Here is a summary of the previous changes made to Genesis Plus



  • corrected TeamPlayer support: fix multiplayer in Gauntlet 4 (Sept. version), Pengo and a lot of others
  • added J-Cart support: enable multiplayer in Codemasters games (Pete Sampras, Micromachines games, Super Skidmarks)
  • added serial EEPROM autodetection: fix games with bad SRAM informations in header (NBA Jam TE)
  • added SVP faking: display 2D graphics in Virtua Racing (the game is however still unplayable)
  • added support for more internal IO registers: fixe some unlicensed games (Wisdom Tree games…)
  • added preliminary support for unmapped protection device: fix some unlicensed games with special built-in hardware (Squirell King, Lion King 2…)
  • added “Soft Reset” combo (in game, use L+Z triggers): this should be like pressing the RESET button on a real Genesis and this is required in some games to enable special features or even complete the game (ex: X-Men).


  • added separate configuration for PortA/PortB inputs (GAMEPAD, MULTITAP or NONE, see Joypad Config): this let you setting PORTB as unplugged, which is needed in some games to access special modes or enable cheat codes (Alien Storm, X-Men…)
  • Freezestate & SRAM files are now compressed (using zlib)
  • FreezeState & SRAM files can now be saved/loaded to/from SDCARD: located in /genplus/saves/ from the root of your SDCARD
  • changed initial ROMS directory for SDCARD user: now looking for /genplus/roms/ from the root of your SDCARD
  • added user-transparent SRAM autoload (detection order is MCARD then SDCARD, SLOTA then SLOTB)
  • “System reboot” is now used for console reboot or SD/PSO reload if detected
  • added new font: now use original IPL font, extracted from Bootrom
  • modified controls when going into the rom selection menu (DVD or SDCARD):
    • use B button to go up one directory
    • use Z button to quit the file selection menu
    • use L/R triggers to go down/up one full page
    • use Left/Right buttons or Analog stick to scroll the selected entry’s filename when it can’t be full displayed
  • various menu rearrangment, minor bugfixes & sourcecode cleanup


  • added 4.7GB DVD support for WII drives (the maximal allowed size for Gamecube DVD is still 1.35GB)
  • removed MPAL video timings, always use 60Hz NTSC: fix display problems for PAL wii users (no more PAL50 version needed)
  • added Console Reboot option in main menu (IPL Reboot)
  • added Multitap support (EA 4-Way Play and Sega Teamplayer): allowed up to four players in games supporting those peripherals
  • added partial Sega Menacer lightgun support (use Analog Stick): automatically set when detecting the 6-in-1 Menacer game


  • you can now switch between FM cores without reseting the game. FM registers value are automatically restored when switching.
  • modified PAL framesync a little bit: the 20ms period is now applied between the start of 2 consecutive frames, no more between the end of the previous and the start of the next one, which seems more correct to me.
  • removed the previous VINT timings modification because it brokes some games (Rocket Knight, Thunderforce III,…)
  • added automatic Timing configuration (VDP latency, VINT timing & alternate Line Timing) at game loading, based upon specific romname detection. This means you can still modify some of these options afterwards but they are now automatically set/unset when loading a game which need special timing fixes. These fixes are also automatically desactivated when the current game doesn’t need them. For your information, games that are actually detected and need special timings to run properly are:
    • Legend of Galahad & Road Rash series (single line not rendered properly)
    • Sesame Street Counting Cafe (don’t boot)
    • Chaos Engine/Soldiers of Fortune (graphic glitches on scrolling)


  • corrected L & R buttons assignment: fixes Genesis X & Z buttons being inverted
  • VINT timings are now a little more accurate: fixes Sesame’s Street Counting Cafe
  • SN76496 MAX_OUTPUT back to normal
  • modified FB_WNOISE value in SN76496 core according to John Kortink’s last informations
  • added support for Maxim’s PSG core, same as used in SMSPLUS (it becomes the default PSG core)
  • updated FM core to the latest MAME version
  • corrected DAC output level (fixes voices and some special FX being too low)
  • added support for Gens YM2612 (FM) core (MAME’s one still remains default FM core)
  • added configurable preamplification for each sound cores (see Sound Options)
  • added some other configurable sound options (boost overall volume, FM improvment for Gens YM2612)


