Date   : Thu, 24 Dec 1998 21:21:45 GMT
From   : bbc-list@... (Theo Markettos)
Subject: Re: BBCs in Canada

On Thu, 24 Dec 1998 18:10:12 +0000, stuart@... said:

> In message <36825039.E6811977@...>, Chris Richardson
> <chris@...> writes
> >Does anyone know anything about BBCs shipped to Canada? 
> Canada and the US have a different TV standard (NTSC, not 512 line PAL
> as in the UK).  NTSC works at 60Hz and has fewer horizontal lines.
> Therefore the BBC screen had to be shrunk vertically by a few lines in
> each mode for it to fit.

I think it's possible to modify a UK BBC to US spec - I've done the reverse
modification.  You need to swap the modulator for a UM1622, and the 17.7 MHz
crystal for a 14.318 MHz variety, and change a few links (I've got the
details for a US board if anyone's interested).  I'm not sure how things
would work with UK ROMs, but I think US ROMs would break quite a few things,
like games which assume the layout of screen memory.  IIRC they did give a
few extra K of user memory, which might have come in handy...

> A special version of the OS was produced by
> Acorn to do this, together with a version of BASIC where the keyword
> COLOUR was spelt COLOR

AFAIK both UK and US BASICs accepted COLOUR and COLOR, just the UK manuals
documented COLOUR and the US manuals documented COLOR. I think they share the
same token, so the US version lists programs with COLOR and the UK with
COLOUR.

> (Very considerate of them as I recall none of the American computer
> manufacturers bothered to do the reverse!).

It's especially annoying in so-called International Standards, like HTML and
VRML.  I've got particularly sick of writing { diffuseColor .... } all over
the place in VRML...

> >Canada uses a
> >voltage of 110 v at 60 cycles.
> Just like the US.

All the BBC PSUs I've seen have a 230/115 link inside, which should be easily
movable.  As it's a switcher, I think it should be fairly tolerant of
frequency.

> >Any suggestions as to how someone in Canada could use a real BBC?
> Even if you get a UK BBC working, you're still going to have problems
> displaying the output.  You'll probably also need a PAL TV or UK Monitor
> converted to work at 110v 60Hz.

I don't think monitors take their scan rate from the mains (there's too much
short-term fluctuation), so if you can get a suitable transformer you should
be able to use a UK monitor without changing its scan rate.  Alternatively,
try finding a multisync over there that can scan down to 15KHz (until
recently many Acorn multisyncs could), and that should work without any
hacking.

Merry Christmas!
Theo

-- 
Theo Markettos          theomarkettos@...          
Liphook
Hampshire               Web site, including Acorn backup software
UK                      http://www.marketto.demon.co.uk/