Short : HD Installer for Air Supply
Author: DJ Mike (djmike@crystalmike.com)
Version: 1.0
Type: game/patch
Requires: WHDLoad 19, RawDIC, 512k chip mem

This patch applies to "Air Supply" © 1990 Magic Bytes.

VERSIONS SUPPORTED

- Original release
- Cracked release by Galahad/Scoopex

REQUIREMENTS

- Original disk or compatible disk image
- RawDIC for the imager
- Slave requires WHDLoad 19+
- Game requires 512k chip memory
  (+ approx 700k other memory for preload option)

FEATURES

- Game loads fully from HD
- Uses real files, which can be compressed with Propack, CrunchMania or FImp
- Quit game at any time (default key F10), including on 68000 machines
- Highscores loaded and saved to disk
  (NOTE: Game requires you to press S to save highscores)
- Long track protection check removed
- Trace vector 'decrypt' routines removed (x8)
- Ports interrupt rewritten to fix keyboard handshake bug
- VertB interrupt clearing fixed for fast hardware
- Disk drive accesses removed
- Missing blitter wait fixed
- Extra blitter waits added to copper jumps to prevent copperlist corruption
- Stack pointer and decruncher moved to fast memory if available
- Game bug fix: Missing music due to copperlist ports interrupt switching
- Game bug fix: Access fault in bonus level due to invalid chip mem access
- Game bug fix: Level 8 now correctly loops to level 1, rather than 2
- Self-modifying code fixed for caching CPUs
- BltNasty setting disabled
- Trainer options added - set CUSTOM1 with any of the following:
  + 1 for infinite lives
  + 2 for infinite health
  + 4 for infinite fuel
  + 8 for infinite bombs
  + 16 for infinite supply units/crates
  + 32 to enable cheat keys (screen flashes blue for on, red for off):
    (There are limited keys available to use for these!)
    * TAB to toggle infinite lives
    * F4 to toggle infinite health
    * F5 to toggle infinite fuel
    * F7 to toggle infinite bombs
    * F8 to toggle infinite supply units/crates
    * DEL to skip current level (either main or bonus)
- Set CUSTOM2=1-8 to select starting level
- Set CUSTOM3=1-8 to increase health to x2/4/8/16/32/64/128/256
- CD32 controls supported, with two modes
  Set CUSTOM4=1 for Basic controls:
  * Blue - drop a supply unit/crate (replaces double-tap fire)
  * Green - use a smart bomb
  * Play+Forward+Reverse - quit game
  Set CUSTOM4=2 for Enhanced controls, which is Basic plus (on main levels):
  * Yellow - switch plane direction, and slow plane down
  * Right Shoulder - speed up
  * Left Shoulder - slow down
  To avoid confusing behaviour, double-tap of up/down or moving to edge of
  screen for controlling plane speed is disabled in this mode.
- Set BUTTONWAIT to wait for fire button on Magic Bytes logo,
  and press Escape to exit the "Space Invaders" minigame
- Color/New/Rom Icons included
- Source code included

HISTORY

Version 1.0 (2024-09-23)
- Initial release

WORDS FROM THE AUTHOR

I started out on this patch out of mild curiosity, but what an epic patch it
turned into! The protection was trivial compared to the litany of other
problems I've had to fix. For my trouble, I decided to add a bunch of extra
features too.

The original disk is Atari ST format, but unusually is 11 sectors per track
instead of 10. Every executable is "encrypted" with a simple xor cipher, but
the decryption code is hidden behind another encrypted layer obfuscated by
a trace vector routine very much like Rob Northen Copylock - i.e. decrypting
each instruction to execute, then re-encrypting after. Ultimately all of
that was more tedious to sort out than challenging. The useful xor cipher
code is now part of the patch to avoid any use of trace mode.

There is also a long 'protection' track, read before level 2, whose code can
be entirely skipped. I guess it's the thought that counts?

But good grief, the game itself was one pothole after another!

The music kept going silent when I was testing, due to a quirky switching on
and off of the ports/timer interrupt in the copperlist each frame. I've
removed this to try to make the patch more compatible, hopefully without
adding any slowdown.

