riscy
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Re: X-Listprocessor-Version

To: riscy@sunsite.unc.edu
Subject: Re: X-Listprocessor-Version
From: kent@tifsim.pac.sc.ti.com (Russell Kent)
Date: Fri, 19 Nov 93 7:00:41 CST
In-reply-to: <9311190922.AA19333@dutecai.et.tudelft.nl>; from "Rogier Wolff" at Nov 19, 93 4:24 am
Roger Wolff (wolff@liberator.et.tudelft.nl aka WOLFF@DUTECAI.ET.TUDELFT.NL :-)
writes:

> Jeeez.  If you want to advertize "High End" then you need to support more 
> than 1024x768 at 24 bits per pixel. To me "High End" is at least 1280x1024,
> even at 24 bits per pixel. You don't even need more than 4Mb RAM to 
> pull this off....
Hey, I said I was sorry for the commercial hype-speak ;-)


> According to SGS Thompson info I have at 1600x1280@70Hz, you need a video
> bandwidth of 1.3 * 1600 * 1280 * 70 = 186Mhz. With three bytes per pixel
> you need 560 Mb per second of video data. At 8 bytes per transfer you
> get a 70Mhz transfer rate of video data. This is slightly tricky, but
> not unusual for high end systems. 
>                                                 Roger.

Umm, not quite.  The TVP3020 does 24-bit video for lower resolutions only.
(Aside: just what constitutes "lower resolution" here is unclear, but the
news article said less than 1600x1280.  It may be that it does support
24-bit true color at 1280x1024.)

At 1600x1280 it does 16 bits/pixel, so:

    1.3 * 1600x1280 * 70(MHz) = 186Mhz
    *2* bytes per pixel       = 372MB / sec
    divided by 8 bytes per bus transfer = 47 Mhz transfer frequency

which, being smaller, I would expect it to be somewhat easier to manage
than a 70Mhz transfer frequency.  Of course, I'm still just a software
weenie (with a math degree ;-) and don't understand what this really means...

Russell Kent
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