Some video signals questions

[TuZhao]

After having read lots of articles around, I have still some doubts (my friends ask me questions which put me in trouble):

1. Can we talk of NTSC RGB and PAL RGB as two different things? RGB is just RGB, isn't it? There's 50 Hz RGB and 60 Hz RGB, and that's it. Or not?
2. S-Video can indeed be either NTSC or PAL, right?
3. When someone talks about RGB TTL opposed to analog RGB referring to VGA monitors, what does he mean by TTL? Has it got something to do with Transistor-Transistor-Logic referred to a family of IC's?
4. If VGA monitors accept a digital RGB signal, where's the difference between that digital signal and DVI?
5. Why video cards don't have a pretty RGB output, instead of the usual composite one or the useless (at least in Europe) S-Video one? Is that so expensive?

Thank you for the answers, and feel free to use every techie jargon you know

[NFG]

1. Correct.
2. Correct.
3. TTL is digital, and is usually referring to EGA-style monitors.
4. Digital can come in many flavours, DVI is just one standard.
5. They do, the VGA port can often be used for TV-standard RGB with the right software.  

[Darklegion]

5.RGB isn't used by many people outside of europe so they don't bother putting the connectors on.Most tv-out chips output it though,so you can hack it in yourself,here is a link to a page of someone that did just that:
http://www.bitmonster.com/rgb/
Its in german but the schematics are readable....and you can run it through an online translator if you want to read it.Its for cx2587x series,common in geforce 4 ti video cards,among others.Its the same chip that the xbox uses I believe...well the early model xboxes.

Also you can do it through the vga cable as well like lawrence said,also requiring you to make a cable hack.Might be a bit dangerous though if the program controlling this doesn't load at startup for any reason,and ends up sending a vga sync signal to  your tv.Probably won't damage it though,as long as you turn your tv off immediately if this ever happens.

[Endymion]

4. If VGA monitors accept a digital RGB signal, where's the difference between that digital signal and DVI?

VGA is an analogue signal, DVI is digital, although there are two kinds, DVI-I (can send digital and analogue) and DVI-D which can only send a digital signal, this one will not work with standard VGA CRT's. Because VGA monitors accept an analogue RGB signal...

[TuZhao]

I read somwhere (perhaps on Dan's Data pages) that TV's and other 15 kHz monitors accept only analog RGB while PC's VGA output is digital (called RGB TTL - what does TTL mean?). I always believed that VGA was analog :unsure:
Do CGA (320x200x2 bit) and MCGA (320x200x8 bit) output a 15 kHz signal?

To Lawrence: my first question was confusing, sorry With "correct" you mean that RGB is independent from NTSC and PAL?

Darklegion: thanks for the link, it looks interesting (moreover, I am currently studying german so that page comes handy for learning )

[Endymion]

I read somwhere (perhaps on Dan's Data pages) that TV's and other 15 kHz monitors accept only analog RGB while PC's VGA output is digital (called RGB TTL - what does TTL mean?). I always believed that VGA was analog

You are correct. VGA is analogue, and always has been. Old computer video standards, that is, video standards used with computers so old that you don't want to use them were digital--those were the TTL types, and preceded VGA. EGA, CGA, all of the weird-but-still-floating-around type terms like that, most of them were digital. The move to analogue was made precisely because it was too difficult and costly to produce hundreds, thousands, and millions of colours with digital signals. VGA is all analogue, and always has been. It's just at a higher sync rate than the TV standards, that's all.

[LocalH]

To Lawrence: my first question was confusing, sorry With "correct" you mean that RGB is independent from NTSC and PAL?

Yeah, RGB, is RGB for the most part. I believe there might be a SLIGHT level difference, but I don't know how much off the top of my head. I do know that many Commodore 1084 monitors will happily sync at 50Hz with the right RGB signal (I've done it with my Amiga, both software-switched and jumpered on the mobo). NTSC and PAL are color encoding standards, they are applied to RGB signals. So really there is no 'NTSC-RGB' or 'PAL-RGB' but just 50Hz and 60Hz RGB.

[TuZhao]

So really there is no 'NTSC-RGB' or 'PAL-RGB' but just 50Hz and 60Hz RGB.

Thanks, that's what I wanted to hear
According to this, and according to the specs of my Hantarex MTC9000 (V. freq range: 47-70 Hz), that monitor should handle any PAL or NTSC console that outputs RGB. My JAP Saturn displays fine, while my PAL Dreamcast not. Colors are OK, but the image is screwed up.
Could it be just a matter of composite sync missing from the DC video out? The Saturn does have it, while I don't know if the DC does. I'd better check the pinout  

Back to the VGA and RGB questions, how do those VGA to PAL transcoders (like the Trust Televiewer) work? How do they cut the 31 kHz signal down?

[ozpass]

(called RGB TTL - what does TTL mean?).

TTL stands for Transistor-Transistor-Logic and it refers to a way of implementing logic gates with transistors.

In the context of what we're describing here, it should strictly be called "TTL-level" which refers to digital signals at the 5V, 5mA rating used by TTL (and CMOS) implementations.

[TuZhao]

In the context of what we're describing here, it should strictly be called "TTL-level" which refers to digital signals at the 5V, 5mA rating used by TTL (and CMOS) implementations.

Thank you, that was exactly what I thought (reminescence of secondary school), but I needed a confirmation