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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 17th Jun 2010, 3:11 pm   #61
repairman 1234
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Default Re: Sinclair zx spectrum

Got the new Spectrum, this one works very well!!!

Have just loaded up Flight Simulator and played it without a problem....ooh, those graphics are cutting edge

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Thought since i had a known good tape deck and leads etc that i may as well try it all out with the old Spectrum to see if i get anything different.

Loaded up flight sim and all looked well, it asked me if i wanted take off, landing or flight and the i got a Y/N option for crosswind as i should, i selected N and it threw me back to the Sinclair start up logo!

I tried a smaller program and got a fail note (memorytop 1:1) and another game that loaded then froze just as it had been doing before.

I had the unit stripped earlier and i have pulled the ULA and refitted it incase of poor connections (noticed it is running very hot)

I still have to retension the plug sockets for ear and mic.

So i have one worker and one non worker (it is always very nice to have a spare) But would like to see it work again!
Is the ULA meant to be this hot?
Can i narrow down which IC will be the problem one?

At least i can rule out everything other than the computer itself now.

I now have a huge boxful of software to wade through, hundreds of titles!
I love digging into a big box full of old electronic gear

Thanks to all who have helped so far
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Old 17th Jun 2010, 3:58 pm   #62
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Default Re: Sinclair zx spectrum

IC15 holds the "units" bits of addresses 8000 to FFFF hex, so that's the one to look at. (The upper memory ICs are each 32K locations * 1 bit.)

It doesn't guarantee that there isn't another problem with a different bit at a higher address, of course. But you'll have to cross that bridge when you come to it.

As for where to get suitable memory ICs: you might be able to pull some from things like CGA or Hercules graphics cards, 1980s home computers or memory expansions for same. I've a feeling that 4164s can be used instead of 4532s; you'll waste half the capacity, but it's not like RAM is expensive anymore (long-since obsolete ICs excepted). You could even bodge in a single 62256: that is 32K * 8 static RAM. (It won't mind being refreshed!) They only need to have 250ns. access time. Even 30-pin SIMMs might be usable.

Spectrum ULAs do run hot, as they are not CMOS devices.
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Old 17th Jun 2010, 4:42 pm   #63
repairman 1234
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Default Re: Sinclair zx spectrum

Hi AJS,

Many thanks for all your help on this one
I will have a look around to find any IC's that may do the job (or maybe a scrap unit)

Hope to end up with two workers one day!!


Thanks again,

Chris.
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Old 19th Jun 2010, 1:03 am   #64
repairman 1234
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Default Re: Sinclair zx spectrum

Just as an update chaps,

I have just bought another one tonight!! This one has a faulty keyboard (the idea is two get my duff one working by either swapping the keyboard over or by pulling the ic out of it that i need.)

So fingers crossed i will soon have two good boxed workers and one spare unit to add to my collection, as well as a huge boxful of software

Then onwards and upwards to the BBC maybe!


Cheers,
Chris.
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Old 19th Jun 2010, 7:59 am   #65
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Default Re: Sinclair zx spectrum

You have all the excitement and enthusiasm of a youngster 30 years ago with his new Speccy.. have fun.
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Old 19th Jun 2010, 10:36 am   #66
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Default Re: Sinclair zx spectrum

Quote:
Originally Posted by G8VAT Wolfman View Post
You have all the excitement and enthusiasm of a youngster 30 years ago with his new Speccy.. have fun.
THANKS!!!

I Have been slowly working my way through some of the games...brilliant!
Now all i need is to feel like i did 30 years ago
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Old 2nd Jul 2010, 2:41 pm   #67
repairman 1234
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Default Re: Sinclair zx spectrum

Just a quick update.....

I have the cheap unit with the faulty keyboard now and have tested it and changed over the keyboard for the good one from my faulty unit.

So i now have two good condition boxed workers with a mountain of software and a spares unit with a faulty memory ic and a duff keyboard.

Thanks very much indeed to all who have helped me with this project!
As always, this forum is top notch!!

Next up could be a Beeb, and my knowledge of the Beeb is as compehensive as it is for the Speccy (non existant)

Thanks again!
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Old 4th Jul 2010, 8:45 am   #68
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Default Re: Sinclair zx spectrum

Excellent news. I must get my ZX81 with a cracked keyboard ribbon cable out and get it going.

Luckily the BBCs have plenty of service information freely available too, and the circuit isn't too difficult to understand.
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Old 4th Jul 2010, 1:21 pm   #69
David G4EBT
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Default Re: Sinclair zx spectrum

Spare keyboard membranes and other bits and pieces of hardware and software for the Sinclair computer range (ZX81, Spectrum, QL) are available from the link below - prices look reasonable:

http://www.rwapsoftware.co.uk/membranes.html

Worth a look.

David
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Old 4th Jul 2010, 3:19 pm   #70
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Default Re: Sinclair zx spectrum

Or just buy 40 tactile switches (they are dirt cheap nowadays if you know where to look), some breadboard and ribbon cable, and build an improved keyboard.

I haven't tried this (need a trip to my parents' attic first .....) but I'm sure one channel of a 4066 can be used to simulate a keypress, so you could get one switch effectively to operate two keys -- this should be more reliable than a 2-layer membrane. e.g. suppose you wanted single keys for "EDIT" (caps + 1), "LEFT" (caps + 5) and "RIGHT" (caps + 8). Use S1 to simulate the key "1", S2 to simulate "5", S3 to simulate "8", S4 to simulate caps shift; and diodes to ensure that S4 gets turned on along with any of S1, S2 or S3.

Apropos of nothing, has anybody else noticed that the Spectrum cursor keys are in the same order (left, down, up, right) as the direction keys in the vi editor?
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Old 4th Jul 2010, 6:03 pm   #71
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Default Re: Sinclair zx spectrum

I was just going to cut the cracked membrane ribbon, unsolder the socket from the PCB and solder in a length of ribbon cable to move the socket up to where the membrane now reaches. But thanks for the link, if the membrane shatters any more when I get round to doing the job, I might just buy a replacement.

Maybe it's my ZX81/Spectrum years that meant I fell naturally into becoming a vi user. I use vi (well, gvim) even when using Microsoft Powershell at work these days!
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Old 5th Jul 2010, 6:09 pm   #72
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Default Re: Sinclair zx spectrum

Often on keyboard Matrix controllers you can use a couple of diodes to make connect lines to a combo key, simpler than 4066s
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Old 15th Jul 2010, 1:32 pm   #73
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Default Re: Sinclair zx spectrum

Godness i used to have a speccy, thats going back a bit. I had the dreaded ZX81 then really upgraded to the rubber keyboard job with Wow Colour, remember the 16k ram pack for the ZX81, type in a programme, it wobbled or moved so you had to start all over again happy days Eh ...........Tha can allus tell a Yorkshireman.... but tha can't tell 'im much...... So very true ...........................i hope you get loads of fun from your speccy......... kind regards Alan.
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Old 11th Aug 2010, 8:13 am   #74
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Default Re: Sinclair zx spectrum

Many Spectrum emulators such as Spectaculator, will regenerate all the original loading sounds from TZX images. So one can either connect the Speccy to the speaker output of the PC, or one can make MP3s and load the Speccy from an iPod/MP3 player. I've found Speccys will usually load very reliably using this method, as there is no dropout, speed variation, wow/flutter and head alignment issues which are usually associated with cassettes.

BTW there are thousands of softwares and games on http://www.worldofspectrum.org/ in the TZX format.
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