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1990-11-02
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6KB
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171 lines
** Requires a 1M Fatter Agnus to use **
This program is in the public domain. Meaning you can do whatever you
like with it. As a courtesy though, if you plan to modify or do something
interesting with it, I'd like to know, as I'm always interested in projects
of others.
PALCon v0.9 - PAL/NTSC Video Controller
---------------------------------------
Well, how many times have you booted up a Euro-Game or Demo and weren't
able to see the bottom of the screen because it was coded for PAL?
If your A2000 has the newer 1Meg Fatter Agnus chip in it, you are in luck!
PALCon will allow you to switch video modes and actually display a full
PAL resolution screen!
How to use
----------
Simply type PALCON from the CLI (or run it from Workbench if you like..
I haven't bothered to create an Icon for it..but it WILL start from
either CLI or Workbench). You should get:
PALCon - NTSC/PAL Video Controller v0.9
(c)1990 RomBase Productions - ICE9 9006.01
VSEG Installed.
>> RESET Amiga to Boot Up in PAL Mode <<
Now the next time you reset your machine, voila! You will boot up
in PAL mode!
Note: You may have to adjust your monitor so that the screen fits. If you
have a 1080 monitor, this is done by the little setscrews in the back.
The 1084 will automagically adjust itself.
More Details
------------
PALCon actually toggles between PAL and NTSC modes. It looks to see what
your machine is currently displaying and sets it up for the opposite mode.
In otherwords, if your machine is currently displaying NTSC, PALCon will
put it in PAL mode after reset. Likewise if you have your machine in
PAL mode, PALCon will reboot your machine in NTSC.
How it's Done
-------------
Previous Amigas required entirely different chips to determine whether they
operated in PAL or NTSC mode. Yet with the advent of the 1 Meg Fatter
Agnus chip, Commodore engineers added the ability to switch between
between the two modes. This was probably done to reduce costs (now only
1 set of chips needed instead of separate PAL and NTSC versions) and
thus simplify production.
The Hard Way
------------
An early article appeared in the C-A Developer's Newsletter describing a
hardware mod on the inside of the A2000 to give it this ability. If
you plan to leave your machine set permanently to PAL, this is probably
the way to go. I won't describe how to do it here. If you're really
serious about this and are reasonably competent with hardware hacking,
you'll find out how :-> Contact CATS (Commodore-Amiga Technical Support) or
call The Creative Edge (below).
The Softer Way
--------------
A similar solution to PALCon came from Europe in the form of the PALBoot.
This was a boot block type program that switched your machine to PAL when
booted with a PALBoot disk. The biggest problem with this is if you have
a harddrive. PALBoot does indeed kick a machine into PAL mode, but it
doesn't finish autoconfiguring other devices. Then too, this was only
one way. It allowed NTSC machines to switch to PAL, but not vice versa.
If you need PAL mode primarily for games (most of which are entirely
disk-based), (or you don't have a harddisk) PALBoot is ok.
(Selfish Motive: Because of a direct call to a ROM routine, PALBoot doesn't
work with a A2630 board in 030 mode. PALCon will.)
The Softest Way
---------------
PALCon goes in a different direction in that you boot your system as
normal. When PALCon is run, it installs a resident program in the system
ColdCapture vector. This little program is invoked upon a system reset,
and at this point switches your machine to PAL/NTSC, and finishes
booting the system. Thus you can still boot from your harddrive and
have any fast-ram autoconfigured.
(Note: Since this program does a somewhat *bad* thing by modifying a
system vector, some virus checkers (notably VirusX) may report a change
in the ColdCapture vector. This is NOT a virus, but the resident portion
of PALCon. Does this make you uncomfortable?
Solution = Reboot the system IMMEDIATELY after running PALCon..)
Incidently, if you try to run PALCon several times without rebooting,
(you run it say, twice in a row), it won't reload the resident switching
program. Instead, each time PALCon is run, it looks to see if there
is resident code present, if so, it merely updates the existing parameters.
Last stuffs
-----------
Well I hope this utility proves useful. I'm happy to see most developers
are providing support for PAL resolutions in their programs. Really, this
gives about 20% more screen area over NTSC..which is of course, very nice.
PALCon is little over 2100 bytes and is written in assembly using
the Devpac Assembler. Highly recommended for anyone who doesn't want to
grow old waiting for source code to assemble..
I'm sorry for the disarray of this doc file. PALCon and this doc was
hacked together in the past two hours and I seriously need to get to bed.
I'd greatly welcome any/all suggestions or input you have in regards to
this program.
- ICE9 (aka V. Yanagida)
9006.01
98-453-2 Kaonohi St.
Aiea, Hawaii 96701
or call:
The Creative Edge
(808) 487-6977
24 Hrs
300/1200/2400 Baud.
Late Notes
----------
1) I forgot to mention that this program has a faulty memory. In otherwords,
if you use it to switch to PAL, then reboot the machine again, it will
default back to it's 'native' video mode. I was working on trying to
get the resident portion of PALCon to survive subsequent resets better,
but haven't quite finished. It was supposed to keep the resident portion
in memory always and only change modes when told to. (This is why
this version is 0.9)
2) From what I hear, the A3000(!) and Workbench 2.0 will have a setting in
Preferences to select between PAL and NTSC, thus rendering this program
obsolete. It's just that I don't want to have to wait until fall of 1990
(expected WB2.0 release date) for this...