Space problems in the UK and US

From: Tony Duell <ard_at_odin.phy.bris.ac.uk>
Date: Tue Oct 28 12:40:10 1997

On Tue, 28 Oct 1997 kevan_at_heydon.org wrote:

> Can anybody recommend a good universal monitor that can be used with a
> large number of home micros?

This seems to be becoming a FAQ here...

Some machines, like workstations _need_ their original monitor. Something
like a PERQ 3 has part of the keyboard/mouse interface in the monitor
stand. And the scan rates of all the PERQs are fairly non-standard.

Another case is when the original monitor is sufficiently interesting to
be worth preserving in its own right. One of my machines came with an ex
TV-company Barco and its service manual. That monitor is built like a
tank, gives a very good picture, and is a joy to work on.

But a lot of home micros seem to need one of 4 types of monitor, all of
them essentially hackable into each other, thankfully. In most cases, the
original monitor, if it existed at all (a lot of them plugged into a
normal TV set), is an uninteresting thing. The 4 classes are :

1) RGB at TTL levels (like CGA, but without the I line)
2) RGB at analogue levels
3) Composite colour video
4) UHF modulated colour video (TV RF signal).

Now, you can feed TTL level signals into an analogue monitor. I do it all
the time. If you are a purist you put resistive attenuators in the line to
reduce the 5V signals to 1V. But very few monitors seem to object

Some monitors will take either RGB or composite PAL inputs. Philips
make/made one. One of the Acorn monitors is that chassis without the PAL
decoder - one day I'm going to add the extra components, tweak it up, and
essentially upgrade it to the better model. It shouldn't take too long.

Velleman do a very nice (although expensive) PAL - RGB encoder/decoder.
It's called the K4600, and is available as a kit from Maplin. It works
well, it's quite small, and it's easy to put together. This is (IMHO) one
of the best ways to drive an RGB monitor from a composite output.

UHF outputs are a pain. I generally ignore them and tap the signal off
before the modulator. If you insist on not modifying your computers, then
you can use the tuner/IF strip from an old VCR to demodulate it. There
have been kits to do just that, but I've not seen one on sale for a few
years - Maplin _used_ to do one, but it's been discontinued, alas.

What about using a small (12", 14"), good quality portable TV? That would
give you the UHF input, composite PAL and RGB on the SCART socket, and
some of the better portables (i.e. _not_ a no-name piece of trash)
actually have decent CRTs in them and will display 80 columns quite
clearly from the RGB inputs.

>
> Also does anybody use TV tuner cards you can get for PC's? It seems
> like these could be very useful as they mean you need just one monitor
> on your desk. Any recommendations for the best cards?

Well, I doubt my PC would take one (all the slots are already full), my
video card certainly couldn't display the output, and most (all?) of these
cards don't come with drivers for my OS of choice. So I've not tried one.
I can't see the point - a PC is considerably more hassle to move onto my
workbench than a monitor...

>
> --
> Kevan

-tony
Received on Tue Oct 28 1997 - 12:40:10 GMT

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