visinfo@ethz.UUCP (VISINFO Moderators) (06/29/89)
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/ */ /* ---------------------------------------------------------------------- */
athomson@ayov10.dec.com (Alan Thomson) (07/01/89)
In article <1427@ethz.UUCP>, visinfo@ethz.UUCP (VISINFO Moderators) writes... >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. [stuff deleted] HOW ?? Tell me more, where do I send my money ?? who do I have to kill ?? I would give a lot to have 60Hz (30Hz) flicker in interlace rather than the 50Hz (25Hz) I have now. A question though.. In 60Hz mode, how close can you get back to the PAL screen size ? (Using morerows or whatever) >/* -------------------------- SG (Simeon Graphics) ---------------------- */ >/* Peter Simeon | // // */ >/* UUCP: ...visinfo@bernina | // Long live the AMIGA! // */ >/* BIX: hardwiz | \X/ \X/ */ >/* ---------------------------------------------------------------------- */ ------ All opinions are mine and do not..... etc. --------------------- | Amigas have 4097 colours, | | Alan Thomson | | the last being Octarine - | | Digital Equipment Corp. | | the colour of MAGIC !! | | Ayr, Scotland. | athomson%ayov10.dec@decwrl.dec.com
visinfo@ethz.UUCP (VISINFO Moderators) (07/05/89)
In article <3303@shlump.dec.com> athomson@ayov10.dec.com (Alan Thomson) writes: >In article <1427@ethz.UUCP>, visinfo@ethz.UUCP (VISINFO Moderators) writes... > >>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. >HOW ?? Tell me more, where do I send my money ?? who do I have to kill ?? >I would give a lot to have 60Hz (30Hz) flicker in interlace rather than >the 50Hz (25Hz) I have now. I plan to release the 60Hz Emulator as one module in a resident utility I am working at presently. This way you can switch 50/60 at ANY time and the status survives reboot. However, the PowerUtility is not yet finished entirely. Also, I have not yet found a convenient way to distribute it. Hope you can get it before the end of '89... or earlier! >A question though.. In 60Hz mode, how close can you get back to the PAL >screen size ? (Using morerows or whatever) Physically, you have 313 screen lines in 50Hz mode and 261 in 60Hz. The standard screen size as used by AmigaDOS is 256 lines for 50Hz and 200 lines for 60Hz. The maximum number of usable vertical lines incl. overscan is about 280 in 50Hz and 230 in 60Hz. Therefore it is impossible to get the original PAL screen size in 60Hz. However, you can MIX PAL and NTSC screens the following way: You boot up with 50Hz and get a PAL Workbench, you load all utilities you want to bring up PAL screens, switch to 60 and continue work. This way, you really have all the advantages of both modes. F. Buergel /* -------------------------- SG (Simeon Graphics) ---------------------- */ /* Peter Simeon | // // */ /* UUCP: ...visinfo@bernina | // Long live the AMIGA! // */ /* BIX: hardwiz | \X/ \X/ */ /* ---------------------------------------------------------------------- */
visinfo@ethz.UUCP (VISINFO Moderators) (07/06/89)
Discussion: 60Hz on PAL Amigas
******************************
A number of people have asked questions about the 60Hz emulation. Here are
the answers to some of the most interesting questions:
Question 1:
If 60Hz can be done, and the range is not limited, so shouldn't let's say
70Hz also be possible?
Answer:
Yes, 70Hz is possible, by principle. However there is not a very large
advantage in it, because
1) you have a further loss of vertical resolution,
2) software would not support this and
3) I'm not sure if Amiga monitors in USA can cope with that frequency
(in Europe, the 1081/1084 stop at 64Hz).
Question 2:
If the Amiga can be made send it's dispaly output at any VB frequency,
so why don't we get a "PAL 50Hz emulator", too?
Answer:
OK. Why not. My only problem is that I do not have an NTSC/60Hz system,
which makes it difficult for me to develop and test such a thing.
Also, I'm afraid some problems could come up that aren't there in the
other "direction". Namely: Maybe Sprites don't appear exactly the right
way in the extra portion of the screen. But let's not give up hope yet.
I still have an old NTSC Agnus for my AMIGA1000 somewhere. Because many
people showed interest in a PAL/50Hz emulation, I'm going to unscrew the
old lady to be able to check that out.
Question 3:
Can we get more resolution by setting the VB rate below 50Hz?
Answer:
No, not really. Basically yes, but it's almost impossible to make it work
correctly with AmigaDOS (I'm not a specialist when it comes to graphics-
library and intuition hacking, so maybe I'm wrong to say this.)
You could make a low-level programmed application which runs in 45Hz mode
and then has a usable area of about 300 noninterlaced lines in the vertical
direction.
However, the same problem as explained in answer #2 could appear:
Bitplanes work fine, but sprites get confused in the extra portion of the
screen. Also, this kind of display is not likely to work with most
common monitors, not even multisync type ones.
F. BURGEL
/* -------------------------- SG (Simeon Graphics) ---------------------- */
/* Peter Simeon | // // */
/* UUCP: ...visinfo@bernina | // Long live the AMIGA! // */
/* BIX: hardwiz | \X/ \X/ */
/* ---------------------------------------------------------------------- */