[comp.sys.mac] NTSC from Mac II?

chris@acrux.usc.edu (Christopher Ho) (09/04/87)

I seem to have read somewhere that Apple's Mac II video card can put out
its analog RGB signals at NTSC frequencies.  My Mac II's on order, so I
don't know if the documentation reveals this, but I'd like to know how
this is done.  With the dearth of Apple color monitors, I'd like to at
least TRY hooking up a Sony KV-25XBR or an Amiga monitor, even if the
picture quality isn't great.

chris@oberon.usc.edu				LA/LB HHH: Headless

stew@endor.harvard.edu (Stew Rubenstein) (09/05/87)

In article <4314@oberon.USC.EDU> chris@acrux.usc.edu (Christopher Ho) writes:
>I seem to have read somewhere that Apple's Mac II video card can put out
>its analog RGB signals at NTSC frequencies.  My Mac II's on order, so I
>don't know if the documentation reveals this, but I'd like to know how
>this is done.  With the dearth of Apple color monitors, I'd like to at
>least TRY hooking up a Sony KV-25XBR or an Amiga monitor, even if the
>picture quality isn't great.
>
>chris@oberon.usc.edu				LA/LB HHH: Headless


The word on compuserve when this was discussed a while ago, if I
remember correctly, was that the one person at Apple who really
understood the Mac II video board knows how to do this with a video
board ROM change, but that he had higher priority projects.  So the
answer is, pressure Apple to release this ROM through any means you
have available.

Stew Rubenstein
Cambridge Scientific Computing, Inc.
UUCPnet:    seismo!harvard!rubenstein            CompuServe: 76525,421
Internet:   rubenstein@harvard.harvard.edu       MCIMail:    CSC

afoster@ogcvax.UUCP (Allan Foster) (09/06/87)

In article <husc6.2801> stew@endor.UUCP (Stew Rubenstein) writes:
>In article <4314@oberon.USC.EDU> chris@acrux.usc.edu (Christopher Ho) writes:
>>I seem to have read somewhere that Apple's Mac II video card can put out
>>its analog RGB signals at NTSC frequencies.  My Mac II's on order, so I
>>don't know if the documentation reveals this, but I'd like to know how
>>this is done.  With the dearth of Apple color monitors, I'd like to at
>>least TRY hooking up a Sony KV-25XBR or an Amiga monitor, even if the
>>

Newsgroups: comp.sys.mac

I have done it.  The picture leaves a lot to be desired but
then again I was projecting it with a normal home big screen
tv.  I wrote a control panel CDEV to do the switching so
I will try to find it and post it as soon as I can.  One
serious problem with the cdev is that it only gains control
after the boot up so for a few seconds you have normal mac
video coming out.  The way I fixed this was to put a beep
into the cdev and not to connect the video until it had executed.

If you need any more info please contact me.

Allan Foster

patm@omepd (Pat Mead) (09/08/87)

In article <2801@husc6.UUCP> stew@endor.UUCP (Stew Rubenstein) writes:
>In article <4314@oberon.USC.EDU> chris@acrux.usc.edu (Christopher Ho) writes:
>>I seem to have read somewhere that Apple's Mac II video card can put out
>>its analog RGB signals at NTSC frequencies.  My Mac II's on order, so I
>>chris@oberon.usc.edu				LA/LB HHH: Headless
>
>remember correctly, was that the one person at Apple who really
>understood the Mac II video board knows how to do this with a video
>board ROM change, but that he had higher priority projects.  So the
>answer is, pressure Apple to release this ROM through any means you
>have available.

At our last users group general meeting a local mac programmer hacked together
an init that allowed the Mac II's video board output to go directly to a large
screen (NTSC) TV. It was done in software!! I know since I helped him debug it
in the first of the meeting. The output of graphics was ok but reading text was
not very good at a distance. If there's a demand for this maybe I can talk him
into posting it. When you use the init NO output will be seen on your mac 
screen only on the NTSC monitor. Which means you must boot from elsewhere to
remove the init to use your mac monitor again. It would be nice if you could
use both at the same time.

***********************************************************
usual disclaimers---	

Patrick Mead			ogcvax!inteloa!omepd!patm

***********************************************************

olson@endor.harvard.edu (Eric Olson) (09/10/87)

In article <1033@omepd> patm@omepd.UUCP (Pat Mead) writes:
>At our last users group general meeting a local mac programmer hacked together
>an init that allowed the Mac II's video board output to go directly to a large
>screen (NTSC) TV. It was done in software!! I know since I helped him debug it
>in the first of the meeting. The output of graphics was ok but reading text was
>not very good at a distance. If there's a demand for this maybe I can talk him
>into posting it. When you use the init NO output will be seen on your mac 
>screen only on the NTSC monitor. Which means you must boot from elsewhere to
>remove the init to use your mac monitor again. It would be nice if you could
>use both at the same time.

OK, we now know that someone wrote an INIT to make the scan rate/interlace
correct, and someone else wrote a cdev to make it right while running (the
cdev's drawback was that you can't connect the video during boot, because it
will be set for the Mac II screen and might fry (?) the NTSC monitor).

What remains to be revealed is how to wire it up?  Where do I connect the
puppy?

-Eric




Eric K. Olson		olson@endor.harvard.edu		harvard!endor!olson

bc@mit-amt.MEDIA.MIT.EDU (bill coderre) (09/11/87)

I really doubt that MacII video (or the equivalent PGA) will fry a
monitor. I did try it, once.

Natch, I can't vouch for your Philco 7"........................bc

patm@omepd.UUCP (09/11/87)

In article <2818@husc6.UUCP> olson@endor.UUCP (Eric Olson) writes:
>
>OK, we now know that someone wrote an INIT to make the scan rate/interlace
>correct, and someone else wrote a cdev to make it right while running (the
>cdev's drawback was that you can't connect the video during boot, because it
>will be set for the Mac II screen and might fry (?) the NTSC monitor).
>
>What remains to be revealed is how to wire it up?  Where do I connect the
>puppy?
>

Actually Alan Foster (the writter of the cdev) is the same person I was taking
about. He has since having it as an Init changed it to being a cdev. I didn't
want to say who it was in case he didn't want to post it. But he has posted it
now and I'm sure he will also reply on how to wire it up. Please send all 
further replys to him at ogcvax!afoster.

It's great to have such great people on the net that we can get code to do what
ever our mac's are able to do and beyond! Thanks to all that have posted public
domain software and shareware so we all can enjoy our mac's all the more.

***********************************************************
usual disclaimers---	

Patrick Mead			ogcvax!inteloa!omepd!patm

***********************************************************

afoster@ogcvax.UUCP (Allan Foster) (09/12/87)

Let me clarify some confusion here.

Pat Mead mentioned that someone in the user group hacked together
an init to run NTSC.  Someone also wrote a cdev to do it.
That someone was the same person .... ME.

The cdev and the INIT were the same thing, as the cdev was
used to configure the init.  As cdev's are also loaded
as INIT's are at boot time it works fine.

The problem about frying the monitor happens anyway
as the init takes a few seconds to actually happen
so before this there is a time of frying experience!!!

I have posted the source for changing the video to NTSC and
back.  If there is enough demand I will also post the cdev
Ahhh what the hell, I will post the cdev anyway.

Regards Allan


#include "std_disclaimers"