On Mon, 9 Nov 1998, Hans Franke wrote:
> Maybe this adds some interferences - but are you shure you
> had 50 Hz display, or a 50 to 60Hz full screen conversation ?
> Often they just add pictures wich results in a strange effect
> giving a kind of cartoon feeling.
I've seen this effect on a few shows, but I was referring to demos on the
computer. I think maybe I just have 60Hz eyes. :)
> > Less horizontal lines? Televisions are analog horizontally, and all of
> > the computers I know of generate the same number of pixels horizontally
> > whether they're in Europe or North America.
>
> Shure, they are analog, but still a real world application.
> And every signal needs time to rise and fall. And since
> analog isn't digital (in fact nothing is digital in real
> world), the signal has to go from black to white thru
> all shades inbetween (and all shades will be transmitted :).
> Only a digital signal could go from blac to white without
> any delay - but as I said before the world isn't digital
> even digital signals are analog and need their time between
> their levels.
OK, understood.
> > Certain European Amiga models would be able to generate 60Hz PAL. I don't
> > know what else could, but I've never come across a European computer.
>
> Same for Atari STs and AFAIR C64s, almost all MSXes...
I don't think the C64 has this capability. I have a C64 that has been
modified to do PAL, with an external toggle linked to two oscillators
inside, but I was told that I'd also need a PAL VIC-II chip to run PAL
demos.
> > they often completely fail to run on 60Hz screens. (I think they take
> > pride in making their programs not work on North American computers.)
>
> Maybe the same ignorance as US programmers have for any spot
> outside their littele hometown ? Serious, these demos are
> so tight packed with the FBAS / TV timeing that changing any
> parameter just kills funktion, especialy on the C64. If you
> want to manipulate scrren colours within a screen line (hor.)
> the CPU cycles are just attached to the colours, content and
> FBAS timing. And a screen line (hor.) in PAL is about 62.5 us
> while a NTSC line is 57us (AFAIR). So, PAL allowes up to 3
> additional 6502 operation to be performed within a line.
> These demos are sometimes real tight ...
I was aware of this on the C64, but the Amiga has more horsepower and I
find it hard to believe that that many demos are coded that tightly.
Besides, I have a couple of demos that require that I first run Degrader
on my A3000 or A1200, using "50HzSystem" mode (not just "50Hz"). They
don't work at all otherwise. BUT, my Amiga 1000, which is 60Hz-only, runs
these very same demos with some minor screwups here and there. (Curiously,
my A1000 is often identified as a PAL system by programs like SysInfo, but
it's pure NTSC, 60Hz. SysInfo also identifies my A1060 SideCar as an
A2286. An A2088 maybe I could understand, but A2286?).
One of these curious demos is "Desert Dreams" by Kefrens. It runs well
into the second disk before crashing my A1000. It freezes at the blinking
cats' eyes at the beginning of the demo with my A1200 or A3000 if I don't
use "50HzSystem".
> > There are still demoparties in Europe with prizes for Amiga and C64
> > entries.
>
> Shure - they are BIG events - sometimes several hundred
> participants.
Sounds like a lot of fun! I wish I could go. :)
> >> I used an SONY TV for the ATARI ST, 10 years ago.
> > My brother used a Sony TV for his C64. Which kind of sucked because it
> > only had composite input.
>
> I just mentioned SONY as an example for Japaneese TV where
> SCART and RGB and 50/60 Hz switch are common features since
> more than 10 years.
Not on this side of the Atlantic. S-Video if you're lucky.
> Servus
> Hans
>
> --
> Ich denke, also bin ich, also gut
> HRK
--
Doug Spence
ds_spenc_at_alcor.concordia.ca
http://alcor.concordia.ca/~ds_spenc/
Received on Mon Nov 16 1998 - 03:54:43 GMT