Homebrew Sinclair QL ?

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Paul
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Re: Homebrew Sinclair QL ?

Postby Paul » Wed Mar 02, 2016 10:47 am

vanpeebles wrote:Hello, how come you two are both 66? :D

Maybe both are going to be 50 this year :?


Paul
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Re: Homebrew Sinclair QL ?

Postby Paul » Wed Mar 02, 2016 10:51 am

I just realize this discussion is in the Hardware Forum.
As I am not developing anything in this direction my posts should actually be better placed in the general chit and chat area of this forum.... :oops:


Harry66
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Re: Homebrew Sinclair QL ?

Postby Harry66 » Thu Mar 03, 2016 9:47 am

There’s two ways that people seem to look at homebrew Computers…

1. Using modern components Like FPGAs and stuff possibly combined with original CPU.. this is probably the easiest and most straightforward. Especially if you’re good at programming FPGAs
2. The Old School method of using old Legacy ICs to give an authentic Retro feel. This method however needs a lot of effort prototyping on breadboard before designing a PCB and stuff.

I suppose it comes down to which way you prefer !


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vanpeebles
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Re: Homebrew Sinclair QL ?

Postby vanpeebles » Thu Mar 03, 2016 9:53 am

Paul wrote:I just realize this discussion is in the Hardware Forum.
As I am not developing anything in this direction my posts should actually be better placed in the general chit and chat area of this forum.... :oops:


I was just asking as both accounts were activated at the same time, and I didn't want to be activating two accounts if they both belonged to one person :D


GrumpyOldQLuser
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Re: Homebrew Sinclair QL ?

Postby GrumpyOldQLuser » Mon Mar 07, 2016 1:47 pm

A homebrew, self build QL sounds like a good idea , if it can be made ??


GrumpyOldQLuser
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Re: Homebrew Sinclair QL ?

Postby GrumpyOldQLuser » Mon Mar 07, 2016 4:16 pm

As there's not an awful lot of ICs inside a QL it can't be too hard to build a Homebrew QL ?

68008 CPU still available
SRAMs to replace DRAMS
ZX8301 on CPLD with DACs for RGB composite video
ZX8302 on CPLD
intel 8049 still available

I'm sure all the rest of the Bits and Bobs can still be sourced !

but I suppose this is easy for me to say


MIST
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Re: Homebrew Sinclair QL ?

Postby MIST » Thu Jun 02, 2016 9:40 pm

Sounds like a great idea. I'd go for something as close to the real thing as possible. Just replace the Ula's with cplds and the micro drives with a ql-sd clone. The 8049 will need some help of e.g. a small avr or pic controller to deal with a ps2 keyboard.

Go for it!


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Pr0f
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Re: Homebrew Sinclair QL ?

Postby Pr0f » Wed Nov 15, 2017 1:33 pm

Did anything come of this?

A DIY QL, but with maybe some of the shortcomings of the original machine addressed - such as the serial ports.

Then there is the question of video output - old monitors and TV's with aerial inputs getting rarer.

And Microdrives - do you ditch them?


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Peter
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Re: Homebrew Sinclair QL ?

Postby Peter » Thu Nov 16, 2017 10:41 am

Pr0f wrote:A DIY QL, but with maybe some of the shortcomings of the original machine addressed - such as the serial ports.

Once you want some shortcomings addressed, the question where this ends, always comes up! This has been the same in the QL scene for three decades. :D

Even memory expansion, or not having microdrives, definitely breaks compatibilty with various old software.
For timing-dependant stuff, even SRAM instead of DRAM.

While on the other hand, resembling the Original QL closely might be the only point of such a 68008 hardware!

Replacing ZX8301 and ZX8302 with PLD seems natural, but will bring up the question how large the PLD should be. Doesn't take much, and a little FPGA is near.

Pr0f wrote:Then there is the question of video output - old monitors and TV's with aerial inputs getting rarer.

A big question indeed. I know that some had luck with VGA and HDMI converters. But I never achieved a good result with my original QLs. With HDMI never a stable picture at all, and with VGA only unsharp picture after 5 minutes of warming up, using a large converter board that gets hotter than the QL.


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Pr0f
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Re: Homebrew Sinclair QL ?

Postby Pr0f » Thu Nov 16, 2017 11:05 am

I'm planning on putting something together - and it will almost certainly cause compatibility issues with some software, but as my interests lie more on the hardware side, that doesn't cause me too much of a headache.

That said, I would seek to try and maintain full compatibility at the super basic level, and anything that uses the standard qdos calls and screen handling should be fine. I wanted to put something back in my empty QL case, and have a hankering to try out a few hardware adaptations and possible new hardware like TCP/IP and USB.

I have seen some great ideas on the forum here, it would be nice to get something tangible to explore them.

I get what you say about CPLD and FPGA. I like the design of the original QL, but you can really see the compromises made to get it out of the door.

Anyway, it 's a non commercial adventure for me - hopefully arriving at a test bed that others could pick over for ideas...



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