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Author Topic: Recreate the CPC?  (Read 4555 times)

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Offline dcdrac

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Recreate the CPC?
« on: 01:24, 25 November 15 »
Would it be horrendously expensive to recreate the CPC from the 664 onwards with the plus capabilities built in and with all the expansion boards that have come out recently, and to have it all in one box?

Offline ||C|-|E||

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Re: Recreate the CPC?
« Reply #1 on: 01:29, 25 November 15 »
It depends of what you want to do to recreate the machine. If it is something like a super-emulator running in a small device it would not be expensive at all; if it is with a FPGA I guess that it would be reasonably cheap but a lot of effort would be needed in order to make it to behave 100% like an original Amstrad with all the expansions. If we are talking about a completely new device that has the Plus capabilities it could be more complicate because the ASIC is, to my current understanding, not easy to implement by hardware de novo and very very difficult to buy. If it was a "normal" 6128 it would be easier, in fact, Just CPC is quite similar to that...

http://www.sellmyretro.com/offer/details/Just-CPC,-amstrad-CPC-clone-PCB-board.-4212

For sure, the hardware experts in the forum will be able to shed more light in the question than me  :)

 
« Last Edit: 01:31, 25 November 15 by ||C|-|E|| »

Offline Munchausen

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Re: Recreate the CPC?
« Reply #2 on: 03:36, 25 November 15 »
*hmmm*



Offline TotO

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Re: Recreate the CPC?
« Reply #3 on: 07:35, 25 November 15 »
Would it be horrendously expensive to recreate the CPC from the 664 onwards with the plus capabilities built in and with all the expansion boards that have come out recently, and to have it all in one box?
Not from the 664... But, a 6128 with most existing expansions embedded, yes for around 100€.
By the way, the PLUS capabilities are not interresting at all... They are limited colours display with fake sprites and bugged DMA.
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

Offline CraigsBar

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Re: Recreate the CPC?
« Reply #4 on: 07:38, 25 November 15 »
Not from the 664... But, a 6128 with most existing expansions embedded, yes for around 100€.
By the way, the PLUS capabilities are not interresting at all... They are limited colours display with fake sprites and bugged DMA.
In your opinion. I however disagree. Please do not turn every thread that mentions the plus into a reason to start your one man plus bashing crusade.

Offline TotO

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Re: Recreate the CPC?
« Reply #5 on: 10:33, 25 November 15 »
The thread title is "Recreate the CPC", and it is exactly what I does. So, excuse me to answer if I don't meet all requirements.  :-\
My design include something like  X-MEM, X-MASS, PlayCity and more... Parts can be reused to save money and free the expansion slot.

It is not my fault if you goes touchy each time I spoke about the PLUS capabilities. I own it and what I said is not new.
If the graphic side is improved, it should be better. (fine if it is compatible, but it mustn't be a limitation for me)
« Last Edit: 11:01, 25 November 15 by TotO »
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

Offline CraigsBar

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Re: Recreate the CPC?
« Reply #6 on: 10:49, 25 November 15 »
The original post includes "with plus features" your reply with "the PLUS capabilities are not interesting at all" was totally unnecessary and you well known thought on the plus are irrelevant to this thread.

Sent from my A3-A30 using Tapatalk


Offline TotO

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Re: Recreate the CPC?
« Reply #7 on: 10:51, 25 November 15 »
It is my point of view and I explain why... He don't need to take acount of that. Nor you.
« Last Edit: 11:00, 25 November 15 by TotO »
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

Offline Munchausen

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Re: Recreate the CPC?
« Reply #8 on: 11:02, 25 November 15 »
Wow a lot of disagreements on these boards of late, everyone is a bit touchy. Come on, we are all here because we love the CPC! Play nice!

I've thought about a different angle - recreate the CPC by implementing some of the obsolete parts with CPLDs. The plan would be first to build a plug in replacement for the CRTC, as there is an implementation already available. Then you would need to do the gate array in another CPLD  (and a D2A). Then integrate the other logic on the mainboard in another CPLD. Eventually you can build a much smaller CPC, with a smaller z80 processor, a PLCC FDC9266 (smaller and doesn't need a data separator), one or two RAM chips instead of 16, and most other parts in small packaging CPLDs. You can integrate other peripherals, and it should be possible to overclock the whole system significantly. Finally, you could look at adding other features to the gate array.

The biggest hurdle is the gate array implementation.

Offline TotO

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Re: Recreate the CPC?
« Reply #9 on: 11:06, 25 November 15 »
It is close to what I am doing, except that I meet a 6128 form factor.
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

Offline Bryce

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Re: Recreate the CPC?
« Reply #10 on: 11:07, 25 November 15 »
All possible, although it would be a massive amount of work to do this. If it was some extremely rare computer I'd be with you, but the CPC is still readily available.

Bryce.

Offline Dr Tiger Ninestein

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Re: Recreate the CPC?
« Reply #11 on: 11:11, 25 November 15 »
I ask this as somebody with absolutely zero tech knowledge, but how come the ASIC chip can't be recreated/reproduced?


I know that if you buy a plus with a duff ASIC, the computer is pretty much worthless as it is the one part that isn't available.


Surely with the knowledge/talents that you guys have, it is doable?

Offline Munchausen

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Re: Recreate the CPC?
« Reply #12 on: 11:53, 25 November 15 »
If you followed the way I described, you could implement the plus features of the ASIC with a CPLD - in the gate array (and perhaps needing some extra stuff in the CRTC, not sure about that one).

