From: John_Shepardson.esh@qmail.slac.stanford.edu (John Shepardson)
Subject: Re: Quadra 700 questions..
Followup-To: comp.sys.mac.hardware
Organization: Stanford Linear Accelerator
Distribution: na
Date: Wed, 27 Jan 1993 21:47:52 GMT

In article <1993Jan27.182107.8777@ra.oc.com>, wier@merlin.etsu.edu (Dr.
Robert R. Wier) wrote:

> When you look at the memory slots, you'll see some sockets
> in addition to the standard SIMM slots which are labeled
> VIDEO SRAM - since the Quadra normally comes with 8 bit color/
> b&w capability, what does filling these memory slots give you?
> Increased speed? 24 bit color? 


Here is an old posting by the original Quadra video engineer:
Hey Dale, think you might update us for the 950 and on?

From: Dale_Adams@gateway.qm.apple.com (Dale Adams)
Newsgroups: comp.sys.mac.hardware
Subject: Mac Quadra Video Explained, Part 3
Date: 25 Nov 91 17:02:16 GMT
Organization: Apple Computer, Inc.,  Cupertino, CA

Macintosh Quadra Built-In Video, Part 3:  VRAM Configurations

This is the third in a series of articles which describes the capabilities 
of the built-in video of the Quadra 700 and 900.

The Quadra frame buffer supports a variety of pixel depths, from 1 to 32 
bits per pixel (bpp).  The supported pixel depths (1, 2, 4, 8, or 32 bpp) 
depend on the display resolution and the amount of VRAM in the Quadra.  
The fully expanded capability of both Quadras is the same, i.e., both the 
900 and 700 can be expanded to 2 MB of VRAM.  However, note that 512K of 
VRAM is the minimum configuration for the Quadra 700 whereas it is 1MB of 
VRAM for the Quadra 900 (this is the amount of VRAM soldered on the 
motherboard).  The Quadra 700 has 6 VRAM expansion slots, while the 900 
has only 4.  Also note that only 0.5 MB, 1 MB, and 2 MB configurations are 
supported (i.e., 1.5 MB is not supported).

The Quadra 700 and 900 can be expanded using 256K (i.e., 128K x 16) 100 nS 
VRAM SIMMs.  These are the same as the VRAM SIMM shipped in the base 
configuration of the Macintosh LC, or the VRAM SIMMs used to expand an 
Apple 4*8 video card to an 8*24 card.  Note that the 512K VRAM SIMMs used 
to upgrade the Mac LC will _not_ work in a Quadra.  (The 256K SIMMs 
removed from an LC when performing a VRAM upgrade will work, however.  All 
those old 256K VRAM SIMMs laying around from upgraded LCs can be used to 
upgrade Quadra 700s and 900s!)  The DRAM SIMMs used to upgrade an 8*24GC 
video card will also not work.

The following chart lists the Quadra 700 & 900 built-in video's maximum 
pixel depth supported depending upon the VRAM configuration:
 
Display size                        512K VRAM     1MB VRAM     2MB VRAM
                                    ---------     --------     --------
12-inch landscape
384 x 512
(such as 12" RGB)                    8 bpp         32 bpp       32 bpp
 
12-inch Monochrome
640 x 480                            8 bpp          8 bpp        8 bpp
 
13-inch RGB & VGA
640 x 480                            8 bpp          8 bpp       32 bpp
 
SVGA
800 x 600                            8 bpp          8 bpp       32 bpp
 
15-inch Portrait (b/w)
640 x 870                            4 bpp          8 bpp        8 bpp
 
16" Color,
832 x 624                            8 bpp          8 bpp       32 bpp
 
2-Page Display (b/w)
1152 x 870                           4 bpp          8 bpp        8 bpp
 
21" Color
1152 x 870                           4 bpp          8 bpp        8 bpp
 
PAL without convolution
underscan-640x480                     8 bpp        8 bpp        32 bpp*
overscan-768x576                      8 bpp        8 bpp        32 bpp*
 
PAL with convolution
underscan-640x480                      n.a.        8 bpp         8 bpp
overscan-768x576                       n.a.        8 bpp         8 bpp
 
NTSC without convolution
underscan-512x384                     8 bpp        8 bpp        32 bpp
overscan- 640x480                     8 bpp        8 bpp        32 bpp
 
NTSC with convolution
underscan-512x384                     n.a          8 bpp         8 bpp
overscan- 640x480                     n.s          8 bpp         8 bpp
 
*Note there are two ways to cable a PAL monitor to a Quadra; only by using 
the proper extended sense code are you able to achieve 32 bits per pixel.
For details, refer to the previous article on Quadra video sense pinouts.


*********************************************************************
* Dale Adams             *   Opinions expressed are not necessarily *
* Apple Computer, Inc.   *   those of my employer.                  *
*********************************************************************