Questions about the Memotech MTX that you were too afraid to ask...

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gunrock
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Re: Questions about the Memotech MTX that you were too afraid to ask...

Post by gunrock »

Yeah, I think I get it. Thanks Bill and Martin for the illuminating answers.
Steve G
Danish Memotech MTX 512, MFX and loving it
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gunrock
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Re: Questions about the Memotech MTX that you were too afraid to ask...

Post by gunrock »

Potholepete wrote: 26 Aug 2022 14:19 Here's a question that anyone who has had to work on them will know all too well....

Why did Memotech make working on the FDX so fiddley? I have had to take three apart due to power cap failure and lost count of the number of cuts and scratches my arms and hands have taken in the process... ;-)
So Jim, having never seen one FDX "in the flesh" (let alone three!), what are they made of? Are they aluminium like the MTX or more your usual rolled steel, like a cheap PC case? Is that what is causing the cuts?
Steve G
Danish Memotech MTX 512, MFX and loving it
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Dave
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Re: Questions about the Memotech MTX that you were too afraid to ask...

Post by Dave »

FDX disassembly info here, it shows the FDX construction and why working on one is such a pain!

http://www.primrosebank.net/computers/ ... sembly.htm
stephen_usher
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Re: Questions about the Memotech MTX that you were too afraid to ask...

Post by stephen_usher »

The only time I saw FDX units was at the "Your Computer Show" at Olympia in 1984.
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gunrock
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Re: Questions about the Memotech MTX that you were too afraid to ask...

Post by gunrock »

stephen_usher wrote: 30 Aug 2022 19:54 The only time I saw FDX units was at the "Your Computer Show" at Olympia in 1984.
I might have been to that one, or it might have been the PCW Show - that was at Olympia, too.

http://www.computinghistory.org.uk/det/ ... mber-1984/

Can't remember ever seeing Memotech machines there, but I was fourteen and with a load of teenage reprobates more interested in nicking anything that wasn't nailed down, unfortunately. :roll:
Steve G
Danish Memotech MTX 512, MFX and loving it
stephen_usher
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Re: Questions about the Memotech MTX that you were too afraid to ask...

Post by stephen_usher »

Question: Were any HDX units ever built and if so did any get sold?
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Dave
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Re: Questions about the Memotech MTX that you were too afraid to ask...

Post by Dave »

Don’t know if any were actually sold, but at least one was built.

I came across the guy that owned it in around 2009, but by the time that I knew about it, it had been sold to some guy in South Africa and from then, it’s been untraceable
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1024MAK
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Re: Questions about the Memotech MTX that you were too afraid to ask...

Post by 1024MAK »

gunrock wrote: 24 Aug 2022 14:47 Why did Memotech pin the composite out to monochrome on quite a few MTX machines?
Apart from extra protection against stalking…

A monochrome composite video signal can have a higher resolution compared to a colour composite video signal. That’s why the Acorn BBC B, Electron and BBC Master 128 machines had a (default from factory) monochrome composite video signal output.

And yes. Obviously a monochrome monitor was substantially cheaper than a colour monitor. Especially if you wanted a high resolution type (there is no shadow mask in a monochrome CRT, and the design of the tube neck, focus, horizontal and vertical scan coils are far less complex). Oh, and there is only one video channel/driver stage (you need three in a colour CRT).

For all these reasons, “professional” work was normally done on monochrome monitors (green screen being by far the most common).

But for the actual exact reason, well, you would have to ask the relevant person from the company…

In terms of the addresses used for any address decoding (be it memory or I/O devices), to keep costs down and to not have unnecessary propagation delay, yes, you normally want the decoding logic to be as simple as possible. Hence normally it being a factor of 2 due to, well, binary logic…

But they used full (more or less) I/O decoding, and hence used 74LS138 3 to 8 line decoder chips. Then ANDed the Y1 and Y2 outputs. So actually the hardware is not overly complex. Far better than the mess of the ZX Spectrum…

Mark
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gunrock
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Re: Questions about the Memotech MTX that you were too afraid to ask...

Post by gunrock »

1024MAK wrote: 04 Sep 2022 01:59 Apart from extra protection against stalking…
It's not working! :lol:
Steve G
Danish Memotech MTX 512, MFX and loving it
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gunrock
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Re: Questions about the Memotech MTX that you were too afraid to ask...

Post by gunrock »

Question: Why hasn't anyone produced a modern copy of Speculator?

This community is still thirsty for software and the Spectrum has tons. Dave, I know, has a Speculator and so do others here probably. Tony Brewer, the developer, is part of the community and would maybe provide "spiritual guidance" (for want of a better term), so why haven't we created a Speculator+ or SpeculatorNG?

I think Andy Key's Rememorizer had Speculator functionality, so there doesn't seem to be an intellectual property objection, as far as I can see.

No appetite for Spectrum games? Or are the limitations of the Speculator producing a sub-standard experience when compared to a real Spectrum/Spectrum emulation/modern re-imaginings like the Spectrum Next, etc?
Steve G
Danish Memotech MTX 512, MFX and loving it
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