As Bryce said it's all possible, but it's a silly amount of work. As I said, reimplementing the gate array is the crux of the problem. The rest is still a massive amount of work, but it's more obvious how to do it.

Offline TotO

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Re: Recreate the CPC?
« Reply #13 on: 11:57, 25 November 15 »
Exactly.
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

Offline robcfg

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Re: Recreate the CPC?
« Reply #14 on: 13:56, 25 November 15 »
I know some guys at the MESS forums that are specialist decapping and taking high res pictures of the circuits inside.


Would that be useful to decipher the inner workings of the GA? Because it may be worth to sacrifice 3 GA's to gain full understanding of them.


What's your guess?

Offline Bryce

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Re: Recreate the CPC?
« Reply #15 on: 14:25, 25 November 15 »
Do they also do the reverse engineering of the silicon or just take the pictures? Because that's the difficult bit.

Bryce.

Offline ||C|-|E||

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Re: Recreate the CPC?
« Reply #16 on: 15:03, 25 November 15 »
With hi-resolution electron microscopy data of a chip like the ASIC is actually possible to fully do the reverse engineering, but one thing is "possible" and another is "viable" or "cheap" :) . If my memory does not fail, I recap that it has been done for the SNES in order to achieve perfect emulation and it would also work great for a FPGA implementation. On the other hand, as Bryce said, reverse engineering from the pictures is difficult and fabricating a new chip from the info, although possible, is probably out of the scope of a particular person unless he or she is really rich. Good news is that this could probably be done using dead ASICs, because it is unlike that all of them are dead due to the same reason.

Funnily enough, in the lab we usually do this kind of job to reconstruct atomic models of protein complexes (that are way smaller that the smallest chip) but the amount of money and time that is spent in the process is quite crazy. The ASIC would be easier to image and map, though  :D
« Last Edit: 15:09, 25 November 15 by ||C|-|E|| »

Offline Munchausen

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Re: Recreate the CPC?
« Reply #17 on: 15:41, 25 November 15 »
I actually looked into the state of the art in this domain a while back. What they used to do was print the picture in a giant size on many pieces of paper, and lay it out on a very large floor. Then engineers go around and draw out each transistor on top of the photo (there are some pictures of people doing this on the net somewhere). Next it has to be entered into a computer. These days there are tools that can do some of the transistor identification automatically, but they are far from perfect and there is still a lot of manual work involved. It takes a long time, and while there are companies that will do it for you, it is not the sort of thing that those in the community could afford.

EDIT: of course you can do it yourself if you have the pictures too. But it the sort of job that will take you years. There were some guys who did it for an acorn ULA, and they have built some custom tools to help. Look here if you want to see what a nightmare that is! stardot.org.uk/forums/viewtopic.php?t=8539
« Last Edit: 15:46, 25 November 15 by Munchausen »

Offline Bryce

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Re: Recreate the CPC?
« Reply #18 on: 16:46, 25 November 15 »
It should also be mentioned, that while these techniques are quite good for digital circuitry, reverse-engineering analogue silicon is pretty much impossible.

Bryce.

Offline Munchausen

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Re: Recreate the CPC?
« Reply #19 on: 17:15, 25 November 15 »
Also I forgot that the topic I linked to is reverse engineering from an original blueprint of the chip die, which is much easier than doing it from a photo.

Offline TFM

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Re: Recreate the CPC?
« Reply #20 on: 19:11, 25 November 15 »
IMHO it's important to stay compatible to existing hardware. True for the 6128 part, for the X-cards part. And sorry imho also true for the Plus part if doable. Ok, a lot of things could have done better in the Plus for todays 2015 perspective and maybe even from 1992s POV. However it is like it is. Really! Let's stay compatible! It's great to add new features, but please after being compatible.  :)
Even if only a part of the Plus gets emulated (colors, softscroll, rasterinterupt) it would be great.
About the Plus sprites: If they get implemented, then we can easily expand them from 16 colors (4 bits per byte used) to 256 colors (all 8 bits used) at (nearly) no cost. If you want add a pointer that points to somewhere in the 576 KB first RAM and you have real sprites.


I pledge for compatibility and expansions.  :)


Let's not be misguided by personal likes or dislikes, such a project would be too big for that.  :) :) :)
TFM of FutureSoft
Also visit the CPC and Plus users favorite OS: FutureOS - The Revolution on CPC6128 and 6128Plus

Offline Trebmint

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Re: Recreate the CPC?
« Reply #21 on: 22:28, 25 November 15 »
I agree totally with TFM. If you did this then you need everything. And the Plus is more necessary than say PlayCity etc, as it has software already. And then adding more to the ASIC via use of a byte rather than nibble to get 256 colours, or extra palettes, and pointers to allow far more flexibility would turn our plus plus into something amazing

Offline CraigsBar

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Re: Recreate the CPC?
« Reply #22 on: 22:46, 25 November 15 »
I agree totally with TFM. If you did this then you need everything. And the Plus is more necessary than say PlayCity etc, as it has software already. And then adding more to the ASIC via use of a byte rather than nibble to get 256 colours, or extra palettes, and pointers to allow far more flexibility would turn our plus plus into something amazing
Hell yes, that'll do me too. Who's building it?

Offline TFM

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Re: Recreate the CPC?
« Reply #23 on: 23:08, 25 November 15 »
I love PlayCity and it's new standard now too. But adding it won't be a problem imho.  :)
TFM of FutureSoft
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Offline Trebmint

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Re: Recreate the CPC?
« Reply #24 on: 23:15, 25 November 15 »
Yep shame that our best hardware guy doesnt like the Plus.