The bonus level outright crashed with MMU enabled, because the game tries
to write to its screen buffer but gets the wrong address in the first frame,
and instead pokes the memory above 512k. Whoops! That took quite a bit of
digging to make a reasonable workaround.

Then there was self modifying code set by the game depending on whether you
are playing the game, or watching a replay. And a rogue BltNasty setting.
And the game didn't loop back from level 8 to 1 properly because it failed
to go back to side 0 of the disk. Doh!

And to further compound my misery, the game even managed to trip an obscure
Agnus hardware bug where, if the copper is waiting and the blitter is busy,
strobing copjmp1 will sometimes cause the blitter to corrupt the copperlist
instead of writing to its actual destination. That one was a real head-
scratcher until I happened to find a thread on the EAB forum documenting
the exact problem I was seeing!

Frankly, goodness knows if this game will ever work right on all setups!

So I decided to have some fun with it once I'd fixed all the bugs I found. 
The game is just ridiculously hard on its default settings, so I've added a
health multiplier to give you more of a fighting chance if you play without
cheating. You can set it to 2x normal health up to 256x (in powers of two).

I also changed up the controls entirely when supporting CD32 pads. The whole
double-tap to go faster/slower/switch direction was incredibly hard to play
with. Now you hit yellow to change direction, and use the shoulder buttons
to speed up/slow down. Blue drops supply units, and green sets off bombs.
Much less frustrating, hopefully. The only downside is that if you enable
these controls, replay mode will NOT work correctly, because the game no
longer knows how the controls work. If I'm feeling charitable in future I
might support that, but I don't think it's a big deal.

If you're so inclined, I've also added the a lot of trainers too. The usual 
infinite-everything trainers are there. Infinite health will keep you from
dying to everything including the boss. It took some figuring out but you
can also skip the current level too (either main or bonus).

Lastly, I discovered the game has a built in cheat mode!
(Although most of the features have been replicated by this install.)

In game, press T to activate cheat mode for the rest of the current level.
Then type any of the following:

HANK - Gives infinite supply crates 
DEDI - Makes you invulnerable to all enemies (including boss)
XTRA - Infinite time on weapon power-ups
BOMB - Gives you 50 bombs
NOBO - Skips the bonus level after completing the current level
FUEL - Infinite fuel
NEXT - On finishing the current level, advances +2 levels instead of 1
SEGA - Displays a floating SEGA logo over the screen
KILL - Kills the player (also removes invulnerable cheat)
MIRR - Mirrors half the play area
MISS - Spawns end of level boss
FRNY - Resets the cheats: infinite units, infinite weapon power-up time,
    skipping bonus level, infinite fuel, advance extra level, invulnerable
HELI - Shows some debug on the side of the screen

I hadn't intended it to be, but this patch became a passion project, if only
because I was determined to make it a bit more enjoyable to play than the
insane bullet hell it was on release!

Enjoy! :-)

--- DJ Mike (23rd September 2024)

         Bug report form, full WHDLoad package and other installs:
                          http://www.whdload.de

THIS PACKAGE COMES WITH ABSOLUTELY NO WARRANTY OF ANY KIND, EITHER EXPRESS
OR IMPLIED, STATUTORY OR OTHERWISE. THE ENTIRE RISK AS TO USE, RESULTS AND
PERFORMANCE OF THE PACKAGE IS ASSUMED BY YOU AND IF THE PACKAGE SHOULD PROVE
TO BE DEFECTIVE, YOU ASSUME THE ENTIRE COST OF ALL NECESSARY SERVICING,
REPAIR OR OTHER REMEDIATION.
UNDER NO CIRCUMSTANCES, CAN THE AUTHOR BE HELD RESPONSIBLE FOR ANY DAMAGE
CAUSED IN ANY USUAL, SPECIAL, OR ACCIDENTAL WAY, ALSO IF THE OWNER OR A
THIRD PARTY HAS BEEN POINTED AT SUCH POSSIBILITIES OF DAMAGE.