Subject: REPOST: Mac Quadra Video Explained, Part 2/3
From: [email-masked] (Douglas Bitting)
Date: 28 Feb 92 15:36:14 GMT
Newsgroups: comp.sys.mac.hardware

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: [email-masked] (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,
[email-masked] ||  submissive, full of mercy, and good fruit,
[email-masked]  ||  impartial and sincere."  -- James 3:17
-- 
--
Minnie Mouse is a slow maze learner.