On Tue, Jan 24, 2023 at 7:02 PM Adrian Godwin <[email protected]> wrote:
>
> On Tue, Jan 24, 2023 at 6:46 PM Tony Duell <[email protected]> wrote:
>>
>> >>
>> >> 1) There is a 5 pin DIN socket for connecting an external video
>> >> monitor. The signals seem to be TTL-level separate syncs at European
>> >> TV rates (15625Hz horizontal, 50Hz vertical) and separate (not
>> >> composite) 4-level analogue video.
>>
>> I know it well, but it is unlikely to be the monitor I am looking for here :
>>
>> It's colour (and the P2000C is clearly a monochrome output).While that
>> it no real barrier, I doubt Philips would have wasted a colour CRT in
>> that way
>>
>  I missed that. So it was pinned for colour but only used mono ?

The P2000C is a monochome system. The built-in monitor is a green
screen (P31 phosphor) 9" CRT. The terminal board can output 4
intensity levels, either for things like highlighted text or in
grpahics mode (there's 256*252 in 4 levels or 512*252 in 2 levels).
The video output socket is essentially the same signals as go to the
internal monitor, although separately buffered.

There re 5 pins on the video socket. They are (in some order)
Ground
Horizonal Sync
Vertical Sync
Analogue Video
and, I think, dot clock.

No colour at all.

> There was another Philips monitor in the same or similar case. I've seen it 
> in both Green and Amber phosphors. This was also used on the Beeb when colour 
> was too expensive. I can't remember the number now though.That was almost 
> certainly composite though - but it was such a common monitor it's quite 
> possible there was a separate-sync version.

My thought is that having provided this rather unusual video output,
they would have produced a monitor for it. But while I can find
minimal details (like it was a 12" CRT), I can't find a model number
mentioned anywhere. Nor any web page that shows it.


>>
>>
>>
>> Is it 12"? Something is telling me it's a 14" CRT but I am not gong to
>> dig mine out to check. The service manual implies it is over 12"
>> diagonal.
>>
>
> You're right. Mine has 13" visible so probably a 14" tube. And although the 
> mono might have been smaller, that case shape is so embedded in my memory 
> that I think they must have been 14" too - a 12" version would have looked 
> amusingly miniaturised.

The CRT is an M34EAQ10X according to the CM8833 service manual. The
'M' indicates a colour screen and he '34' is the diagonal in cm I
think. So about 13.3"

To be honest I find the 12" monitor for the P2000C somewhat odd. It's
not a major size increase over the intenral 9" thing. I would have
thought a much larger monitor, e.g. to show to a group, would have
been more use.

-tony

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