Abstract of INFO-MAC archived Text file
   'info/hdwr/centris-quadra-800-video.txt'
  Uploaded 04/04/1993   14575 bytes

Date: Tue, 30 Mar 93 09:03:17 EST 
From: vita@sunny.dab.ge.com (Mark Vita)
Subject: Centris / Quadra 800 video report 

Here is a very informative report on the built-in video capabilities of the
Apple's new Centris 610/650 and Quadra 800 machines.  The report was
written by Dale Adams, the designer of the video hardware on those
machines.  It includes a complete description of the available resolutions
and bit depths, the types of monitors supported, and the video connector
pinouts (including the sense pin configurations necessary to enable the
various display types).

Mark Vita                                  vita@sunny.dab.ge.com
GE Simulation and Control Systems
Daytona Beach, FL


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Built-In Video on the Macintosh Centris 610/650 and Quadra 800

There will probably be a number of questions which arise concerning the
built-in video capabilities of the new Macintosh Centris 610 and 650, and the
Quadra 800.  In anticipation of these questions, here is an article (similar to
that which I posted for the earlier Quadra machines) which provides an
description of these video capabilities.  This article discusses a few general
video topics, details how to wire the video connector sense pins to access all
the supported video modes of these machines, and describes the memory
configurations necessary to support each of the video modes at specific pixel
depths.  (I am the designer of the video hardware for the Quadra
700/900/950/800 and the Centris 610/650, you can be reasonably sure this
information is accurate.)


General Video Design Philosophy
--------------------------------------
The video hardware design of the Centris 610/650 and the Quadra 800 is highly
derivative from the earlier Quadra machines.  However, one of the main goals of
these CPUs (and perhaps the #1 goal) was to reduce the cost of the machines
relative to the Quadra 700 and 950, while still providing the same (or better!)
performance.  While it was not possible to significantly reduce cost while
maintaining the exact feature set of the earlier Quadras, most of the Quadra
video features were carried through to the Centris 610/650 and Quadra 800.  The
main exceptions are support for Apple convolution (flicker reduction) for NTSC
and PAL, and support for 24 bits per pixel (bpp).

The video hardware for all three CPUs, the Centris 610 (C610), Centris 650
(C650) and Quadra 800 (Q800), is virtually identical.  The only exception is
that the C610 only requires 100 ns VRAM, while the C650 and Q800 require 80 ns
VRAM.