought I’d give it another go. At first, I was still getting nowhere again so was quite the surprise when one actually loaded!

Here’s how I did it.

I downloaded and installed OTLAplayer on my Netbook (Windows7). This program is used convert images of Spectrum games into high speed .wav or .mp3 sound files that can be played back on your iPhone or MP3 player instead of audio tape.

http://code.google.com/p/otla/downloads/list

I then downloaded a few tape images (.tzx) from the World of Spectrum.

http://www.worldofspectrum.org

I loaded OTLAplayer, and converted the .tzx file to a .wav file. I found the following settings would give me a high success rate (although i had to tweak them slightly if I wanted to use another audio device like my Mp3 player).

To transfer the .wav file to my iPhone, I use Dropbox. This is a wonderful cloud storage service that supports a whole host of devices. You get 2GB of online storage for free and can pay a small subscription charge if you want to increase this. For me, I just use it as temporary offsite storage therefore 2GB is plenty for me.

With the .wav file now accessible on my iPhone I connected one end of a standard 3.5mm phono cable to the iPhone headphone socket and the other end to the Tape input jack on ZX Spectrum +3. The same principle applies to my other Spectrums apart from the +2 model because this model had an intergrated deck deck therefore has no input jack. You could use one of these instead?

With everything connected, I went through the usual process as if loading a game from tape but played the sound file via my iPhone instead.

After a few seconds the game  loaded and the fun begins!

One of the key things I’ve learnt is to get the volume levels correct on my iPhone. At first I couldn’t figure out why the games weren’t loading until by chance I happened to play a music file on my iPhone by mistake whilst it was still connected to my Spectrum. Imagine my surprise as a very distorted ACDC track came blasting out of my TV speakers via my Spectrum. As I lowered the iPhone volume, the music track became less distorted and it’s the same principle for loading Spectrum audio files. Too much volume distorts the audio signal and, of course, lower volumes produce too weak a signal for the Spectrum to use. I found that the optimum volume on my iPhone was when it was set to number 11 (Just like Spinal Tap :-). Interestingly enough, the volume levels I had to set on my other MP3 player were completely different and so far, I’ve been unable to load any games via my iPad2.

Here’s a couple of videos I’ve created showing two games loading. The first is the quintessential ZX classic Manic Miner and the other, a pretty damn fine Phoenix conversion called Pheenix.

Apologies for the low video quality, the iPad camera is nowhere near as good as the one on the iPhone.