GenEm   SEGA Genesis/SEGA Mega Drive  Emulator

                        version 0.19 PUBLIC BETA

                     (c) 1996,1997 by Markus Gietzen

+---------------------------------------------------------------------------+
  MS-DOS Version:

     +486 or higher (386 doesn't work, speedy Pentium recommended)
     +4MB RAM       (8MB highly recommended; 16MB if you use it under Win95)
     +SoundBlaster with _OPL3_ (OPL2 doesn't work !)
+---------------------------------------------------------------------------+


E-Mail:      iig05-1@htw.uni-sb.de      (READ THIS FILE _BEFORE_
             magi@stud.uni-sb.de         YOU WRITE ME!)

WWW:         http://myst.slcc.edu/~markus

Snail-Mail:  Markus Gietzen
             Ludweilerstr. 126
             66352 Grossrosseln
             GERMANY

0. _BEFORE_ you write me:

o Please note that I can't provide you with ROMs nor with URLs where
  to get ROMs from !!

o Please don't send me larger files without asking me first. Thanks !

o Read the FAQ !  Thanks.


1. DISCLAIMER

  I exclude any and all implied warranties, including warranties of
fitness for a particular purpose. I make no warranty or representation,
either express or implied, with respect to GenEm, its quality, performance
or fitness for a particular purpose.
I shall have no liability for special, incidental, or consequential damages
arising out of or resulting from the use, misuse, or modification of GenEm.

  All trademarks used in this documentation are property of their respective
owners.

2. Copyright / License

GenEm is (c) 1996,1997 by Markus Gietzen
The Z80-emulation is (c) 1994,1995,1996,1997 by Marat Fayzullin and
included with his permission (thanks again !).

GenEm is freeware for non-commercial purposes.
This means that you can use GenEm for free as long as you use it for your
_personal_ enjoyment. Anyway I'm pleased with any gift that I get.

Commercial purposes mean that you offer GenEm for money or you
offer GenEm because of PR-reasons (PR=public relations).

!! CD-collections that are sold at a reasonable price (<=$20) !!
!! can include GenEm for free _if_ it's sold by a private.    !!
!! Companies _always_ need to contact me first (even if you   !!
!! give it away for free!)                                    !!

3. Changes/Known problems:

  Please read the file "CHGLOG" for changes that have been made.

 Known problems:
  o priority-handling is sometimes not correct
  o "Window" is missing (no score-display in several games)
  o most ECA-games fail.
    -> Press START as soon as the ECA-logo appears (this skips the ECA-intro).
  o smaller bugs in the DMA-handling
  o bugs in HBLANK-IRQ -> problems in racing games


4. Usage

Usage:  genem [-options] rom-image

Options:
-frame  x   - display every x.th frame (2=default)
-nosound    - disable sound
-nojoy      - disable PC-joypad support
-modex      - enable 320x240 resolution
-calib      - start calibration-tool
-z80        - ENABLE Z80-emulation
-fakedz80   - FAKE Z80-emulation
-europe     - European version   |\  USA is
-japan      - Japanease version  |/  default.

Supported file-formats:
 o .bin         binary dumps
 o .md, .mgd    Multi Game Doctor II
 o .smd         Super Magic Drive

Keys:
   cursor-keys     -    direction-select
   ENTER           -    start-button
   A               -    button A
   B or S          -    button B
   C or D          -    button C
   TAB             -    reset
   ESC             -    power-off
   F1              -    start-button for Player 1
   F2              -    start-button for Player 2

Please don't create your own file-extensions ! GenEm fails if it can't
determine a supported file-extension (an autodetect in an earlier
version failed because of some non-Sega-compliant ROM-headers).

If the emulation is too slow for you then try to skip several frames.
The speed-increase is not linear because the gfx-render is quite fast
but the 68k-engine is still slow.
Try to use "gennew.exe" instead of "genem.exe". 


Battery-backed RAM:
  I think an example is the best way to show how this work:

      genem images\phstar2.bin

  Your RAM-contents are saved as "images\phstar2.sav" here.
  When you play phstar2.bin the next time these contents are
  loaded.
  Normally you don't have to care about that. Everything works
  like with a real cartridge. The only exception is: you load
  the game from a read-only medium (e.g. CD-ROM). Then it's not possible
  to save the RAM-contents.

5. genem.exe <-> gennew.exe

Since 0.17 there are two versions of GenEm. Genem.exe uses a slower M68k
engine (written in C) and gennew.exe uses a fast but still buggy M68k
engine (written in 100% assembly).

Warning: Due to the nature of the bug in gennew.exe it can happen that
         .SAV files (contents of backed up RAMs) will be destroyed.
         Therefore it's a good idea to backup your .SAV file before
         you try gennew.exe. Of course this only affects games that
         have backed-up RAM (e.g. Phantasy Star series).