Info-Mac 1993 May/Info-Mac_II_May_1993.to_.sit/Info-Mac II (May 1993).toast/Technical/Quadra Video Notes.txt

Internet Message Format | 1992-08-29 | 24KB

From: [e-mail] (Mel Martinez x8378)
Subject: [*]Quadra video overview (tech)
Date: Tue, 14 Jul 92 15:20:11 EDT

Due to the number of private requests I keep getting for info on the quadra
videos, I can't get any of my own work done!  :)

I am forwarding the following document to the archives.  It describes the
quadra internal video very well and should be very useful to many quadra
owners.  It is written by the designer of the quadra video himself, Dale Adams,
and was originally posted in comp.sys.mac.hardware (I think).

Please archive as info-mac/tech/quadra-video-notes.txt

Mel Martinez
The Johns Hopkins University
Dept. of Physics




-- snip here --

> From: [e-mail] (Dale Adams)
> Newsgroups: comp.sys.mac.hardware
> Subject: Mac Quadra Video Explained, Part 1
> Date: 25 Nov 91 16:39:34 GMT
> Organization: Apple Computer, Inc.,  Cupertino, CA

Macintosh Quadra Built-In Video, Part 1: Video Architecture

There have been quite a few questions in this (and other) news groups
concerning the built-in video capabilities of the new Macintosh Quadra 700
and 900.  In response to these questions, here is the first of three
articles which provide an in-depth (and accurate!) description of the
Quadra video capabilities.  This first article discusses a number of
general Quadra video topics, the second details how to wire the video
connector sense pins to access all the Quadra's supported video modes, and
the third describes the memory configurations necessary to support each of
the video modes at specific pixel depths.  And by the way, I am the
designer of the video hardware for both Mac Quadras, so this information
is accurate.

The Quadras were designed with a flexible video hardware section in order
to support a wide variety of displays.  Since the purchaser of one of
these CPUs is paying for a frame buffer on the motherboard (whether (s)he
wants it or not), and since the Quadras were designed to be high
performance machines, the frame buffer was designed to be both very
flexible (to support most displays a user may want to use) and to be
relatively high performance (to match the computer's capabilities).

Obviously every display made by every 3rd party monitor vendor can't be
supported by the onboard video, but the Quadras do support a much wider
range of displays at a higher level of performance than any previous
Macintosh.  The Quadra 700 and 900 support pixel depths ranging from 1 to
32 bits per pixel (bpp), Apple displays ranging from the 512 x 384 12-inch
color monitor through the 1152 x 870 21-inch color monitor, pixel clocks
ranging from 12 to 100 MHz, and a variety of industry standards such as
VGA, SVGA, NTSC, and PAL.  The Mac Quadra video port produces RS-343 RGB,
and also provides horizontal, vertical and composite sync outputs.
Composite or S-video output is not provided, but can be accomplished by
use of an external RGB-to-composite encoder.  The Quadra 700 and 900 also
support Apple convolution for flicker-reduction on interlaced displays
(i.e., NTSC and PAL) at up to 8 bpp.  The Mac Quadras automatically detect
the type of display attached to the video connector via 3 'sense' pins on
the video connector.  Depending on the wiring of these 3 pins, software in
ROM configures the video hardware for one the supported display types.  (A
full description of sense pin wiring and supported display types is in the
2nd article.)

The Quadra 700/900 provide the highest built-in video performance of any
Macintosh CPU to date.  In a (very) simplified graphics model, we could
say that performance depends on two main factors: processor horsepower and
the bandwidth the processor has into frame  buffer memory.   These
machines already have a fast processor - the 68040 - which runs standard
32-bit QuickDraw.  To provide high bandwidth into frame buffer memory,
dedicated video RAM (VRAM) was used for the frame buffer, and that VRAM
was placed directly on the 68040 processor's local bus.  This provides the
68040 the same access time into frame buffer memory that it has into main
system RAM.  (Transfer rates can exceed 40 MBytes/sec.)  In addition,
memory options such as fast page mode are supported, which can improve
graphics performance for operations such as scrolling,
offscreen-to-onscreen pixmap transfers, etc.

