Date   : Tue, 19 Apr 2011 13:38:21 +0100
From   : afra@... (Phill Harvey-Smith)
Subject: making replica acorn cards

On 19/04/2011 13:11, stuart wrote:
> The whole idea of making a replica is that it is as close to the
> original as possible. If somebody has a system with a faulty card
> then being able to obtain a replica of that card might allow them to
> keep the system as they want it, and to the untrained/unknowing eye
> it would seem still in mint condition.

I guess, depends I suppose if your focus is functionality or form :) :)

> Why stop there. Almost any 80's computer can be done in an FPGA
> these days so why bother with more than one chip for any clone?

Well I guess that's also true, and has also been done in the Acorn world
with AlanD's Electron in FPGA.

> In fact why bother with chips when a modern PC can emulate the whole
> machine. These are different things than having an original system
> that has a faulty part than can be replaced.

Between hardware solutions and emulation yes, but from a functionality
stand point if the modern hardware equivelent was a functional
equivelent (no mater how it was implemented), then the system should
behave the same, even if it's not an exact copy.

The real problem comes where you have ULAs which are now unobtainable, 
the only real course of action you have is to replicate them with LS / 
CPLD / FPGA etc

>> In some cases the chips are harder to find / more power hungry
>> than more modern replacements.
>
> Yeah, but the old PSUs should have been built to cope with the
> demands asked of them.

Cough Atom regulators cough, on a fully loaded Atom they whrere 
notorious for getting too hot, I have one Atom case that bears the signs 
of this......though to be fair this is prolly not a problem with the 
system computers.

>> As for copyright/patent/trademark then possibly posibly not and if
>> they are still covered, finding out who actually owns the rights
>> could be somewhat challenging.
>
> And that sounds to me like I would be better off waiting till
> somebody comes out the woodwork as demands some money.

Indeed, though to come after you they would need to proove that they
held the rights so prolly not going to happen.

[Snip ex-acorn people]
> I can understand that. Both of them have moved on, but it appears
> that some of use choose not too.

Indeed, as has been pointed out several times, the beauty of the old 8
bit stuff, is that it's simple enough for one person to understand the
whole system, hardware, firmware and software, I doubt many people could
claim that with a modern PC.

>> Possibly, I did wonder about building a System clone, main problem
>> seems to be getting a eurocard backplane for a sensible price.....
>
> They do seem to be funny money for what is only a long PCB. Not sure
> how to get around that one as I have no idea how much such a PCB
> would be if made to order today.

Well the actual board would be simple enough, and could even be single
sided.....it's the whole cage shebang that seems to be the expensive bit.

> I have used Eagle for many years (both at work and at home) so would
> probably do the designs in that. Other good reasons are that Eagle
> is available on most modern platforms and newer version will open
> older designs, not always the case with commercial packages!

Indeed, and one of the advantages is that the freeware version can still
open and view / print / output designs produced with the hobby or
profesional versions, which is a definite advantage.

Cheers.

Phill.