VIDC output specs

[Ian K (N)]

Hello All

Can someone point me to a site or email me the video output specs for the
Risc PC. I need details on min frame and line rates etc and details of the
sync signals and their timing in the different modes and situations.

Thanks
Ian K


* Founder member of the East Fincley On Sea Codswollop Deprecation Society. ;-)

[Jess]

In message <4c0f09c47dnews@iank.org.uk>
"Ian K (N)" <news@iank.org.uk> wrote:
Can someone point me to a site or email me the video output specs for the Risc PC. I need details on min frame and line rates etc and details of the sync signals and their timing in the different modes and situations.

It's highly programmable. Running one of the utilities to make monitor
definition files (eg makemodes), should let you see details for
when using standard monitors.

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[Jess]

In message <4c114b377anews@iank.org.uk>
"Ian K (N)" <news@iank.org.uk> wrote:

[snip]
Although this is useful it doesn't give me enough info on what can actually come out of the port. The Risc PC Technical reference manual isn't detailed enough ether. I'm particularly interested in the support for using TV's as I am trying to drive a 1950's 405 line TV from it via an adaptor. I would use an Oscilloscope to analyse the output but I haven't got a suitable one at the moment. Also there doesn't seem to be any way of controlling Interlace from a Risc PC as far as I can find can anyone shed any light on this.

I've not heard of a lower limit for an RPC, (driving it at too high a
rate for a while might cause problems).

Couldn't you just create a 405 line mode (assuming someone hasn't
already) and test it?

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[Jess]

In message <f0299b114c.druck@druck.freeuk.net>
druck <news@druck.freeuk.com> wrote:
On 13 Jul 2003 "Ian K (N)" <news@iank.org.uk> wrote: Although this is useful it doesn't give me enough info on what can actually come out of the port. The Risc PC Technical reference manual isn't detailed enough ether. I'm particularly interested in the support for using TV's as I am trying to drive a 1950's 405 line TV from it via an adaptor. If you know TV signal theory, you can easily make any PAL compatible signal with am MDF.

He wants to make a 405 line signal, not PAL. I would expect that vidc
would have no trouble putting out lower sync rates (12kHz???), but is
this the case?
I would use an Oscilloscope to analyse the output but I haven't got a suitable one at the moment. Also there doesn't seem to be any way of controlling Interlace from a Risc PC as far as I can find can anyone shed any light on this. *TV 0,1 or get my AutoInterlace module from the top link below.

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[Martyn Fox]

In article <f0299b114c.druck@druck.freeuk.net>, druck <news@druck.freeuk.com>
wrote:
If you know TV signal theory, you can easily make any PAL compatible signal with am MDF.

How do you produce the 4.43361875 MHz colour subcarrier?

Martyn

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[Martyn Fox]

In article <d512c0114c.news@itworkshop.invalid>, Jess
<phantasm_39@hotmail.com> wrote:
He wants to make a 405 line signal, not PAL. I would expect that vidc would have no trouble putting out lower sync rates (12kHz???), but is this the case?

10.125 KHz to be precise.

(With a clearly audible timebase whistle!)

Martyn

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|\/| _ _ -+- _ |_ _ Windsor, Berks. UK
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[Ian K (N)]

In article <d512c0114c.news@itworkshop.invalid>,
Jess <phantasm_39@hotmail.com> wrote: In message <f0299b114c.druck@druck.freeuk.net> druck <news@druck.freeuk.com> wrote:
On 13 Jul 2003 "Ian K (N)" <news@iank.org.uk> wrote: Although this is useful it doesn't give me enough info on what can actually come out of the port. The Risc PC Technical reference manual isn't detailed enough ether. I'm particularly interested in the support for using TV's as I am trying to drive a 1950's 405 line TV from it via an adaptor. If you know TV signal theory, you can easily make any PAL compatible signal with am MDF.
He wants to make a 405 line signal, not PAL. I would expect that vidc would have no trouble putting out lower sync rates (12kHz???), but is this the case?