In a number of cases the design was optimized for high performance over
low cost.  A good example of this is 32 bpp operation on Apple's standard
13-inch RGB monitor at 640 x 480 resolution (and this also applies to VGA
and NTSC), which is probably the most common color monitor in use on the
Macintosh.  The actual number of memory bytes needed to support 24 bpp is
640 x 480 x 3 = 921,600.  This would seem to fit within 1 MByte of memory
(as is the case with the Apple 8*24 video card), but the Quadras actually
require 2 MBytes of VRAM for this mode.  The 8*24 card supports 24 bpp at
640 x 480 by using a storage mode called 'chunky planar' to fully utilize
all its 1 MByte of VRAM.  However, this results in having to perform 3
separate memory accesses for each 24-bit pixel read from or written to the
frame buffer.  (This is done in hardware so software only performs a
single read or write.)  On a NuBus video card, this inefficiency is
partially masked by the synchronization delays which occur at the
processor-bus/NuBus interface.  However, when frame buffer memory is
placed directly on the processor bus, this approach results in a nearly 3X
performance degradation.  This was judged unacceptable for the Quadras.
Each 24-bit pixel occupies one longword (4-bytes) in VRAM, so the Quadras
actually provide 32 bpp for the 640 x 480 resolution.  This pushes the
memory requirement for this mode over the 1 MByte boundary (640 x 480 x 4
= 1,228,800 bytes).  Performance is improved still more by another frame
buffer architectural feature.  Frame buffer memory in the Quadras is
organized into 4 'banks' of 512 KBytes per bank.  As mentioned earlier,
Quadra VRAM can operate in fast page mode.  In addition, each bank of VRAM
operates in fast page mode independently of the other 3 banks.  This
causes the number of in-page 'hits' to increase, and thus improves the
effective bandwidth into the frame buffer.  Also, at 32 bpp, 640 x 480
resolution, each row is set to 4096 bytes, or 1024 32-bit pixels.  Each
successive row is assigned to a different VRAM bank (modulo 4, of course).
 This memory organization improves performance during certain commonly
performed graphics operations such as vertical scrolling.

In any design there are a number of tradeoffs to be made, and this is
certainly true for the frame buffer in the Mac Quadra machines.  While the
video does operate at 32 bpp on up to 16-inch displays, it does not
support 21-inch displays at this pixel depth since this would have
significantly raised the cost of the motherboard.  (Memory capacity and
bus bandwidths would essentially have to double, and this would be
expensive.)  It does support NTSC and PAL timing, but does not provide a
composite video output.  While it is much faster than any non-accelerated
video card, there are accelerated video cards that are faster (and much
more expensive, too, by the way).  A separate graphics processor was not
added primarily for cost reasons.  However, a graphics processor such as
the 29000 RISC chip on the 8*24GC card can only speed up the graphics
operations that it was designed to know about.  If an application program
bypasses QuickDraw (which is what most Mac graphics accelerators are
designed to speed up), a graphics accelerator will not improve
performance, and can actually cause a performance degradation.

Overall, the Macintosh Quadra video provides a reasonable compromise of
cost, performance, and features, which provides the video needed by the
majority of Macintosh users at a reasonable price.

The second article will detail the displays supported by the Quadra's
onboard video, and will explain how to configure the sense pins for each
of these configurations.


*********************************************************************
* Dale Adams             *   Opinions expressed are not necessarily *
* Apple Computer, Inc.   *   those of my employer.                  *
*********************************************************************
--
 ...Doug Bitting... || "But the wisdom that comes from heaven is first
                    ||  of all pure; then peace loving, considerate,
[e-mail] ||  submissive, full of mercy, and good fruit,
[e-mail]  ||  impartial and sincere."  -- James 3:17
--
--
Minnie Mouse is a slow maze learner.


Article 15039 of comp.sys.mac.hardware:
Path: boulder!agate!dog.ee.lbl.gov!network.ucsd.edu!swrinde!mips!spool.mu.edu!yale.edu!cs.yale.edu!bitting-douglas
From: [e-mail] (Douglas Bitting)
Newsgroups: comp.sys.mac.hardware
Subject: REPOST: Mac Quadra Video Explained, Part 2/3
Summary: (Was: Re: Quadra + VGA monitor?)
Message-ID: <[e-mail]>
Date: 28 Feb 92 15:36:14 GMT
Sender: [e-mail] (Usenet News)
Organization: You gotta be kidding me!
Lines: 223
Nntp-Posting-Host: zoo-gw.cs.yale.edu


Several people have made allusions to the posts from November 1991 by
Dale Adams, the designer of the Quadra's internal video.  As luck
would have it, I did save these out of curiosity.  So, here is a
repost.  It is in 3 parts.  This is part 2.  This is reposted without
permission; I hope Dale doesn't mind.

--Doug

-- snip here --

> From: [e-mail] (Dale Adams)
> Newsgroups: comp.sys.mac.hardware
> Subject: Mac Quadra Video Explained, Part 2 (long)
> Date: 25 Nov 91 16:58:24 GMT
> Organization: Apple Computer, Inc.,  Cupertino, CA

Macintosh Quadra Built-In Video, Part 2:  Supported Display Configurations

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

The Quadra frame buffer determines what type of display is attached to the
video connector by examining the state of 3 sense line pins.  The
following chart details how these three pins must be wired for each of the
supported display types.  For each supported display, the screen
resolution (horiz. pixels  X  vertical pixels), dot clock frequency, and
the vertical and horizontal scan rates are listed.

