Sinclair ZX80 / ZX81 / Z88 Forums

Hi,

I'm a vintage computer collector/enthusiast from New Zealand. I have a ZX81 and have recently uploaded a YouTube video showing my take on it. Members might be interested, so I'm posting the URL here: http://youtu.be/7KsuTg1qHIE

Terry (tezza)

Welcome aboard! Nice video!

Greetings from Spain.

Happy New Year!

Welcome, tezza. Nice video of the Zeddy.

Welcome Terry!

I'm glad that you changed your mind about the Zeddy. Back in the day I too did not think much of the ZX81. I discovered computers while at secondary school. The shops had ZX81's, the just launched ZX Spectrum plus Commodore VIC-20 and 64 (and some other makes). Who would want that little black box with the membrane "keypad".

My first computer, was a ZX Spectrum, but I wished for a machine with a nice proper keyboard, like the Acorn BBC Micro (which was the main computer used at school). Of course, lots more money was needed for these more expensive computers.

But also having an interest in electronics and how things work, it is amazing and fascinating what Sinclair did to put together the ZX81, a real computer (it has a real Z80 CPU, real memory, a real TV display system). But done in the most cost effective way, so keeping the price low. Which was his main objective. This took so much more engineering skill than most people imagine!

And just look at what people have done with it, the software (amazing what people have done in 1k) and the various hardware devices that were developed.

In the early history (1980 to 1986) of home computing many machines have come and gone, nearly all of which had better, well everything hardware wise, but how many are remembered now. Just a handful.

Mark

Yes, a good measure of the "classic" nature of a computer is "impact" and the ZX81 certainly had that.

It's a lot of fun making these videos and allows me to both "rediscover" and gain a deeper knowledge of these units in my collection.

BTW, has anyone else noticed that modern TVs have trouble tuning to the ZX81?

Terry (Tez)

tezza wrote: BTW, has anyone else noticed that modern TVs have trouble tuning to the ZX81?

Could be because the RF modulated signal is not really a PAL signal. I think the tuner could claim a missing burst pulse used for color synchronization. Very old black/white movies could be near that wave form but today the signal is digitally worked up, added maybe the color burst. The second think is wrong sync pulses. Normal TV signal is coded in frames and even and odd frames are coded different with a series of small sync pulses. The ZX81 doesn't provide this information. So could be a so called loss-of-sync-detector circuit which tries to find a valid TV sync signal including frame coding and if it doesn't find it could be processed as no or bad signal on the channel.

Just an idea. My SONY plasma TV does accept the signal over channel 36 but this was configured manually by me. And it's constructed in 2004.

tezza wrote: BTW, has anyone else noticed that modern TVs have trouble tuning to the ZX81?

Welcome to the forums - could I ask you to add a link on your page about the ZX81 please ?

Modern TVs do have problems with the ZX81 display - that is one of the reasons why the ZXVid was born

RWAP wrote:Welcome to the forums - could I ask you to add a link on your page about the ZX81 please ?

Done!

Good to know the TV issue is a universal problem and just not me!

Terry (Tez)

Very nice vid there, tezza!

Especially like the background you give on things like how it was marketed, Sir Clive, other machines around at the time, RAM pack wobble, working with old TV's / taperecorders etc. That's exactly the kind of thing eg. Wikipedia is often a bit short on. I lived through that period myself (and used a ZX81 back then!) so I know what it was like, but it's hard to convey the feeling of those times to today's iPad generation...

Hi.
Cool one. I'll look closer when I get home.
Byez,
Y