C.J.Thornley at coolrose.fsnet.co.uk
Fri Apr 4 00:01:24 BST 2008
How about modifying one of these if you can track one down on eBay or
similar second hand site.
/> Christopher J. Thornley is cjt at coolrose.fsnet.co.uk
\> Home Page :-http://www.coolrose.fsnet.co.uk
From: bbc-micro-bounces+c.j.thornley=coolrose.fsnet.co.uk at lists.cloud9.co.uk
[mailto:bbc-micro-bounces+c.j.thornley=coolrose.fsnet.co.uk at lists.cloud9.co.
uk] On Behalf Of John Kortink
Sent: 03 April 2008 17:00
To: bbc-micro at cloud9.co.uk
Subject: Re: [BBC-Micro] Monitors
On Thu, 03 Apr 2008 15:56:02 +0200, francis at devrx.org wrote:
>>What are you guys using for BBC monitors these days?
>I'm using an Acorn AKF18 (14" multisync monitor supplied with some
>32-bit Acorns), and a cable that I made with resistors on the R,G, and
>B lines and with the BBC's Csync output wired to Hsync on the monitor
>(possibly with a resistor, I can't remember).
I presently use a TV card in a PC, hooked up to the BBC via composite or
S-video (my last low linerate accepting monitor, I think an Eizo 9060S, died
some time ago).
Not too bad, just a bit of colour crawl left (at least on S-video). And
there are pieces of software that can do some useful realtime
post-processing of the analogue video, like thresholding (e.g. DScaler),
which should provide some additional improvement (haven't tried yet).
Suitably wired SCART (with a few resistors) to LCD TV works very well too,
but IMO a TV is not ideal for BBC activity (too big, awkward placing).
>I'm sure the AKF18 won't last forever, so what I'd ideally like is a
>scan-converter type piece of hardware that upscaled to 1280x1024.
>1280x1024 is a multiple of 640x256 and the other beeb resolutions
>there'd be no blurring when displaying this on a 1280x1024 LCD (and
>it'd also look nice on CRTs). Unfortunately I'm not really a hardware
>person so I have no idea how difficult it would be to make such a piece
The main problem is upping the line rate, and the horizontal pixel rate as
well. I suppose somewhat arbitrary scaling would be best, to be able to suit
a number of common native resolutions, not only 1280 x 1024. Perhaps output
letterboxed to widescreen. Etc. De-interlacing is somewhat trivial, since
both frames are from the same source pixels anyway, just displaced in time.
One could probably make do with storing two source lines, one to store a new
source line, the other to replicate a previous one, then swap between the
two every source line. Perhaps some averaging between subsequent output
lines for a smoothing effect.
And, of course, split composite sync into hsync and vsync digitally (and
perhaps draw a separate line to the 6845 pixel clock for accurate pixel
sampling, but this is obviously less than ideal, and a bit of oversampling
will probably suffice).
Ideally, output not (only) to VGA but to DVI (which probably requires a
standard to-DVI chip due to the reasonably high pixel rates involved).
All doable with only a bit of realtively cheap hardware. But in requires a
lot of careful design, and maybe some considerable effort to make it a
little programmable (e.g. being able to switch between unscaled, scaled,
Email : kortink at inter.nl.net
Homepage : http://www.inter.nl.net/users/J.Kortink
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