[alt.sources.amiga] INFO-- Why some demos crash!

kskelm@happy.colorado.edu (02/28/91)

In article <1991Feb26.204825.17757@hoss.unl.edu>, 231b3678@fergvax.unl.edu (Phil Dietz) writes:
> One demo that I REALLY want to see is the Phantasmagoria one.  The one
> posted on AB20 crashes right when it starts to get good...does anyone have
> a DECENT copy?

  I've found that nearly *ALL* of the demos I've downloaded run perfectly when
the computer is running in PAL mode.

  There's a program out called PalBoot that puts machines with the ECS into PAL
mode-- in fact, I permanently have my screen scrunched (pot in back) to
accomodate the higher resolution of PAL.  Unfortunately, the PalBoot program is
rather unflexible.  Since many ST/NT songs are written for PAL and others are
written for NTSC, I whipped up a couple of simple programs, PAL and NTSC.

   You can, too...  To put the machine in PAL mode, simply plug the value #$20
into location $DFF1DA (LONG WORD!!!!!!).  To put it back into NTSC mode, insert
a value of #$02 I believe (Once again, a LONGWORD!).


  ...Its also nice to be able to see the scrollies! :-)

         Kevin Kelm

SIG withheld by request

chem194@csc.canterbury.ac.nz (John Davis) (02/28/91)

>   There's a program out called PalBoot that puts machines with the ECS into PAL
> mode-- in fact, I permanently have my screen scrunched (pot in back) to
> accomodate the higher resolution of PAL.  Unfortunately, the PalBoot program is
> rather unflexible.  Since many ST/NT songs are written for PAL and others are
> written for NTSC, I whipped up a couple of simple programs, PAL and NTSC.
> 
>    You can, too...  To put the machine in PAL mode, simply plug the value #$20
> into location $DFF1DA (LONG WORD!!!!!!).  To put it back into NTSC mode, insert
> a value of #$02 I believe (Once again, a LONGWORD!).

The trouble with just dumping $0020 or $0000 into $dff1dc is that whilst
the hardware changes over (i.e you'll get the frame rate etc changing)
the actual system copperlists don't get modified to match. This can
result in some interesting effects....
 
I've tried hacking around to get the copperlists, lib vars etc updated,
but had no real sucess (guess we'll just have to wait for wb2.0 for on
the fly ntsc/pal :-) - in the meantime the best you can do is select screen
modes at boot time - to facilitate this I knocked up a program by the
name of BootMenu (which you can find in /incoming/amiga on
abcfd20.larc.nasa.gov) which allows _user_selectable (via a menu) choice
of screen modes at every reboot (it wedges itself into the system). That
means that once you've loaded it, you can reboot at any time and re-choose
NTSC/PAL (unlike PalBoot where you've got to run it each time you want to go
PAL - a real pain).

Also it works properly with 030's etc - and it even gives you the choice
of turning of your hard-disks  to protect against 'rogue programs'.
 
Of course if you want to do it properly, wire up a toggle switch on the
appropriate line to the 1mb agnus and switch it in hardware (that way
you can _permanently_ select the screen mode of your chosing)

-----------------------------------------------------------
| o  John Davis - CHEM194@canterbury.ac.nz               o |
| o  (Depart)mental Programmer,Chemistry Department      o |
| o  University of Canterbury, Christchurch, New Zealand o | 
| o                                                      o |
| o  co-sysop AmigaINFO BBS,1200/2400 baud CCITT,        o |
| o           24 hours a day, ph NZ +3-3371-531          o |

peter@sugar.hackercorp.com (Peter da Silva) (02/28/91)

This stuff would be quite appropriate in comp.sys.amiga.something, and would get
better distribution. Why carry on a discussion here?

Just wondering...
-- 
Peter da Silva.   `-_-'
<peter@sugar.hackercorp.com>.

ceej@mole.ai.mit.edu (Chris Hillery) (03/02/91)

Has anyone come up with a usable way to put a non-1MB Agnus-equipped Amiga
into PAL mode?  At least in terms of screen resolution... I understand as
how changing the sync rate (if Agnus does indeed do that too) would be a 
tad tough in software.  There's just so many things I'd like to be able to
see fully on the screen...

Ceej
aka Chris Hillery
ceej@rpi.edu