15 Nov
1998
15 Nov
'98
7:54 p.m.
On Mon, 9 Nov 1998, Hans Franke wrote:
OK, understood.
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.
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".
Sounds like a lot of fun! I wish I could go. :)
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.
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. 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... 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 ... There are
still demoparties in Europe with prizes for Amiga and C64
entries.
Shure - they are BIG events - sometimes several hundred
participants. 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. Servus
Hans
--
Ich denke, also bin ich, also gut
HRK
--
Doug Spence
ds_spenc(a)alcor.concordia.ca
http://alcor.concordia.ca/~ds_spenc/