cant enter code or load game on ZX Spectrum 48k

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Jake17500
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cant enter code or load game on ZX Spectrum 48k

Post by Jake17500 » Sat Sep 15, 2018 5:38 pm

Recently purchased a ZX Spectrum from eBay for my Dad (he had one as a kid) and have been trying to get it working for him. I have it connected to the TV and have been told it seems to be in full working order but I am unable to enter any code or load a game via a cassette player.

The spectrum is going straight to a screen with a smaller white box surrounded by a flashing red and blue border, it. If I connect the cassette player and play a tape with a game on it will do the flashing borders and noises (sorry for the lack of technical jargon) but won't, as it seems from youtube it should, show the name of the game in the white box and load it - once the tape has stopped playing it will return to how it had been previously. from what I have gathered it should be an all white screen with (C) 1982 Sinclair research at the bottom where I am able to type in code.

I expect this is a simple fix but I have no experience with spectrums and I can't seem to work out what's going wrong :(

If anyone is able to help I will be very grateful! (I have coding experience in VB.net and I am experienced with computers so I should be able to follow any advice you can give)
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Ast A. Moore
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Re: cant enter code or load game on ZX Spectrum 48k

Post by Ast A. Moore » Sat Sep 15, 2018 6:06 pm

Disconnect the power and connect it back. The Spectrum should reset and display the © 1982 message.

If it does and you can type the LOAD command (the letter J) followed by two double quotes and confirmed by pressing the ENTER key, then loading should commence after you press Play on the recorder. You may want to play around with the volume on the cassette recorder to get the level just right. You’ll need to use the earphone output, rather than line. Also, make sure you’re using a mono lead plugged into the EAR socket of the Spectrum. (It’s a little counterintuitive, but a good mnemonic is the phrase “lend me your ears.”)
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Every man should plant a tree, build a house, and write a ZX Spectrum game.

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Re: cant enter code or load game on ZX Spectrum 48k

Post by Jake17500 » Sat Sep 15, 2018 8:54 pm

ah just had to turn it on and off again!

It will now display an all white screen, no (c) 1982 message but that maybe that's my TV cropping the image from the spectrum? if I dont press anything for a little while the spectrum switches to the red and blue borders - does that sound like the right thing for it to be doing?

many thanks for the reply! :)
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Ast A. Moore
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Re: cant enter code or load game on ZX Spectrum 48k

Post by Ast A. Moore » Sat Sep 15, 2018 9:09 pm

Jake17500 wrote:
Sat Sep 15, 2018 8:54 pm
It will now display an all white screen, no (c) 1982 message but that maybe that's my TV cropping the image from the spectrum? if I dont press anything for a little while the spectrum switches to the red and blue borders - does that sound like the right thing for it to be doing?
No, it’s really not supposed to do that. Looks like you’ve got one sick puppy on your hands.
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Every man should plant a tree, build a house, and write a ZX Spectrum game.

Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.

Jake17500
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Re: cant enter code or load game on ZX Spectrum 48k

Post by Jake17500 » Sat Sep 15, 2018 9:17 pm

ah no! It is sitting on a screen which looks to be the same colour as the (c) 1982 screen but just with no message (I say it could be getting cropped as I have it connected to a modern Tv). typing doesn't show up either but if I play the game tape into the spectrum it will flash like its supposed to and make noises which I think sound like they are meant to, but it won't get every show anything in the white box in the centre of the coloured borders... I am currently trying some other tapes that I have in case the one I was trying is a dud, do you have any recommendations for how to troubleshoot the spectrum?
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1024MAK
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Re: cant enter code or load game on ZX Spectrum 48k

Post by 1024MAK » Sun Sep 16, 2018 7:47 am

Sorry Jake, your ZX Spectrum has a hardware fault.

Your TV may or may not be cropping the video image from the ZX Spectrum, but as the outer part of the displayed image from a ZX Spectrum is the border area, I think it to be unlikely that the TV is cropping such a huge amount of the screen image.

Secondly, the ZX Spectrum runs BASIC from ROM (Read Only Memory). BASIC is a machine code program that the CPU executes from ROM. After power up, it does a memory check. This is only designed to work out how much RAM (Random Access Memory that can be written to as well as read) it has. It is not a proper functional memory test. If the system detects a fault, it just freezes. But not all faults are detected, so the machine code program in ROM will continue, but, if there is a fault, the data it stores in RAM will be corrupted. The result can be that the CPU will jump to random places in the memory and various strange symptoms are the result. This can include the stripes in the border that look a bit like the same stripes that it displays when loading.

For normal operation, after the memory check, BASIC clears the screen to "normal" white (depending on the TV settings, it can look like light grey). It then prints the Sinclair copyright message at the bottom of the "text" window, but NOT at the bottom of the visible screen area. It then waits for the user to enter either a program line, or a direct command. During normal operation, it will not automatically switch to loading mode. It will ONLY load a program (for example a game) from tape (or what it thinks is a tape) after you have entered a LOAD "" or a LOAD "name" command.

When you play a tape (or equivalent), the signal is routed to the internal loud speaker independent of the CPU. So even if you remove all the digital chips, as long as it has power, it will still reproduce the audio signal from the tape.

From the symptoms that you have described, it appears that the most likely fault is a RAM chip having failed. But there are a number of other possibilities.

The good news is that it is very likely that it can be repaired. If you know someone who is good with a soldering iron and who works on electronics, ask them for help. Or we can point you in the direction of a specialist 1980s computer repairer.

YouTube examples:

Example of a power up / "boot-up"

https://youtu.be/CuoxxE4KUOY

Example of loading screen image from tape

https://youtu.be/MtBoRp_cSxQ

Example of loading a game from tape

https://youtu.be/V0EfycbDhiw

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Re: cant enter code or load game on ZX Spectrum 48k

Post by Jake17500 » Mon Sep 17, 2018 7:02 am

thank you for the detailed reply! I am glad to hear that the spectrum should be fixable! are you able to recommend an 80s computer repair specialist? I am in the south of england if that is any help in terms of a recommendation

again many thanks for the reply
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Re: cant enter code or load game on ZX Spectrum 48k

Post by 1024MAK » Mon Sep 17, 2018 8:48 am

ZX Spectrum repairers that I know of:- Plus no doubt, there are others.

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Jake17500
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Re: cant enter code or load game on ZX Spectrum 48k

Post by Jake17500 » Tue Sep 18, 2018 4:04 pm

thank you very much :)
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