Developer Forum

Wanted: 50 hz boot disk (original or copy)

I used to have a copy of a 50 hz boot disk that someone from the UK
sent me(later corrupted by a virus), I think the program was in an
autorun folder and simply called "50hz.prg". It always worked great
for me. Quite a few (original copy protected) games would not run
without it. I tried downloading one with the same filename off of an
FTP but it didnt seem to work as well as the one I used to have. If
anyone has this program, especially an original copy of it, let me
know I would be glad to paypal a few bucks for it plus postage. Also
if there are any other programs that do the same thing I would like as
many different 50hz booting programs as possible to try on various
game software that is stubborn on US machines.

Does anyone know if it is possible to use a 50hz computer here in
the US? I don't understand where the 50 or 60hz default comes from,
the TOS (ie UK TOS), the monitor, or somewhere esle. I have always
been confused by the Atari ST US/Europe 60hz 50hz phenomenon and am
looking for a way to maybe have one computer set up to run the
stubborn european games/demos without having to tweak it with a boot
disk. (such as can be done with various consoles etc.) Thanks for any
answers someone can give me. -SaTcom2

On 5 Apr 2004 17:20:24 -0700, XXXX@XXXXX.COM (CrimKingson)



Get it from:
http://www.yqcomputer.com/ ~archive/atari/

JM

The 50/60Hz comes from the mains electricity standard. Your mains is 110V @
60Hz, ours is 220v @ 50Hz. That was put in place donkeys ago. Tv's used to
use the main for a sync signal for the screen, so you would have a 60hz
vertical refresh. When computers came out that used the TV the video
hardware had to match this frequncy or the picture would roll and sometimes
worse. These days on modern TV's its not an issue anymore as TV's generate
the clock themselves.

Regarding your ST, I never used one in the states, so I dont know about
frequency compatibilty problems, I thought they was non existent - but I did
sometimes run mine at 60hz, most games disks (not originals but menus) have
an option to switch 50/60. Games soemtimes ran faster, or at least the music
did.

Changing the frequency is a simple matter of a bios call. A program can be
knocked together in a couple of minutes. The problem is getting it to stay
at 60hz while you reboot so you can load the game. It can be done.

In message <c4tpjn$io6$ XXXX@XXXXX.COM >, XXXX@XXXXX.COM said:


Not quite. TV sets didn't use the mains frequency as a sync signal
- that was always in the transmitted waveform. But early TVs in
particular did not have very good smoothing on the EHT (extra high
voltage) supply for the tube, which was transformed from mains and
rectified. Manufacturers claimed high voltage rating smoothing
capacitors of higher values were too expensive. As a result there
would be a slight change in brightness across the tube face, known
as a hum-bar. When this was stationary, you could hardly see it.
But if the sync requency differed from the local mains frequency,
the bar moved up or down the screen, and that *was* easily
visible, and annoying. That's why sync was locked to the mains -
fine for people on the grid in the UK, which was synchronized over
most of the country, but not elsewhere (such as N. Ireland and
some islands, which had their own power networks or mainland Europe.)

Later, EHT was derived from the flyback pulses from energy stored
in the scanning coils, and that problem went away. When NTSC
colour was introduced in the USA, the field frequency had to be
changed slightly to prevent interference between the frame
frequency and the colour subcarrier (which is locked to the line
frequency), and is now something like 59.9-odd Hz. In '50 Hz
countries' (using PAL or SECAM) the field and line frequencies are
also locked to the colour subcarrier, but the field frequency
coincides with 50 Hz.

Most modern TV sets and some monitors will happily synchronize to
both 50 and 60 Hz field frequencies (and higher for PCs or Macs at
high screen resolutions). But older computers such as the Atari
and Amiga may have to use an uncoded video (preferably RGB)
connection for use in countries with different TV standards. This
is because monitors that accept TV-style signals normally only
decode either PAL or NTSC. Modern TVs in Europe, at least, will
accept NTSC signals - not sure whether US TVs will accept PAL.

Regards, /Peter/

Hi

IIRC the frequency 50/60hz for the ST's alter the monitor output
frequency. 60Hz (US) gives a bigger picture (less of a border) and
slightly faster speed performance here in the UK. Over here some old tv
and monitors dont like anything but 50hz.

By the sound of things it looks like ye olde internal timing and
compatibility problems. I have found that running another TOS version -
disk based - may also help. I use the original TOS 1.09 on disk for some
NON STE software without any problems

I have never really had any problems from software that i have had from
the usa, or anywhere in the world come to think of it. Anything that
relies a lot on timing can be thrown off with different versions of
TOS.

If you can look through my library catalogue, sorry not added search
functions to the site yet, you may be able to find the exact program you
are after as there are several that change all manor of things at boot
time:)

www.last-pd.co.uk

Hope this helps

atb
Steve

On Mon, 5 Apr 2004 at 17:20:24 a message from CrimKingson was created on
the subject of 50 hz boot disk wanted ST 50/60 hz question.

--
Cheers! For Now
Steve <>< * * *
Email: XXXX@XXXXX.COM * * *
Tel: +44 01834 812319 * fax: 0870 0521124 'The Fuji Bounces Back'
ICQ: 18116827 * Nick: MocknBird on IRC * * *
Location: Kilgetty, Pembrokeshire, Wales, UK. ** *** **

From a technical point of view I should think that it would be very hard to
get a smooth (sync) signal from the mains, everytime someone switched
someting on in your street your TV would flicker, let along when the TV
adverts come on, mains is not that clean (better now than then).

I also have a suspicion that all (old) B&W sets could run at both 50 and
60Hz, can anyone confirm this? Not sure why?

E.







XXXX@XXXXX.COM said:
@
to

In message <c6u20b$qu0$1$ XXXX@XXXXX.COM >, XXXX@XXXXX.COM said:


You misunderstand. The sync in the TV set was not derived from the
mains, but the sync-pulse generator at the TV station was locked
to the country-wide supply grid so that the sync-pulses were at
the grid frequency. Actually the supply frequency is not really
influenced locally by load changes. With heavy loads over a wide
part of the country, the whole grid may be pulled down by a
fraction of a hertz but that's all. Of course, this does not apply
for some islands etc that are not connected to the grid and may
set their own frequency.


No British TV sets, or German ones, that I saw would take 60Hz TV
standards. Just a few speciliast monitors used in TV stations etc.
were dual-standard. OTOH, the TV set itself would probably run
from a 60Hz supply (though I have never seen such a supply outside
N. America or parts of South America and Japan) - but with the
risk of a 10 Hz rolling hum-bar. Modern colour sets in UK and
Europe, at least, usually handle both 50 and 60 Hz TV standards.
Quite possible that US sets don't, though.


Regards, /Peter/