ZX81

header

Like many other geeks, I started out in the IT business when my old man bought me a ZX81 – in 1981 funnily enough. In fact it was a Christmas present and it arrived on the 21st December 1981. My mother bought me a black and white TV and I invested in a DKtronics keyboard. They keyboard had to be made and soldered in. Proper computing.

And like most geeks, I got it – and spent endless nights working away on little programs – probably when I should have been out drinking smoking and picking up women. Anyway, this was more interesting and I made up for that later.

I learned how to program and I learned how to use machine-code. 2 years later I had a choice of ZX Spectrum or Commodore 64. I chose the 64 and didn’t regret it. For some reason 6805 programming was far more enjoyable than Zilog stuff. I had that for a good while and eventually moved into IT as a chosen career as a programmer.

Times move on and while the ZX81 was a foundation of learning, it has limited uses today. However I wanted to have a bit of fun with it so I thought I would get it working again.  The net is awash with emulators of all kinds and most of the games have been converted to .p formats for use in emulators. Well I thought – whats the point of that ? I have a ZX81 here, I have the original B&W TV that my dear mother bought me so why cant I just so that – and for added geekness – can I use my iPOD Nano as a host for the games and just do a download from that ?

Well I did and this is how I did it:

Step 1 – Get a ZX81 with a 16K RAM pack. Get a telly and hook it it up. Switch it on and see the K cursor.  That bit is enough to have the memories flooding back.

Step 2 – Get a mono audio cable – http://www.maplin.co.uk/Module.aspx?ModuleNo=1170&doy=28m1&C=SEO&U=strat15 end to end male 3.5mm jack. Failing that, hack a stereo cable. I just wired it so that one end was mono. Then plug that into the PC headphone out on the sound card – you know the thing.

Step 3 – Get the software. Lots of sites, although a few are broken – The first bit you need is to be able to play .p files through the sound card – http://membres.lycos.fr/wintzx/ This french lad has done the biz and it works – although the interface is plesasingly French – i.e. not like anything else.

Step 4 – You need lots of .P files.  These are the original games converted for use in emulators.  This is where they are. I just downloaded the FTP archive. Have a look and get what you need.

http://www.zx81.nl/

Step 5 – Hang it all together. The secret I found is to do exactly what you had to do on the 81 – which was adjust the volume control just above where it starts to be recognised by the 81. I did this a few times using the 1k breakout.p program. Type in the command on the 81 – LOAD “BREAKOUT”. The screen changes. Then start the winTZX application. Load the .P file you want and then click on the bif green “play” arrow button. When the 81 recognises the incoming signal it changes to a black and white flicker. Adjust the volume so that it sees the signal but dont go much higher. Work with it until you see the classic white screen and 0/0 message at the bottom on the screen. Hit RUN and it should work.  I think I also used a FORTEST.P program because it was tiny and I was able to replay that until it came in.

Step 6 – iPOD. Easy. use WinTZX to convert to a WAV format. Then use the superb freeware, Audiograbber to make an mp3 – download it to your iPod and repeat steps above…. awesome. Using the iPOD as a ZX tape recorder.

Other Sites

Lots of good stuff out there – if you want to understand the signal and what its doing – say you have some have some tapes you want to upload and convert to .p format – have a look at this fellows excellent site. http://www.michaelminn.com/linux/mmzx81/index.html

Otherwise checkout http://www.zx81.de/webring/

A few pics of the escapade

zx01

My old TV – 25 years old and still going fine.

zx02

ZX with hack cable

zx03

ZX81 and expensive solid state tape recorder (iPOD)

zx04

Psion flight simulator was the only thing I every really played on the 81 – Still can and its still fun!  24 years on.

Advertisements

5 thoughts on “ZX81

  1. Yeah the Spectrum keyboard was better I thought. More like a PDA now…

    This lad will need to eaither get a bit of hardware – or… he could intercept the audio and decoded the binary from that and do it all on software.

    That’d be an interesting project

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s