Basically, the Quadra 700 & 900 support any display, whether from Apple or
from another vendor, that meets one of the following specifications:

STANDARD SENSE CODES:

                    Sense pins    Hor x Vert     Dot      Vert     Horiz
Display              10  7   4      Pixels      Clock    Refrsh   Refrsh
-----------         -----------   ----------    -----    ------   ------

Apple 21S Color      0   0   0    1152 x 870     100       75      68.7

Apple Portrait       0   0   1     640 x 870    57.2832    75      68.9

12" Apple RGB        0   1   0     512 x 384    15.6672   60.15   24.48

Apple 2-Page Mono.   0   1   1    1152 x 870     100       75      68.7

NTSC                 1   0   0  underscan-512x384 12.2727  59.94   15.7
                     1   0   0  overscan- 640x480 12.2727  59.94   15.7
(To produce a color NTSC signal, a RGB-to-NTSC converter is required.)

12" AppleMonochrome  1   1   0     640 x 480     30.24     66.7    35.0

13" Apple RGB        1   1   0     640 x 480     30.24     66.7    35.0

Extended sense codes will be examined if the following sense code is
detected:
                     1   1   1


NOTE 1 on above monitors: A sense pin value of 0 means that the pin should
be grounded to the C&VSYNC.GND signal; a value of 1 means do not connect
the pin.

NOTE 2 on above monitors: sense pins 4, 7, and 10 are referred to as
SENSE0, SENSE1, and SENSE2 in pinout tables for the video connectors.

NOTE 3: The terms 'underscan' and 'overscan' are used to describe the
active video resolution for NTSC and PAL modes.  Underscan means that the
active video area appears in a rectangle centered on the screen with a
black surrounding area.  This ensures that the entire active video area
always is displayed on all monitors.  Overscan utilizes the entire
possible video area for NTSC or PAL.  However, most monitors or
televisions will cause some of this video to be lost beyond the edges of
the display, so the entire image will not be seen.



EXTENDED SENSE CODES:

NOTE for extended sense codes: A sense pin pair value of 0 means those
pins should be tied together (as opposed to grounding the pins to pin 11);
a value of 1 means do not connect the pins.  Do _not_ wire any of these
pins to ground.

                   Sense pins    Hor x Vert      Dot      Vert     Horiz
Display           4-10 10-7 7-4    Pixels       Clock    Refrsh   Refrsh
-----------       -------------   ----------    -----    ------   ------

16" Color,
(i.e., E-Machines)  0   1    1     832 x 624    57.2832    75      49.7

PAL
PAL has two wiring options, using the extended sense pin configuration.
To produce a color PAL signal, an RGB-to-PAL converter is required.

PAL Option 1        0    0    0  underscan-640x480 14.75   50     15.625
                                 overscan-768x576  14.75   50     15.625
Note: This configuration does not presently doesn't support 24 bits per
pixel.

PAL Option 2        1    1    0  underscan-640x480 14.75   50     15.625
                                 overscan-768x576  14.75   50     15.625
Note: This sense code also requires a diode between sense pins 10 & 7,
with anode towards pin 7, cathode towards pin 10.


VGA                 1    0    1    640 x 480     25.175    59.95   31.47

SVGA                1    0    1    800 x 600       36        56    35.16
To enable SVGA, after configuring and connecting the monitor for VGA, open
the Monitors control panel and select Options.  Choose Super VGA from the
dialog and reboot your system.

No external monitor (video halted)
                    1    1    1



Here are the Macintosh Quadra video connector pinouts:

Pin    Signal          Description
-----  -----------     ----------------------------------------
1      RED.GND         Red Video Ground
2      RED.VID         Red Video
3      CYSNC~          Composite Sync
4      MON.ID1         Monitor ID, Bit 1 (also known as SENSE0)
5      GRN.VID         Green Video
6      GRN.GND         Green Video Ground
7      MON.ID2         Monitor ID, Bit 2 (also known as SENSE1)
8      nc              (no connection)
9      BLU.VID         Blue Video
10     MON.ID3         Monitor ID, Bit 3 (also known as SENSE2)
11     C&VSYNC.GND     CSYNC & VSYNC Ground
12     VSYNC~          Vertical Sync
13     BLU.GND         Blue Video Ground
14     HSYNC.GND       HSYNC Ground
15     HSYNC~          Horizontal Sync
Shell  CHASSIS.GND     Chassis Ground



If your monitor is a VGA type, you can try the following cable pinouts.

