Isaac_K_Rabinovitch@cup.portal.com (01/12/88)
rshuford@well.UUCP (Richard S. Shuford) writes:
->The original IBM Color/Graphics Adapter (CGA) has been much maligned for
->its low resolution, but the resolution was fixed at that level so as to
->enable the CGA to drive a regular TV set through an RF modulator. (It
->can also be used with a regular EIA video monitor.) The composite video
->output of the CGA is very close to being an NTSC signal by itself.
Whoops! You've just let slip something important. Is there any off-the-shelf
item that will do this conversion? Gotta be standard stuff, I'm not a
hardware hacker.
My situation is, I have CGA hardware but no monitor. I suspect this situation
is common: CGA cards are very cheap now, and CGA capability seems to come
for free with most laptops. But I'm not willing to shell out for a monitor
because the only software that seems to benefit from color is games, and
I'm unwilling to spend $300 bucks to get slightly more realistic games!
(Admitedly applications software looks *nice* in color, but that doesn't
make it more usable!) But like a lot of people I have a TV set with
a video in jack, and it makes a servicable composite monitor.
Obviously, the conversion can be done, but can it be done easily? Or would
it be cheaper to just buy an RGB monitor?
Isaac Rabinovitch
Disclaimer: Just because I think you're wrong, doesn't
mean I don't think you're a fun person!
:-)leonard@bucket.UUCP (01/17/88)
There seems to be a misunderstanding here. The _original_ IBM CGA cards and some of the clone cards have a pair of RCA jacks on them in addition to the DB-9 connector. Both jacks are composite.I have been told that one doesn't have a chroma signal, but I don't know for sure. I have been using them for several months with a _monochrome_ composite monitor. I tired using the video in jack on a 5" color TV but still got black & white. I have seen mention of a problem getting some tvs to display color when they are hooked up to a CGA.... If you don't have the RCA jacks, you can't use a composite monitor unless someone does a lot of hardware hacking for you. If you do, and your tv doesn't have a video-in jack, Radio Shack sells an rf modulator for $26.95. I haven't bought one yet so I don't know how well it works. -- Leonard Erickson ...!tektronix!reed!percival!bucket!leonard CIS: [70465,203] "I used to be a hacker. Now I'm a 'microcomputer specialist'. You know... I'd rather be a hacker."
tj@gpu.utcs.toronto.edu (Terry Jones) (01/20/88)
I hooked my clone up to a tv. It is ugly but fine for some games etc. I used the RF modulator approach at first and had problems. No colour. So I took my clone into worg and hooked up the RGB and got colour. Hooked up the colour composite and got no colour!! It turned out that the shop that had assembled the clone had not adjusted the motherboard clock properly. The 3.579545MHz colour signal for the composite is derived from the master clock and this needs to be adjusted properly. Hook up your machine to a colour composite and adjust the trim cap near the crystal usually located near the back of the machine. This is a very small value trimmer capacitor and the capacitance of the screwdriver you use will usually affect the adjustment. There are special trimmer adjusters for this. They are totally plastic except for a tiny sliver of metal that fits in the capacitor slot. real low capacitance. I used a regular screwdriver and all you have to do is adjust it a bit then back away from it to see if you are there. You can get the diagnostic disk to generate a colour bar or else go into PROCOMM and use Alt-Z to set colours!! Have fun.