Path: utzoo!attcan!uunet!lll-winken!ames!pasteur!ucbvax!TRINCC.BITNET!REWING
From: REWING@TRINCC.BITNET
Newsgroups: comp.sys.apple
Subject: Re: Flight Simulator Scenery Disks
Message-ID: <8904051455.aa19349@SMOKE.BRL.MIL>
Date: 5 Apr 89 18:14:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 50

I think I can shed a little light on the 3.5 inch disk problem from
SubLogic's standpoint regarding scenery disks.

Back in 1985, one of my last, and probably greatest software cracks was
SubLogic's Flight Simulator ][.  At the time, it was one of the most
brutal programs to copy, as you had to open up your disk ][ and slow
the drive speed down considerably to make a good copy.  To make matters
worse, a normal 5.25" disk, whether DOS or ProDOS has 35 tracks, 16 sectors
per track.  Flight Simulator instead had a scheme in which every track
past track 0 had one *BIG* secto, which was worth 16 sectors.  Whenever
the program did some disk access, it would switch the video to the second
Hires screen bank, and then use the memory of the first bank to load
in that entire sector ($2000-$35FF in memory).  Once read it, it would
take the information in big 4 sector chunks and do memory moves to whereever
the info was needed.  Of course, this leaves one thing unresolved: if
you remove all the gaps that seperated the 16 sectors and combined them
into 1, where does the extra gap space go?  Well, ever noticed how long
it takes for FSII to boot up on a 64K or better machine? (Seeming like
its reading every track?)  In fact, it is reading every track.  They
got very sneaky and used the extra space left over on ever track to throw
on a small piece of 4x4 encoded data.  When all the data was read in,
it was worth 16K, just enough the fill the language card segment, and
thus managing to get 160K+16K=176K of storage on a standard Apple II disk.
Sneaky, huh?  How do you crack a program that has more data on it than
a standard copyable disk?

It turned out that not all of the master disk was full of scenery data.
The empty sectors were wiped clean with the byte $FE, so I wrote a little
routine to load the language card from these sectors which I preloaded
the 16K RAM software, then continued the standard loading process.
Then I threw out all the read/write routines, replaced them with standard
ones based on DOS 3.3 RWTS, and got them to work with FSII memeory management
routines.  Finally, I added a FSII Scenery disk conversion program
that was loaded onto the empty space on track 0 (I had two *bytes* left
on track 0 once that was finished, *whew*!)

To sum this all up, FSII's disk read/write routines arecompletely tied
to the Apple Disk II 5.25 format.  For SubLogic to try to support 3.5"
would be almost impossible considering the constraints of the program,
lack of RAM memory of disk space for the routines, age of the software,
and many other factors.  Hopefully, if and when SubLogic releases
FSIII for the Apple IIgs, it will be in a copyable 3.5 inch format,
GS/OS compatible.  Alas, we can always dream...

--Rick Ewing
  Now earning a respectable career a Apple Computer
  Atlanta Georgia

P.S.  If any of you still have that FSII crack, I went under the name of the
Byte Busters!