  • corrected MAX_OUTPUT value in SN76496 core: fix PSG sound (SFX) volume
  • removed unused sound buffer allocation


  • added DVD automount: automatically call libogc DVD_Mount function if ISO PVD reading failed (idea taken from softdev’s last neocdredux release). This may be useful for loading roms from a DVD after booting from SDLOAD or after stopping DVD motor.
  • added “DVD motor off” feature, like in others emulators
  • corrected Memory Card mounting function: EXI_ProbeReset() function was never called if the first mounting attempt failed. Should fix some of the “Unable to mount memory card” errors.


  • added SDCARD subdirectory browsing and LFN (255 char. max) support


  • remove some rendering unused code (only used by DOS version of genesis plus) for little speedup
  • added an option to enable alternate line rendering timing (fix single line error in Road Rash series and Legend of Galahad’s Intro)
  • Color RAM update now always reset color 0 to border color (fix color glitches in Mortal Kombat,…) (thanks to Nop’s for the idea)
  • added last Softdev’s modifications (normalised memory access and ASM GU functions used intead of ‘C’ ones) for some speedup
  • updated gcaram.c to be compatible with last libogc version


  • little rendering code speedups
  • modified HV counter tables (fix graphic glitches in Skitchin’s sky, Lotus 2 Recs, Panorama Cotton, Dashin Desperados & maybe more)
  • completely rewrote DMA timings emulation so that it works for all games (no more cpu freezing)
  • added all DMA tranfer rates handling for each three DMA modes and added dma busy flag emulation
  • modified interrupts handling on VDP register #0 and #1 writes (fix Lemmings status bar)
  • added VDP RAM write latency (fix Chaos Engine/Soldier of Fortune gfx glitches)
  • modified FM timers handling a little bit (fix Vectorman2 music)
  • corrected Sprite Limit rendering (fix Sonic 1 & Micromachines 2 title screens)
  • corrected IO Registers writes (fix Decap’ Attack controls, no more need for alternate input)
  • corrected 6 Buttons Pad emulation (fix 6buttons detection in Mortal Kombat 3, Comix Zone and other 6-buttons compatible games)
  • modified sound mixing a bit according to Generator sourcecode (FM and PSG ratios seems more correct)
  • added separate CPU Region (USA, Europe, Japan,…) & Speed (PAL or NTSC) choice in menu options
  • modified main frame synchro in PAL mode (fix sound glitch in this mode), thanks to Softdev for the solution
  • added savestates support


  • added correct FM Timers emulation (fix missing music in Castle of Illusion, Quackshot, Undead Line, Wonderboy in Monster Lair, Cal 50, Turbo Outrun, Thundeforce 4 and certainly more)
  • added partial EEPROM emulation, used by few games as backup RAM: SRAM support now works fine in Wonderboy5, Megaman Willy Wars, NBA Jam… (credits to Notaz, adapted from Picodrive code)
  • added preliminar dma timing emulation (fix bottom screen in Legend of Galahad) (credits to Notaz, adapted from Picodrive code)
  • hack: clear Vint pending after Hint (INT level 4) acknowledge (fix Fatal Rewind)
  • hack: modify read_bus16 to return a random value (fake fetch) (fix Time Killers)
  • modified cpu execution timings, with more correct hblank and interrupts timing (fix ISS Deluxe, Double Dragon 2 and certainly more) (Based on Gens code)
  • modified busreq mechanism: better synchro between z80 & 68k (no need to dejitter anymore) (Based on Gens code)
  • added sprite collision detection (fix Strider 2)
  • modified dma fill operation for big endian platform(fix Contra Hardcorps gfx garbage)

Softdev’s initial releases (some WIP changes are missing)


  • Added partial zip support


  • Added six button pad support from x86 Gens
  • Additional changes based on Charles MacDonald’s gen-hw.txt

WIP1    07 March 2006

  • Updated SN76496 driver
  • Added GX Hardware Scaling