Hello! New first time owner of zx81

Introduce yourself to your fellow forum members - what was your journey into the Sinclair world?
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AdrianPilko
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Hello! New first time owner of zx81

Post by AdrianPilko »

Hello sinclairzxworld,
As my topic says in the early 80's I was too young to own a zx81 being only 3 years old in 1981, but my older brother briefly had one before he upgraded to a Speccy. My first 8bit computer was a c64c in 1988 long since gone but it did start the seed for programming which is what I've eventually ended up making a living off (c, c++ on Linux mostly)

I love the whole 8bit scene and had been looking on ebay for a zx spectrum which I was lucky enough to win the auction. With an sd card reader it's a dream to load and run games. But then I somehow found wanting an earlier, the zx81 :D when I won an auction for an "untested" one on ebay I had to get it working which involved a composite mod, it has the early ula without backporch so needed the 555 timer one, and a new keyboard- the flex cables were broken. It works ok now and can load games through the ear jack but not been able to save any programmes so something might be wrong still on the board which i'll try and fix later.
I know you can run emulators like Eightone, and I do myself, but there's nothing quite like running on the real thing.
Anyway, all the best to you all,
Adrian
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mrtinb
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Re: Hello! New first time owner of zx81

Post by mrtinb »

The save signal that comes from the ZX81 is VERY WEAK. I don't know which equipment you are saving to, but some newer equipment might just ignore the signal.
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Lardo Boffin
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Re: Hello! New first time owner of zx81

Post by Lardo Boffin »

Welcome! Loading and saving on the ZX81 can be challenging. To say the least.

An old mono cassette player is generally the best thing to use.
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AdrianPilko
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Re: Hello! New first time owner of zx81

Post by AdrianPilko »

mrtinb wrote: Wed Sep 01, 2021 8:42 pm The save signal that comes from the ZX81 is VERY WEAK. I don't know which equipment you are saving to, but some newer equipment might just ignore the signal.
Hi,
yes have heard several people say this save signal is weak. I was trying initially to save to a wav file on a PC using just the standard windows10 sound recorder and mic input. Then i tried capturing it on my DSO but again couldn't discern between the noise and when it was saving. But just realised this was on the external jack not the board so the contacts in the 3.5mm barrel could be corroded (i have similar problem with the power connector being a bit sketchy).
Lardo Boffin
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Re: Hello! New first time owner of zx81

Post by Lardo Boffin »

The power socket often becomes dodgy as the part of the connector that pushes down on it becomes loose and no longer makes contact.

You can get new ones:

https://www.sellmyretro.com/offer/detai ... cket-37026

Its the same socket type for the mic and ear. In my experience though the mic socket gets far less use than the ear or power sockets so probably just needs a clean.
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ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Moggy
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Re: Hello! New first time owner of zx81

Post by Moggy »

mrtinb wrote: Wed Sep 01, 2021 8:42 pm The save signal that comes from the ZX81 is VERY WEAK. I don't know which equipment you are saving to, but some newer equipment might just ignore the signal.
Agreed the signal is very weak with a fair bit of noise in the background.

The ZX80 in comparison has a real kick to its output and only needs half volume from the loading device whereas the ZX81 is always flat out, thank God for SD card readers! :lol:
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1024MAK
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Re: Hello! New first time owner of zx81

Post by 1024MAK »

Hello and welcome to our forum Adrian!

:D :D :D

I hope you enjoy this forum :D

Keep in mind that the cassette output (mic) is designed to feed the mic input on a mono cassette recorder, which itself is designed for use with inexpensive microphones that produce low level signals.

Hence a ZX81/TS1000 (or any of the other versions around the world) has been designed to output a ‘weak’ signal. So you’ve got no chance with a line level input on a PC, laptop or other device. And it’s not much better even if the device has a actual half decent microphone input.

If you don’t mind modifying your ZX81, it is possible to change R29 and C11 and C12 to increase the output level.

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Neurogate
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Re: Hello! New first time owner of zx81

Post by Neurogate »

1024MAK wrote: Sat Oct 02, 2021 10:57 am If you don’t mind modifying your ZX81, it is possible to change R29 and C11 and C12 to increase the output level.
Another one solution - just remove R27 and C11. It's a very simple solution, but it works. Let me note, that in some versions of ZX81 board, R27 & C11 are not in its own place, but directly near to the mic socket.
Sinclair ZX81, Sinclair QL, Sinclair ZX Spectrum +2, Atari 130XE, Commodore 64C, Commodore C128, Yamaha YIS503IIIR MSX2 & etc
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