Leather goddesses of Phobos (Infocom, 1992)

[toinet]

A sex-oriented text adventure by Infocom. You'd better speak and understand English (and slang English) very well otherwise you'll get lost quite rapidly. At the time of HackerForce, the game has been distributed with its on-disk protection!


PROTECTION TYPE
On a double-sided diskette, you have:
- a standard 16 sectors disk on side 1
- a special 18 sectors disk on side 2!


BOOT TRACE
As usual:
- 9600<C600.C6FFM
- 96FB: AD E8 C0 60
- 9600G
Bing! The code at $0801 loads next sector at $0900 and then loads the other sectors from $D000 to $DFFF. It ends with a JSR $D505 and JMP $DD48.

We would like to get the data loaded somewhere else:
- 96FB: A9 10 8D 0C 08 A9 4C 8D 3F 08 A9 59 8D 40 08 A9 FF 8D 41 08 4C 01 08
- 9600G
Bing! We now have the next boot process beginning at $1000

The interleaving is set as the following table:
- 00 04 08 0C 01 05 09 0D 02 06 0A 0E 03 07 0B 0F


THE RWTS ADDRESSES
After a code disassembly, we get:
- $D000: RWTS main entry
- $D010: nibblize 256 bytes to 342 6*2 coded nibbles
- $D03A: write sector
- $D0D2: denibblize 342 6*2 coded nibbles to X bytes (X is set at $0D)
- $D154: read header marker and data (volume/track/sector)
- $D1B0: move arm
- $D2E0: the RWTS management routine
- ...: other routines
- $D486: read a 18-sector from disk
- $D505: some inits
- $D51D: translation routine
==> Given two parameters (maybe a page index), the routines translates the values into a track and sector value depending on the side (side 1 = 16 sectors per track, side 2 = 18 sectors per track)
- $D871: please insert side 1 of the disk routine
==> $EB = 1
- $D8A1: please insert side 2 of the disk routine
==> $EB = 2
- $DD48: the main program loop

That is a huge RWTS, using lots of parameters in the zero page. What was fun to discover is the ADC #$12 or SBC #$12 making me understand that the second side was a 18-sector one. There have been several games using that kind of protection: Flight Simulator 2, Wings of Fury, Prince of Persia and maybe others. It appears that the disk scheme was sometimes different. Let's see ours.


A 18-SECTOR TRACK
A track from that game is seen as a header followed by a set of 18 * 343 (342 + 1 as a checksum) nibbles with no separators between each of them.

We therefore have:
- D5 AA AD: the header marker
- XX XX: two nibbles coding the track number
- ...: 343 nibbles (342 +1 as a checksum) for sector 0
- ...: 343 nibbles (342 +1 as a checksum) for sector 1
- and so on...


THE RWTS COMMANDS
As it is a non-standard disk nor crack, I will detail the different commands of the RWTS:

The format of the call is:

[Deckard]

Attention pour les softs Infocom, il y a souvent plusieurs versions d'un m�me titre qui sont sorties avec des ann�es d'�cart.

=> Qui dit version diff�rente, dit aussi d�protection probablement dissemblable.

Il faut pr�ciser ici qu'il s'agit de la version SOLID GOLD (il y a du dor� sur la jacquette du programme) et cette version a 2 faces contrairement � la version initiale sortie quelques ann�es plus t�t qui n'en comptait qu'une seule. (Si le programme vous demande de retourner le disk, vous avez la derni�re version). Ce suppl�ment correspond � une aide en ligne -built-in hint menu (qui prend de la place).

Il est aussi possible de se rep�rer par rapport � la version de l'interpr�teur Z-Machine (num�ro � rajouter - l� je ne peux pas, je suis sur le d�part en cong�s). Ce num�ro s'affiche au d�marrage.

JM

[Deckard]

Je suis tr�s �tonn� que cette version date de 1992
J'aurais plut�t dit la fin des ann�es 80.
JM