>>No. I've seen 64-column text on typical mid-70s NTSC televisions, and it was
>>abysmal. The televisions had to be modified to remove their color trap
>>in order to get reasonably sharp characters.
> I remember when the Amiga was first launched, its composite output
> was purported to be able to drive 80 columns on an ordinary TV.
> Was it a matter of televisions improving in the same time period,
> or that they might've been talking about monochrome as opposed to
> color?
Jep, thats the main thing I think. And 80 columes are also
hard for B&W TV - 80 columes with 8 bits per character gives
320 lines with less than 200 ns per line. Thats more than
5 MHz - and at 5 MHz the signal would be some sinus like
wave (a 'sawtooth' with heavy rounding), and the resulting
display would be more like gray - ok, of course letters
are not strict lines of black and white, so the resulting
might display characters (together with the highly sophisticated
patern matching machine called brain). For a B&W TV signal
some 200 Lines is a _VERY_ good result, so 80 chars with
6 pixles each (240 lines) might be well readable on a good TV.
Remember, these calculations are only minimal influenced with
the quality of a TV set, but rather fixed by TV modulation
schemes. you just can't fit a 10 MHz signal within a 5 MHz
chanal. Ok, to be honest, the numbers are based on european
TV, since I just can remember them without pain - 50 (half)
pictures per second, 625 lines per (full) picture, 15625
kHz line frequency, 64 us per scan line ... (Just ask me
after beer number 10 :), but basicly the US system comes
to similar numbers when we are down to lines since the
bandwidthe (chanal) is the same.
> Certainly NTSC color has a hard time changing quickly, its
> resolution is only a hundred or so lines across, isn't it, while
> gray-scale resolution is as much four or five times that?
Jep, exactly - you have always to 'runn the colour cycle'
from one colour to the next, so you cant go from bright
yellow to blue without crossing some other colours - and
the speed to go around the cycle is the maximum frequency
of the colour signal.
Gruss
H.
--
Der Kopf ist auch nur ein Auswuchs wie der kleine Zeh.
H.Achternbusch
Received on Mon Dec 14 1998 - 16:00:58 GMT