Frequently Asked Questions


Q. I'm still using a TV set, why should I use a monitor?

A. Monitors give much better pictures than TVs, although top
quality TV sets with SCART inputs can give comparable
results to cheap monitors. However, certain types of monitor
will operate at faster refresh rates than televisions and
that means larger displays with no interlace flicker.


Q. Can I use a PC monitor with an Amiga?

A. Most PC monitors are "SVGA" and operate at a refresh rate
of about 31kHz. The standard Amiga output (say, PAL modes in
640/320 by 256, or 640/320 by 512 interlaced) is 15kHz. This
means an Amiga operating in this mode will not be able to
display a picture. However, Amiga's with the AGA chipset
(A1200, A4000) can open special DoubleScan and Multiscan
screen modes which are very close to 31kHz. Sadly, in most
cases they aren't quite close enough and still the Amiga
won't be able to produce an image on a PC monitor. If you
are offered a PC monitor, try it before you buy it. To be on
the safe side, only with a graphics card can the Amiga
comfortably and reliably drive a PC monitor.


Q. What monitor should I use then?

A. There are a few monitors around which are designed for
the Amiga, such as those produced by MicroVitec. Amiga
Technologies badged some of them before they went under. Not
only will then display standard 15kHz screen modes, but the
DoubleScan and MultiScan modes too. This means you can
display a 640 by 512 Workbench with no interlace flicker.


Q. What is this interlace flicker? How can I stop it?

A. An Amiga operating in a normal PAL video mode can display
a screen of 640 pixels by 256 lines. However a display of
640 by 512 is too much to be produced in one frame of video.
Instead the Amiga takes two attempts, displaying half the
image in alternate frames. The result is a larger display,
but with an annoying flicker. Interlace is acceptable in
some video applications, but it's no good for serious
Workbench work.

To stop the flicker it is necessary to do two things: speed
up the Amiga's video output and display the output on a
suitable monitor: a TV simply isn't up to the task with it's
15kHz refresh rate. You can speed up the Amiga's video if
you have an AGA chipset by using DoubleScan or MultiScan
screen modes, but as discussed these aren't compatible with
most PC monitors and require a dedicated Amiga monitor.
Instead a piece of hardware called a FlickerFixer can be
used. This buffers the two half-frames and then resends them
at a full, uprated speed suitable for display on a PC
monitor. The only FlickerFixer current available is
ScanDoublerII from Power Computing and it requires a Zorro
slot.


Q. How does a graphics card work on the Amiga?

A. The graphics card (for example, Picasso or Cybervision)
fits to a standard Zorro slot. Special driver software
provides extra screen modes: when you alter an application
or Workbench to use these new modes, the video output
appears out of the back of the new card.

As well as the drivers provided with the card, many cards
are supported by a package called "CyberGraphics" or
"CyberGFX". This is a set of drivers which is supported by
many applications, and as long as you have the relevent
drivers for your card you can make use of any software which
support the CyberGFX standard. It's the nearest there is to
a standard for "retargetable graphics".


Q. What are the advantages of using a graphics card on the
Amiga?

A. Graphics cards can open larger displays with more colours
and faster refresh rates than the standard Amiga graphics
chipset. As a result you can use a 256 colour Workbench
screen in 800 by 600 pixels or better, without any flicker
or shimmer. The Workbench display will work extremely
quickly, without using up a lot of Chip RAM.

Unlike the normal Amiga graphics modes which are based on
"bitplanes", graphics cards work in "chunky" screen modes,
which are very suited to moving around large blocks of data
such as Windows. Page Processor/DTP programs and Rendering
packages such as Imagine or Cinema4D will also benefit. It's
also possible to replay animations much quicker: a package
such as Main Actor Professional can play back ANIM files
extremely quickly.

Apple Mac and PC emulators will also work faster with a
graphics card because they too are used to Chunky screen
modes.

Although HAM8 mode can display many colours, graphics cards
can display true 24 bit images. The art programs TV Paint
and Photogenics can make use of the new graphics modes to
display thousands or millions of colours extremely quickly.
Your graphics will never look so sharp, bright or colourful.


Q. Are there any disadvantages to using a graphics card?

A. Yes. For a start you need a suitable Amiga as all
graphics cards require Zorro slots. Then you'll need a
decent monitor: it would be a waste of time attempting to
use a graphics card with a TV or 15kHz monitor. You need a
PC style SVGA monitor, and the bigger the better. If you
want resolutions larger than 800 by 600 you'll need a 17"
monitor, and that's another £500.

When you do get your graphics card system connected to the
new monitor, you'll find that not all programs will work
properly. Most applications will work perfectly, but hardly
any games will run and you'll need to resort to your old
monitor or TV to see them. This is because for speed reasons
games don't request screen modes or perform graphics tasks
through the operating system: and that means they can't be
re-directed to the graphics card.

The Amiga's standard bitplane graphics are much more
video-friendly than the output from graphics cards. Smooth
scrolling, genlocking and high-quality video titling is
still best left to the standard Amiga output. DTV fans will
gain little from a graphics card.


Q. Do all graphics cards really require Zorro slots? I have
an A1200, am I stuck?

A. One soluton is to buy a Tower Case adaptor which includes
Zorro slots, but that is an expensive route to take. A new
module called Grafitti will apparently appeal to the
Zorro-less or budget minded. It connects to the standard
monitor output and provides special chunky graphics modes.
This can speed up certain applications a great deal. More
details when the review model arrives.