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Adapter to use IIGS's RGB output on modern VGA/SVGA monitors (idea?)
I've been looking for an adapter, or combination of adapters, that can
be used to view the RGB monitor output of an Apple IIgs on a modern
VGA/SVGA monitor. (I already have a dual monitor setup on my Macintosh
G3, one being an SVGA monitor and one being a Macintosh-style Dsub 15
monitor, and just don't have any more space to add a third.) I've
hoped and dreamed for a Second Sight card, but no one on earth seems to
want to sell theirs (presumably for good reason).
The adapter in question would need to be able to input the RGB signal
from the IIgs as separate red/green/blue component signals, use
double-scan conversion to convert the 15.75 kHz horizontal scan rate
(matching the NTSC standard) of the GS RGB output to at least 31.5 kHz
to work on a VGA monitor, and output VGA-compatible video. (Sure, I
could use the GS composite video out port and use a composite-to-VGA
converter, which I've seen many of on the Web, but then I'd be limited
to composite video quality.)
So far, this is the only thing I've found that's sparked my mind as
having a chance to do the job:
AV converter 4 in 1 box Ypbpr in RGB Monitor
http://www.bryce-max.com.hk/AV%20converter%204%20in%201%20box.htm
Would something like this work? According to the description of this
product on the page, I gather that it can input component video
matching the NTSC standard in YPbPr format. The best definition of
YPbPr I've been able to find is:
---begin
YPbPr
A component analog video signal containing one luma and two chroma
components. Often referred to loosely as YUV or Y, B-Y, R-Y.
YUV
In the general sense, any form of color-difference video signal
containing one luma and two chroma components. Technically, YUV is
applicable only to the process of encoding component video into
composite video. See YCbCr and YPbPr.
---end
I'd like a better definition of YPbPr to know if it would work. I am
hoping that I could possibly construct a cable that connects to the GS
RGB port via the Dsub-15 connector, and feeds the necessary signals
individually into the coaxial RCA jacks on the converter box. Would
this work with no additional signal manipulation required?
-------------------------------------------------
As an addendum, I've included the IIGS monitor port pinout from
R023PINOUTS.TXT and the specs of the original monitor from the Apple II
MONITOR FAQ:
026- What are the specs and pin-out for the GS RGB monitor?
Max Resolution: 640 Horizontal dots x 200 Vertical dots/lines
Dot Pitch: .37mm
CRT Size: 12"/ 11.5" viewable
Video Bandwidth: 6.5MHz (+/- 1.5DB)
Scanning Frequencies
60Hz model 50Hz model
Horizontal: 15.734kHz 15.696kHz
Vertical: 60Hz 50Hz
___________________________
IIGS RGB Connector
Note: "Not used" indicates signals not used by the IIgs RGB monitor.
Dsub-15 (female) socket at back of IIgs
,--------------------------------.
\ 08 07 06 05 04 03 02 01 /
\ 15 14 13 12 11 10 09 /
`----------------------------'
|
|
pin # signal |
|
shell system ground
1 ground (for red)
2 red analog video
3 composite sync
4 (not used)
5 green analog video
6 ground (for green)
7 -5 V (not used)
8 +12 V (not used)
9 blue analog video
10 (not used)
11 audio output (not used)
12 composite video (not used)
13 ground (for blue)
14 (not used)
15 (not used)
____________________________
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