• Updated 2023-07-12: Hello, Guest! Welcome back, and be sure to check out this follow-up post about our outage a week or so ago.

NTSC Monitor

N

NJRoadfan

Well-known member
Composite color would require the card have a NTSC encoder on it. RGB would be doable though. If the card can output 15.75khz video, those sense pins would be used with a monitor like the IIgs AppleColor RGB or the Commodore 1084.
 
C

cheesestraws

Well-known member
Note that just because a sense code is specified for those monitor types doesn't mean that anything was ever actually released to drive them: it just meant that, at some point, they thought they might release something to drive them.

That said, that weird broadcast video card with the name I can't remember (this is wildly unhelpful; it's got a black PCB and looks really cool, someone here has one and they turn up on buyee relatively often and it's really annoying not even remembering the manufacturer) does broadcast resolutions, and maybe that will use those sense codes?
 
H

halkyardo

Well-known member
I don't believe any Macs were able to output colour composite video from the 15-pin connector, except maybe some specialised video cards (the AV Macs are a different story). The video output is still RGB in those modes, just with resolution and timings suitable for NTSC or PAL.

You CAN however get greyscale composite video from some video cards by setting an NTSC or PAL sense code and using the green channel as the video output. I've done this with an E-Machines Futura SX card in my IIfx, and the RasterOps ColorBoard 264 card in my SE/30 will do it too.

The picture quality is nothing to write home about, but it does work!
 
Phipli

Phipli

Well-known member
So, I think I remember that it's only half the story. Several Apple video cards and built in video supported these modes, but required an external box in combination  to archive it.
 
finkmac

finkmac

NORTHERN TELECOM
++ @Phipli

i know the Macintosh II Toby definitely supports this.. but you need a special cable. There was utility on macintosh garden (that I can't seem to find) that enables this mode.
 
J

joevt

Well-known member
One time, I connected an RGB NTSC CRT to my Power Mac 8600's built-in video output. I think it was a Commodore 1070 display and I had to modify the sync connection inside the display for separate sync. I wonder if an Apple IIGS display could be connected? I think that would require an adapter since some pins are not the same as Mac.

You can connect a NTSC or PAL RGB virtual display to DingusPPC emulator. I need to push a commit to fix the issue where every second line is skipped and the frame rate is set to 30Hz instead of 60Hz.

I had an LC. I think it was limited to 12", 13", and VGA displays. No interlaced displays.
 
N

NJRoadfan

Well-known member
Pin 5 is green video, which also carries sync. When running at NTSC rates = black and white composite video. The Apple IIgs monitor uses the same pinout as the Macintosh DB-15 and only accepts composite sync on pin 3. If you can force the Toby and other machines to 15.75khz RGB with composite sync, it should work fine with the IIgs monitor.
 
H

halkyardo

Well-known member
That’s a good question. Its video output supports a number of different resolutions so having support for an interlaced display wouldn’t be beyond the bounds of possibility. I’d very much doubt if it could do colour composite output, but interlaced 60Hz RGB sounds pretty likely.

You’ve piqued my curiosity though. I’ll dig out my 180c and some adapter cables tomorrow night and have a play around and see what it’ll do.
 
H

halkyardo

Well-known member
The 15.6672 MHz dot clock for 512x384 would also be plausible for an underscanned 640x480i mode, so while it not being listed certainly doesn't bode well, it still wouldn't be beyond the bounds of possibility that it could exist as an unsupported mode. Stranger things have happened.

If I can find some space to set up my 180c and a monitor tonight, I'll experiment and see what it'll do.
 
Phipli

Phipli

Well-known member
H

halkyardo

Well-known member
Just did an experiment with my 180c, and it does *not* seem to recognise a monitor attached with the NTSC Monitor sense code (100), nor PAL Encoder (extended sense 00-00-00) or PAL Monitor (extended sense 11-00-00). So that seems to put paid to that idea, sorry :(
 
N

NJRoadfan

Well-known member
Action Retro's latest video shows a SuperMac SCSI video adapter that can run in 15.75khz mode. Its mostly for the composite video port, but it clearly outputs RGB at the same timings.
 
You must log in or register to reply here.

Similar threads

eharmon
SuperMac HDTV output?
Replies
0
Views
167
eharmon
eharmon
bigmessowires
Apple IIgs PAL video timing?
Replies
8
Views
2K
NJRoadfan
N
bigmessowires
Designing a Mac-to-VGA monitor sync-splitter adapter
2 3 4
Replies
70
Views
4K
LaPorta
LaPorta
croissantking
Apple Multiscan 15AV - can't get it to work with a IIsi/IIci
2
Replies
21
Views
923
volvo242gt
volvo242gt
robin-fo
Apple IIgs with floppy drive
Replies
3
Views
328
NJRoadfan
N
Top