Re: ZXmore - infos & updates
Posted: Fri Jul 21, 2017 3:06 am
Not to rain too much on your parade, but I have a bit of, okay a large OCD thing about video standards.
PAL is only a colour encoding system, NOT a video or TV standard. PAL can encode colour for 525 line, 15750 Hz horizontal, 60 Hz vertical (field) / 30 Hz frame TV video signals (as used in Brazil). So PAL does not always mean a 625 line 50Hz video signal.
Conversely, it is possible to encode colour for a 625 line 50Hz video signal using NTSC. In France, they did not use PAL or NTSC, instead they used SECAM to encode the colour part of the video signal. And yes, NTSC 625 line 50Hz video has been tested and found to work okay.
In Germany and the UK, ZX80, ZX81, ZX Spectrum's, and of course, the two computers developed by Karl all generate 625 line, 15625 Hz horizontal, 50 Hz vertical (field) video signals (in the UK, this is known as the ITU standard system I). As ZX80, ZX81 and Karl's designs don't produce colour video, they don't have a colour encoder system. So PAL/NTSC does not apply. The ZX Spectrum does use a colour encoder, so does produce a PAL colour signal.
So to sum up:
USA colour analogue TV used the ITU NTSC-M standard.
UK colour analogue TV used the ITU PAL-I standard.
French colour analogue TV used the ITU SECAM-L standard.
In the USA, TS1000 computers use the ITU M standard.
In the UK, ZX81 computers use the ITU I standard.
Broadcast television systems and Analog television - Standards
Mark
PAL is only a colour encoding system, NOT a video or TV standard. PAL can encode colour for 525 line, 15750 Hz horizontal, 60 Hz vertical (field) / 30 Hz frame TV video signals (as used in Brazil). So PAL does not always mean a 625 line 50Hz video signal.
Conversely, it is possible to encode colour for a 625 line 50Hz video signal using NTSC. In France, they did not use PAL or NTSC, instead they used SECAM to encode the colour part of the video signal. And yes, NTSC 625 line 50Hz video has been tested and found to work okay.
In Germany and the UK, ZX80, ZX81, ZX Spectrum's, and of course, the two computers developed by Karl all generate 625 line, 15625 Hz horizontal, 50 Hz vertical (field) video signals (in the UK, this is known as the ITU standard system I). As ZX80, ZX81 and Karl's designs don't produce colour video, they don't have a colour encoder system. So PAL/NTSC does not apply. The ZX Spectrum does use a colour encoder, so does produce a PAL colour signal.
So to sum up:
USA colour analogue TV used the ITU NTSC-M standard.
UK colour analogue TV used the ITU PAL-I standard.
French colour analogue TV used the ITU SECAM-L standard.
In the USA, TS1000 computers use the ITU M standard.
In the UK, ZX81 computers use the ITU I standard.
Broadcast television systems and Analog television - Standards
Mark