Re: Apple Monitor Models that works with IIgs

[mjmahon@aol.com (Michael J. Mahon)]

Rubywand wrote:

>Mark Frischknecht writes ...
>> 
> ....
>> 
>> The problem is the Apple IIgs uses a 15khz Horizontal Refresh and
>> Nearly All modern monitors use a 31khz Horizontal Refresh rate. To
>> hook up a modern monitor to a iigs you need to wire up a iigs to vga
>> adapter and double the horizontal scanrate which most products that do
>> that are about 100 - 200 dollars
>> Or you can purchase a early multisync monitor like the NEC Multisync
>> 3D. IT MUST support a 15khz Horizontal Sync. What I use is a XRGB-1
>> Upscan Converter. The model that is being sold now is a XRGB-2 Plus
>> Upscan Converter.
>
>     Have heard of scan converters and wondered how well they work. Does the
>display look the same as with a regular IIgs monitor? 

There are two kinds of scan converters:  expensive professional models
and (relatively) inexpensive consumer models.

The professional models are hundreds of dollars, and use oversampling
to achieve good NTSC-rate RGB or component video to RGB VGA
standards.

The consumer models are typically $80-$180, and use target VGA
dot rate sampling of a composite or an S-video input.  The result is
that fine details in the incoming NTSC-rate signal "twinkle" on the
VGA display or show "jaggies" because of the lack of lock between
the converter's sampling clock and the computer's dot clock.

So there are two fundamental problems with "consumer grade"
converters:  no RGB input for high bandwidth, and no oversampling
or sampling phase lock.

The result is, in my opinion, much worse than a good composite
monitor when working from composite video in.

>     How much hassle is it to hook up the converter? Is there any info
>available on the connections?

The hookup is easy--the results are poor.

There is no fundamental reason why a good one cannot be built,
but I haven't seen one yet.  Part of the problem is that the volume
market for such converters is for video game enthusiasts, and there
aren't (yet?) a lot of people who want to convert high resolution
component video to VGA.  (And should that happen, if the most
common inputs are continuous-tone imagery, as opposed to
fine-line fonts and graphics, there may be no requirement to
oversample or phase lock to the incoming dot clock.) 

Google for scan converters and you'll see a bunch.

-michael

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