Using An Apple II Monitor On A Mac

 

 

Date: Tue, 8 Sep 1998 01:35:54 -0700
To: Classic Posts <classic-post@hitznet.com>
From: Mike Ford <mikeford@netwiz.net>
Subject: Cheap NTSC video output

BTW yesterday I dumpster dived and pulled out 3 old Apple II monitors, a
A3M0039, and a couple of A2M2056 (something like that) green screens. Why
mention that to a classic mac list? Simple, there is a very easy to make
cable (short the correct pins in the DB15 connector to say NTSC in monitor
sense code, then just a plain coax ending in a RCA video plug) that allows
most 8 bit apple video sources to display in gray scale on these old
monitors. I have one right now on my IIx, and while it is funky looking, it
allows all you need for simple functions like maintaining a server. The
price is good anyway.

[MODERATOR:]

     I'd love to see the schematic for this - can you ascii one?

[END MODERATOR]

Info below is snipped from this
http://developer.apple.com/technotes/hw/hw_26.html

Note it says Quadra, but is generally true with ALL Apple 8 bit video
cards. The cable takes just a few minutes to wire up, and the output is
greyscale. The NTSC is a bit iffy, some VCR may not sync, but most TVs will
display fine.

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, and so on). "Tip" is the pin in the center of the connector (the
signal); the sleeve is the 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 Quadra computers 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.