I think it was the ZX81 (and later the Spectrum) where my brother and I had it hooked up to the mains on my parent's boat. The problem was there was only one 12V battery (via a voltage regulator) which not only powered lights and our computer, but also served the engine. If we were sailing and the wind dropped, we established a protocol where my Dad would have to give sufficient notice for us to save whatever we were working on to tape before he started the engine, as the starter motor drew enough current to dip the voltage below the 9V the ZX81 needed, thus causing it to crash. And of course, RAM wobble wasn't helped if there were heavy waves. It's amazing what we put up with just to get some computing time.
The ZX81 Turns 40
41–50 of 84 posts
Re: The ZX81 Turns 40
#42The first computer I saw [0], and the first computer at home [1], were Brazilian clones of the Sinclair ZX81.
That's where I learned to program, in Basic. It changed my life.
Thanks Sinclair.
0 https://en.wikipedia.org/wiki/TK82C 1 https://pt.wikipedia.org/wiki/CP200
Re: The ZX81 Turns 40
#43I just posted a pic of my highly modified ZX81 here https://mobile.twitter.com/njcw/status/1368566103933337603 In honour of the #zx81 40th bday I got mine out the attic. I modified it heavily to have external keyboard, programmable character generator and easy access to swap the ROM. I killed it trying to upgrade to 48k RAM but I haven't the heart to dispose of my first computing love! In those days I obviously had n…
What is the keyboard in your photo? The lack of oversized keys has me confused.
Also, love that it is a 3,284,741 byte image of a ZX81. And the ,/< because -- presumably -- a dog ate your 1 ;)
Re: The ZX81 Turns 40
#44In terms of ROI, the best £69.95 I ever spent (I still have the receipt from WH Smith). It wasn’t the first computer I ever used, but it’s the first one I ever owned at age 9 and it led me down the path that’ll be familiar to many here... I’m glad I still have it, and the Spectrum and Amiga’s that followed. Incredibly, the ZX81 hardware and software scene is still alive. You can get parts for it quite easily, includi…
ZX81 -> ZX Spectrum -> Atari 520ST
It wasn't the first computer I used but it was the first computer I owned. I still have all the hardware somewhere (including minutia like the ZX Microdrive sitting on my desk right now), I have some books as well ;)
Re: The ZX81 Turns 40
#45If like me you have fond memories of the ZX81 (though not perhaps of the keyboard), then you might find this print interesting: http://www.alisoneldred.com/john-harris/fine-art-prints-1/sc...
Good find. For me the artwork looks better as the manual with the red writing.
Re: The ZX81 Turns 40
#46I had one of these at age 10. I still have it (at age 50) and it still works. Also the printer and a roll of paper. Whenever people ask me what my earliest memory is, I say the 16k RAM Pack. :)
My inner nine year old envies you for having the printer and paper.
I will memorise your earliest memory joke.
Re: The ZX81 Turns 40
#47I grew up on the Apple ][ but I can certainly relate to some of the stories here. Except now I hate Apple for turning into such a snob company :(
Imagine a Sinclair laptop. With options for a monochrome screen and a flat membrane keyboard. There would be no internal battery, just a wedge shaped power brick. The case would be black. RRP? 99.99
Re: The ZX81 Turns 40
#48I had one of these at age 10. I still have it (at age 50) and it still works. Also the printer and a roll of paper. Whenever people ask me what my earliest memory is, I say the 16k RAM Pack. :)
I'm 40, I vaguely remember my parents had one at some stage, and I'm reasonably sure it had the 16k RAM pack, but the first I really remember is the ZX Spectrum with the 48K ram, and rubber keys. First thing I ever programmed, though mostly I wanted to play Chucky Egg, Manic Miner, Granny's Garden etc.
Re: The ZX81 Turns 40
#49I just posted a pic of my highly modified ZX81 here https://mobile.twitter.com/njcw/status/1368566103933337603 In honour of the #zx81 40th bday I got mine out the attic. I modified it heavily to have external keyboard, programmable character generator and easy access to swap the ROM. I killed it trying to upgrade to 48k RAM but I haven't the heart to dispose of my first computing love! In those days I obviously had n…
What is the keyboard in your photo? The lack of oversized keys has me confused. Also, love that it is a 3,284,741 byte image of a ZX81. And the ,/< because -- presumably -- a dog ate your 1 ;)
It is a cast off relay keyboard - easy to wire up to the ZX81. I don't recall where it came from, but I don't think it ever had a 1 key as was common on typewriters back then (you just used l instead).
Re: The ZX81 Turns 40
#50Earlier quoted context omitted.
I just tried it on the ZX81 online emulator: http://www.zx81stuff.org.uk/zx81/jtyone.html You have to type the following sequence of keys: P [Shift]I 2 [Shift]H 3 2 [Shift]O - [Shift]I [Shift]I 2 [Shift]H 3 2 [Shift]O - 1 [Shift]O Enter which should appear as: PRINT (2**32)-((2**32)-1) It prints 0 which is not the expected answer! (The 0/0 at the bottom of the screeen is an OK message, the answer is printed in the to…
0 is actually what I'd expect as an answer. Even on very modern Python you get In [1]: 2.0**64 - (2.0**64-1.0) Out[1]: 0.0 Thats how floats behave like with operands that differ greatly in magnitude. Also this In [2]: 2.0**64 == (2.0**64 - 1.0) Out[2]: True
"1" in Scheme:
>(- (expt 2 64) (- (expt 2 64) 1))
1