[F040] NOVA and LCD display

From: Oliver Skelton <skelton_at_fuchinobe.skk.slb.com>
Date: Mon, 27 Nov 2000 13:31:34 +0900

(Sorry if you get this twice. I tried the old list first but it doesn't
seem alive - and sorry for not being 100% on topic but I know this list
contains the people who probably knows these topics well)

After my beloved Idec Visionmaster died I got seduced into buying a
'cheap' 15" LCD display.
(An Ota-15a, to be exact).
This is broadly equivalent to a 17" CRT. It supports a 1024x768 pixel 24
bit display. In fact it is quite glorious showing this resolution from
the PC, but rather lets down when running games or at the DOS boot
screen when the display is too far to the left (beyond adjustment... not
enough blanking time from the graphics card?) and there are horizontal
streaks of varying brightness caused by the content of the picture at
the left edge of the display. Also when showing lower resolutions there
is the usual LCD problem of scaling causing some blurring of text.
Anyway, 1024x768 is what I bought it for.

Now naturally I want to get it running with my Falcon/AB040/NOVA combi.
My problem is I cannot get the NOVA to display a 1024x768
resolution.When I configure such a resolution with the VMG (Video mode
generator) program and click to test it it gives me garbled screen
(black and grey rectangles) and the Falcon seems to need a reboot. I am
interested if any of the knowledgeable bods here could give any
Also if they can verify my surmises about LCD displays which are...

1. When playing with video settings there isn't the same risk of
damaging an LCD display as there is with a CRT because it presumably
doesn't derive critical voltages from the horizontal and vertical

2. As there is no discernable flicker (the leds are illuminated by a
fluorescent tube, not by rapidfire refresh from a electron beam) then
there is no need to go for high refresh rates. A lower refresh rate will
reduce the load on the graphics card and possibly system and permit
higher resolutions?

3. But... (at least for DVD playback from PC) it is desireable for the
refresh rate to be a multiple of a movie frame rate. i.e. 60Hz for NTSC
and 50 or 75Hz for PAL?

4. As there is no electron beam to have to be steered back to the
beginning of each line or back to the top of the screen then the
blanking times can be reduced?

For the record, the display is specced at:
24-61kHz, 56-75Hz
I suspect it may not be a true multisynch. There is a table of
resolutions e.g.:
NEC PC9801 640x400 24.83 kHz 56.42 Hz 21.05 MHz -/- polarity
VESE-768-75Hz 1024x768 60.023kHz 75.029Hz 78.75 MHz +/+ polarity
This presumably covers all the standard resolutions. There is also a
note to say part of the screen is not visible in the following
resolutions: 640x350, 640x400, 720x400

Received on ma. nov. 27 2000 - 11:01:04 CET

This archive was generated by hypermail 2.3.0 : ti. nov. 03 2015 - 20:07:54 CET