Mail Archive - Plus/4 World



	Home Search Games Tapes Covers Cheats Maps Software New Stuff Hall Of Fame HVTC Game Endings Solutions Remakes Publications Magazines Effects Top List Members Groups Features Plus/4 Encyclopedia Hardware Tools Options Forum Home Search Games Tapes Covers Cheats Maps Software New Stuff Hall Of Fame HVTC Game Endings Solutions Remakes Publications Magazines Effects Top List Members Groups Features Plus/4 Encyclopedia Hardware Tools Options Forum	Login

Previous | Next

From: TLC (all posts)
Date: 2000-04-16
Subject: Re: Questions

Hi!,

[Csabo]

You should obtain an American Plus/4 power supply (even a C64 power supply will do, if your machine has the 'round' type ps connector instead of the mostly common square one). It will work with no problems at all. Unlike the C64, the Plus/4 has no parts inside that depend on the 50 or 60 Hz mains frequency.

If it's not possible, you'll find the Plus/4 schematics somewhere on Funet (or if not: I could scan it myself), so somebody with good soldering skills could help you in hacking one. The PS has nothing special inside - just a transformator with two output 9v circuits, one going directly to the Plus/4 and the other going through a rectifier /
buffer / regulator stage, resulting in the needed (some above) 5v DC.

You'll have problems with the American NTSC-M standard TV sets, however.
But don't worry - most new TV's handle both PAL-B (European) and NTSC-M videosignals. It's probably the best to connect the units directly,
using a cable from the video output connector on the Plus/4, to the SCART connector of the TV. I don't know if the European RF modulator generates suitable signal for NTSC TV's

rbernardo wrote:
> However, you'll run into the problem of the crystal timing of the
> Euro PAL Plus 4 will be thrown off by the American p.s.. The crystal
> expects 50 HZ. but will be receiving 60 HZ.. The video chip also expects
> a 50 HZ. frequency but will receive 60 HZ.. This means that the video you
> will see will lose its color information (i.e., you'll get a
> black-and-white picture), and the screen will flicker terribly. PAL
> programs used on such a Euro PAL/American p.s. machine will not act
> correctly to keypresses or other input. (I received several PAL programs
> from Peter Hanson, such as Flight Simulator 2 for the Plus 4. However,
> they don't work correctly with my Euro PAL/American p.s machine. They do
> work correctly with a PAL Plus 4, Euro p.s., and PAL monitor -- which
> Peter has.)

I don't know why FS2 didn't start on your PAL machine, but the operation of the Plus/4 doesn't depend on the 50/60Hz wall outlet frequency in any ways. What you mentioned, reminds me to the the C64 and the C128, since these machines actually make use of the 50/60 Hz ticks that come with the power voltage, but not the Plus/4 for sure. Neither these machines BTW generate B/W video signal + flickering because of this difference,
since they only use this source as the base of their real time clock
(the CIA chips support RTC functions by hardware).

(If I started, I continue it - maybe it will be useful for someone). The difference between the PAL-B and NTSC-M standards are in the screen refresh frequency, the number of scanlines and the way the colors are encoded in the composite signal. The TED chip in the Plus/4 can generate both, if you provide the right crystal on the mainboard. The PAL standard defines 625 scanlines @ 25Hz (or 312 lines @ 50Hz in non-interlaced mode, like the Plus/4 does), while NTSC does 525 lines @
30Hz (262 lines @ 60Hz non-interlaced).

If anybody is to fix European Plus/4 software for NTSC machines, all he should be aware of are the less scanlines per frame (only 262 lines instead of 312, so whenever a program waits for a scanline beyond 262,
it'll go into an infinite loop (or a never occuring interrupt) for sure), and the 60 Hz screen refresh (for example, musics called from the raster interrupt routine must be fixed in order to play slower - the easiest way for this is to skip calling the player routine in every sixth frame).

(Just a note: switching the $ff07 register bit6 to PAL or NTSC mode doesn't mean you have the valid PAL or NTSC videosignal on the output,
since the two modes need a different crystal to be in the oscillator circuit - 17.73 Mhz for PAL and 14.318 Mhz for NTSC).

> I'm here, though I could be more active. Good luck on your mega
> demo. My need is to find a good source of NTSC Plus 4 programs. I had a
> source in Los Angeles, though I don't know if he's still in
> business. Does anybody know of a website or other source of NTSC Plus 4
> programs?

Unfortunately, not - but years ago, Jim Hehl did a lot of programs for NTSC machines - he has a website somewhere for sure.

L.