Date   : Wed, 07 Jan 2015 07:39:28 -0000
From   : rgcolem.myorg@... (Rob Coleman)
Subject: Compromises

J.G. Hartson wrote:
> Actually, I'm surprised nobody ever produced a palette extended that you
> could plug into the video ULA socket - but then the RGB outputs from the
> video ULA are conditioned to digital levels, and there's no easy way to
> bypass that circutry to get to the video output stage.

I'm pretty sure they did. There was the PaletteMate from Wild Vision which 
was
advertised in Acorn User and a similar device from Saturn Computers that was
reviewed in Micro User. I think that both allowed the 16 colours in mode 2 
to be
independently chosen from a palette of 4096.

However, both devices came out fairly late on (after the Master was 
released) and
I've never come across either of them in the wild.

I tried to contact Pete Wild a while ago to ask if he still had details 
about the
PaletteMate but didn't hear anything back.

There was also the Chameleon that Mike Cook designed but that plugged into 
the
User port and only mapped the 8 colours of the RGB output. I've built one of 
these
and it works well but being able to have 16 non-flashing colours would be a 
real
improvement.

I did think about using an FPGA/CPLD to replace the video ULA and extend the
palette but quickly realised that my limited knowledge of VHDL isn't up to 
the job!

I think we sometimes forget how good the Beeb's graphics capabilities were 
in
1981. They were certainly a huge improvement over the ZX81 which I had at 
the
time. It is a pity that Acorn didn't improve things with the Master although 
the Arc
was just around the corner.

Rob