The MDF isn't really the problem now. It needs a line frequency of 10125Hz
and a vertical frequency of 25 interlaced frames a sec. so 50 frame fields
a sec. total.
The sync pulses are substantially different to PAL, although I am planing
to mask these and replace them although this requires very precise
information on what is coming out of the Risc PC so I can time everything
correctly. The video signal will also need inverting I am hoping to be
able to do it with a pallet file although I may have to resort to building
some hardware to do this.
If there is someone with an oscilloscope able to take precise readings of
what comes out of the Risc PC, mine isn't up to the job, could they
contact me alternatively if anyone has more info than is in the TRM
concerning the sync pulses

Regards
Ian K


* Inventor of radio controlled knicker elastic!

[Ian Molton]

On Sun, 13 Jul 2003 10:16:05 +0100
"Ian K (N)" <news@iank.org.uk> wrote:
I am trying to drive a 1950's 405 line TV from it via an adaptor.

OOI, *WHY* ?

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[Ian K (N)]

In article <20030715234648.5989c7f0.spyro@f2s.com>,
Ian Molton <spyro@f2s.com> wrote: On Sun, 13 Jul 2003 10:16:05 +0100 "Ian K (N)" <news@iank.org.uk> wrote:
I am trying to drive a 1950's 405 line TV from it via an adaptor.
OOI, *WHY* ?

WHY NOT ? :-)

I have this old Ferguson 943T 405 line telly I would like to use, the
problem is they don't broadcast TV in suitable format anymore. You can
ether get a standards converter which knowone makes anymore and aren't
cheep second hand if you can find one for sale.
Or you can get someone with a standards converter to convert some
programmes form PAL to 405 and record them on a VHS. You can use a
standard VHS player to play these the problem is that modern players
aren't flexible enough to cope with the 405 line standard. Old players
that were brought out in the mid 80's and before will play them but later
ones are more fussy and struggle. My old Ferguson videostar's head has
disintegrated and my other much newer player fails miserably. So it
accrued to me could it be possible to make my Risc PC into a standards
converter as it should be able to generate 405 lines at the appropriate
speed.

Regards
Ian K


* Founder member of the East Fincley On Sea Codswollop Deprecation Society. ;-)

[Martyn Fox]

In article <4c12a43ed4news@iank.org.uk>, Ian K (N) <news@iank.org.uk> wrote:
I am trying to drive a 1950's 405 line TV from it via an adaptor.
OOI, *WHY* ?
WHY NOT ? :-)
I have this old Ferguson 943T 405 line telly I would like to use, the problem is they don't broadcast TV in suitable format anymore.

Some years ago, I visited a tropical wildlife centre housed in part of the
building of the medium-wave transmitting station at Washford, Somerset
(heated by the heat from the transmitters!).

Within the centre was a museum called "Wireless in the West" which included a
collection of old radios, TVs etc. (My kids had their first sight of an
auto-changer record player.)

In a corner of the room was an old TV set with a notice saying that it was
run by the "405-line Preservation Society". Unfortunately, its line
oscillator had lost lock so it was not showing a recognisable picture, but I
recognised the soundtrack as being the 1959 documentary "This is the BBC". I
saw that programme at an impressionable age and maintain that it was largely
responsible for my subsequent career in broadcasting.

ISTR that the notice said that the TV was being fed from a VHS, presumably
modified.

Martyn

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|\/| _ _ -+- _ |_ _ Windsor, Berks. UK
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[Ian K (N)]

In article <5b0c19134c.news@itworkshop.invalid>,
Jess <phantasm_39@hotmail.com> wrote: In message <4c12ccfd28mfox@argonet.co.uk> Martyn Fox <mfox@argonet.co.uk> wrote:
[snip 405 line tv]

ISTR that the notice said that the TV was being fed from a VHS, presumably modified.
I think (old) VHS machine could deal with 405 line video as they stood, but just without the dropout circuitry working.

Some early cheeper VHS machines don't have dropout control at all!

All you need is a modulator with a 45MHz vision and 41.5MHz sound (Channel
1) plugged into the composite video and audio out of the video, and
provided the telly is able to cope with channel 1 frequencies, most are,
it should work.

Regards
Ian K


* "Eere I got an electric twit for christmas!" The Goon Show