Amiga Collections: MegaDisc/MegaDisc 02 (1987)(MegaDisc Digital Publishing)(AU)[WB].zip/MegaDisc 02 (1987)(MegaDisc Digital Publishing)(AU)[WB].adf/ARTICLES/Hardware

Text File | 1987-04-21 | 5KB | 96 lines

                           ABOUT YOUR HARDWARE
                           ===================
                             ABOUT MONITORS
                             ==============


   The 1080 monitor that most of us are using is a pretty serviceable
device and seems to have only the one drawback - the flicker that occurs
in "Interlace" mode. Some have probably played around with it on Deluxe
Paint (by entering    > dpaint hi   at boot-up) or, if you have the 1.2
software (see article this issue), you may have used Preferences to set
the screen to Interlace. And most have probably decided that it's a bit
too irritating and gone back to the normal medium-resolution 640*200
screen. However, it is useful in Word Processors such as Scribble! or in
Communications programs, to use hi-res so as to see more text on the
screen at once, and thereby reduce scrolling. It's also very useful for
doing a lot of icon-swapping between two or three discs at once.

REDUCING FLICKER

   A couple of useful tricks - firstly, as many know, you can fiddle
with the colours on the Preferences screen to find a combination which
doesn't contrast too strongly  yet maintains good legibility. Just
experiment by selecting colour combinations with the slider, and clicking
on the front/back gadgets at the top right of the Preferences window to
see the effect on your current screen - have your WP or ED in the CLI
running.  Secondly, just wear sunglasses - try it, it really does cut
down on flicker. Thirdly, you can buy special screens to clip over
the front of your screen which supposedly reduce flicker substantially.
And you can run the program SETLACE from FISH DISK 9, or its recent update
LACETOGL ( a lot smaller than its predecessor at only 248 bytes), which I
believe actually fills up those tiny little black lines across your screen,
by scanning the screen twice with the same scan (see explanation Hints&Tips),
giving a more stable and unlined screen display. Another source of
variation in your screen display is possible by playing with the knobs on
the back of your monitor, if it's an Amiga 1080 or similar. You can use
the Vertical Height control to squeeze down the screen to reduce the space
between scan lines, and with the three controls available you can make
all kinds of adjustments - experiment a little. These controls are found
at the back left bottom corner of your monitor as you look at the screen.

 So if you're using the 1.2 system discs, with LaceTogL and Interlace
running, with the right colour combinations, and with a program which can
handle full re-sizing of windows, you can get twice as much onscreen with
minimum irritation. Certainly, it improves SCRIBBLE! and the CLI
environment, and if you're doing a lot onscreen at the same time you've
got the space for it all.

REASON FOR FLICKER

   Your monitor's screen is coated on the inside with three types of
phosphor arranged in tiny triples of vertical red, green and blue bars,
hence " RGB" monitor. These different phosphors have different
characteristics such as Colour (of course), Fade time and brightness.
So in constructing the monitor these variable phosphors must be matched
as closely as possible, and this match can't be exact.
   The 1080 has been made for non-interlaced displays, which means
that the electron beam which strikes and excites the phosphors is designed
to do so every 1/60th of a second, and the phosphors only have to glow for
that time. Thus the phosphors are Short Persistence type, which are
cheaper at present.
   When the interlace is turned on the screen has 400 horizontal
scan lines rather than the normal 200. Due to historical video standards
the electron beam can only scan 200 lines at a time, so the way around
the problem was to scan every second line in one pass of the screen, and
then scan the ones between in the next pass. So the first pass excites
the phosphors on every second line, the second pass excites the ones
in between, and ideally the first set of phosphors glow long enough to
merge evenly with the glowing phosphors of the next pass, to create a
whole-screen image.
   The brighter the phosphor, the more quickly it fades. If it fades
before 1/30th of a second has passed you get the effect of brightness
and dimness on alternate lines on the screen, and as this is a dynamic
process the effect is that flicker. So you can see that if you choose
dim colours from your Preferences, they will seem to fade more slowly,
thus merging better and thus reducing flicker. Alternatively, you can
buy a High-Persistence Monitor, in which the more expensive phosphors
glow for a little longer and so merge better in the double scan. A
side-effect of this can be that if you are moving images around the screen
as in an animation, you'll probably have a glowing "trail" left behind.

   It's interesting to note that monitors depend on the tricks our
eyes play to work properly. What's actually happening on screen is that
the electron beam is only at one spot at any instant - so anyone with
perfect vision would be seeing a black screen. However, our retinas
keep an image for a while, which allows us to form a complete merged
picture of the screen, and a good thing too. But what is this thing called
Reality?


END OF HARDWARE
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