Macintosh Quadra                         VGA Connector
DB-15
-------------                           --------------

2  ------------------- Red Video ------------ 1
1  ------------------- Red Ground ----------- 6
9  ------------------- Blue Video ----------- 3
13 ------------------- Blue Ground ---------- 8
5  ------------------- Green Video ---------- 2
6  ------------------- Green Ground --------- 7
15 ------------------- Hsync ---------------- 13
12 ------------------- Vsync ---------------- 14
14 ------------------- Sync Ground ---------- 10
10 ------------------|
7  ------------------| Connect 7 and 10 so the sense pin ID will equal VGA

There are a few issues to keep in mind with VGA monitors:

 * VGA monitors will vary depending on the vendor.  Check with the vendor
   about Macintosh Quadra compatibility before buying, or better yet,
   actually try the monitor with a Quadra to see if it works and if the
   quality is acceptable.

 * Vendors have different image quality specifications.  There may be
   significant differences between Apple monitors and the wide range of
   VGA monitors.  Do a side-by-side comparison of the monitors you are
   considering before buying.

 * Many third party cable vendors have off-the-shelf cables that should
   work.



Most NTSC devices use an RCA-type phono-connector and the following
diagram uses that as a reference point.  A cable wired as follows may
allow many different brands of NTSC monitors to work on a Macintosh
Quadra.  I would advise you to test the monitor on a Macintosh Quadra
prior to purchase to see if it meets your expectations.

Adjust the phono-connector side to whatever type of connector is used
(RCA, BNC, etc.).  "Tip" is the pin in the center of the connector (the
signal); the sleeve is flange around the outer edges of the connector (the
chassis ground).

   Card Connector                     RCA-Type Phono-Connector
   --------------                     ------------------------
   4      MON.ID1  (sense0) --|
   7      MON.ID2  (sense1) --|
   11     C&VSYNC.GND --------|

   5      GRN.VID  -----------------> Tip (signal)
   Shell  CHASSIS.GND --------------> Sleeve (ground)

By grounding pin 4 and pin 7 to pin 11, the Macintosh Quadras are told that
an NTSC monitor is attached.  The actual black and white video signal is
on pin 5 and connects to the center (Tip) of the phono-plug.  The shell of
the card connector connects to the sleeve of the phono-plug.

To acquire a color NTSC signal from a Quadra (or any Apple Macintosh
display card), an RGB-to-NTSC converter is required, such as those
available from RasterOps, Truevision, and Computer Friends.  Sorry, but I
do not have the cable requirements for any of these devices.

The third article will detail the amount of VRAM needed for various pixel
depths for all the display configurations supported by the Quadra onboard
video.


*********************************************************************
* Dale Adams             *   Opinions expressed are not necessarily *
* Apple Computer, Inc.   *   those of my employer.                  *
*********************************************************************
--
 ...Doug Bitting... || "But the wisdom that comes from heaven is first
                    ||  of all pure; then peace loving, considerate,
[e-mail] ||  submissive, full of mercy, and good fruit,
[e-mail]  ||  impartial and sincere."  -- James 3:17
--
--
Minnie Mouse is a slow maze learner.


Article 15040 of comp.sys.mac.hardware:
Path: boulder!agate!ames!elroy.jpl.nasa.gov!swrinde!mips!think.com!yale.edu!cs.yale.edu!bitting-douglas
From: [e-mail] (Douglas Bitting)
Newsgroups: comp.sys.mac.hardware
Subject: REPOST: Mac Quadra Video Explained, Part 3/3
Summary: (Was: Re: Quadra + VGA monitor?)
Message-ID: <[e-mail]>
Date: 28 Feb 92 15:38:04 GMT
Sender: [e-mail] (Usenet News)
Organization: You gotta be kidding me!
Lines: 106
Nntp-Posting-Host: zoo-gw.cs.yale.edu


Several people have made allusions to the posts from November 1991 by
Dale Adams, the designer of the Quadra's internal video.  As luck
would have it, I did save these out of curiosity.  So, here is a
repost.  It is in 3 parts.  This is part 3.  This is reposted without
permission; I hope Dale doesn't mind.

--Doug

-- snip here --

> From: [e-mail] (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.                  *
*********************************************************************
--
 ...Doug Bitting... || "But the wisdom that comes from heaven is first
                    ||  of all pure; then peace loving, considerate,
[e-mail] ||  submissive, full of mercy, and good fruit,
[e-mail]  ||  impartial and sincere."  -- James 3:17
--
--
Minnie Mouse is a slow maze learner.