Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!uunet!mcvax!cernvax!ethz!visinfo
From: visinfo@ethz.UUCP (VISINFO Moderators)
Newsgroups: comp.sys.amiga
Subject: 60 Hz on PAL (50 Hz) Amigas
Summary: Software 60 Hz Emulation
Keywords: 60hz 50hz NTSC PAL Video
Message-ID: <1427@ethz.UUCP>
Date: 29 Jun 89 12:46:53 GMT
Reply-To: visinfo@bernina.UUCP (VISINFO Moderators)
Organization: ETH Zuerich, Switzerland
Lines: 39


60Hz emulation on PAL Amigas
****************************

Yes, it's true, you CAN produce 60Hz on "normal" PAL Amigas.
And moreover, you can have almost all the advantages of 60Hz on your PAL
(50Hz) Amiga: less flickering in noninterlaced mode, and an almost
acceptable picture in interlaced mode.

This fact again shows how brilliant the hardware of the Amiga was designed.
In fact, you can make the Amiga produce it's dispaly output at ANY vertical
blanking frequency between 50 and 60Hz and even out of this boundary.(I
have not yet had the opportunity to test this).

I found this trick some months ago and have since then improved the
technique so that it now works almost perfectly with AmigaDOS multitasking
and most of the high quality software. It has been tested in all graphics
modes, with the 2620 UNIX card, the GVP 68030 card, with the 2090, the GVP
impact and the AMIGA 1000 C-Ltd harddisk controllers on all of which it runs
perfectly.
Astonishingly, ALL monitors I have seen, like 1081, 1084, 1084S and all
non-standard-Amiga RGB monitors were able to work in 60 as well as in
50Hz mode and take less than 1 second to resynchronize. Most of them
(but not all) automatically stretch the image in order to make 200 lines
fill the same height as 256.

I have put it into a resident module so that I am now able to boot with
the NTSC configuration. But a lot of the tools like CED, DPaintIII, etc
even open their screens in the correct 200 lines size when the switch
to 60Hz has been made after the boot-up.

F. Buergel


/* -------------------------- SG (Simeon Graphics) ---------------------- */
/* Peter Simeon             |       //                             //     */
/* UUCP: ...visinfo@bernina |      //    Long live the AMIGA!     //      */
/* BIX:  hardwiz            |    \X/                            \X/       */
/* ---------------------------------------------------------------------- */