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80 column card for C64 [message #74085] Sun, 26 May 2013 20:53 Go to next message
wg is currently offline  wg
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Registered: May 2013
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Message-ID: <163@aluxp.UUCP>
Date: Mon, 8-Oct-84 20:54:39 EDT
Article-I.D.: aluxp.163
Posted: Mon Oct  8 20:54:39 1984
Date-Received: Tue, 9-Oct-84 04:05:59 EDT
Distribution: net
Organization: AT&T Bell Laboratories, Allentown, PA
Lines: 9


I am considering purchasing an 80 column card for my C64.  Are there any
recommendations from the net, either current or past?  A particular question
I would like answered is the quality of display when used on a normal TV.
Thanks in advance!

Bill Gieske
AT&T-BL
AL X5137
Re: 80 column card for C64 [message #74097 is a reply to message #74085] Sun, 26 May 2013 20:53 Go to previous message
doug is currently offline  doug
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Message-ID: <176@terak.UUCP>
Date: Mon, 15-Oct-84 16:15:29 EDT
Article-I.D.: terak.176
Posted: Mon Oct 15 16:15:29 1984
Date-Received: Thu, 18-Oct-84 06:44:26 EDT
References: <163@aluxp.UUCP>
Distribution: net
Organization: Terak Corporation, Scottsdale, AZ, USA
Lines: 32

> 
> I am considering purchasing an 80 column card for my C64.  Are there any
> recommendations from the net, either current or past?  A particular question
> I would like answered is the quality of display when used on a normal TV.
> Thanks in advance!
> 

Forget about using a normal TV for 80-column work.  Televisions have
a video bandwidth of 4.2 MHz (3.8 to 4.5).  This means that the TV can
paint 4.2 million different dots per second.  Since each line will be
drawn in 1/15750 of a second, there can be 267 different dots per line.
This figure includes the dots in the border on both the left and right
sides, plus the "retrace" when the beam "carriage returns" from the
right edge of one line back to the left edge of the next.

As you can see, the normal 320 dots-per-line that the C-64 uses is
beyond the capability of a TV, and this shows up as a "smearing" or
lack of sharpness in the lettering.  The C-64 makes each letter 8
dots wide, giving 40 letters across the screen.  An 80-column card
could have letters as narrow as 6 dots and still have good readability,
but this would require 480 dots per line.  There is one word processing
package being advertised which uses the standard 320 dots and tries
to get by with 4-dot wide letters.  That's just too few dots to
be able to distinguish the different letters, and the smearing
just finishes the job.

Using a standard monitor won't help much, since the C-64 is still
generating a signal which is limited to TV standards.  You would
need an 80-column card which has its own "wideband" output which
you could then connect to a wideband monitor.

        Doug Pardee -- Terak Corp. -- ...!noao!terak!doug
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