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Elite (Firebird, 1985)

 
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toinet
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Inscrit le: 15 Juin 2007
Messages: 3043
Localisation: Le Chesnay, France

MessagePosté le: Jeu 13 Sep 2007, 12:42    Sujet du message: Elite (Firebird, 1985) Répondre en citant

Elite is a well-known strategic space simulation (it is written on the box) edited by Firebird.

PROTECTION TYPE
It is a standard 16-sector disk with the following markers:
- Header: D5 AA 96 / DE AA
- Data : D5 AA xx / DE AA


THE PROTECTION
The disk uses a standard DOS and some tracks and sectors are copyable but some others are not. A BLOAD or a BRUN command calls a routine that updates the third data marker depending on the filename.

The pseudo-code is the following:
Code:

A <= GET LAST CHARACTER OF FILENAME
X <= GET INDEX OF LAST CHARACTER OF FILENAME
X <= X + (A AND #$1F)
$31 <= GET NIBBLE FROM AUTHORIZED NIBBLES,X


That is the first program I see using that kind of protection. It is a funny one.

Let's now get the marker related to the filenames:
Code:

E.LITE => index is 5, character is E, then data marker is BB
E.LA   => index is 3, character is A, then data marker is B4
S.EC3  => index is 4, character is 3, then data marker is DA



DISK COPY
There are several methods to copy the disk:
1/ Use a bit-copier to get an image of the protected disk
- Elite's disk is write protected, that will prevent you from making a hole on the disk
- Then edit T11/SF and rename the E.LITE file so that the DOS boot will jump to the prompt, allowing you to BLOAD the different files and copy them onto another disk.

2/ Use DiskFixer
- First of all, copy the disk with Locksmith. There will be read errors which are due to the change of marker
- Then launch DiskFixer, insert the original Elite disk on drive 1, the copy on drive 2
- Use the D command to display the directory and follow the different files described above
- Note that you will have to replace the third data marker with the Options menu
- Each sector read from the source drive must be copied to the second drive (option C)

3/ The easiest way
Just patch the data read routine of the RWTS:
- Launch Advanced Demuffin, go to the monitor
- B8FD: C9 AD D0 E7 => C9 AD D0 00
- CTRL-Y
- Copy the disk


COPY A NEW DOS 3.3
I have decided to replace the old DOS of Elite with an official version from Apple (thanks to Deckard for providing me with the original master disk):
- Launch Advanced Demuffin or Locksmith
- Copy the first three tracks (T0/S0 to T2/S4) from the Master disk to your copy of Elite
- Launch Copy II Plus 5.x
- Change the boot program of your Elite disk, it must be the E.LITE file

That's it! A funny one, it could have been differently (so many ways) but that was fun using different tools instead of doing it the easiest way!

Toinet
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