Editing Picodrive

Picodrive is a Sega Genesis and Mega CD emulator developed by Notaz. It has the ability to emulate Sega CD, Sega Genesis, and Megadrive images. Picodrive's code has been based on fdave's Picodrive v0.30 for PocketPC, and from Stephane Dallongeville's Gens. The current version is 1.51 released on July 18, 2008.

==Features==

Picodrive has various features where a numerous amount of different configurations can be used to emulate any one image file. These include render options, and some other emulator specifc images.

===Render Modes===

===Region Faking===

This forces the image that is being ran to think it comes from a specific region. (US, Europe, or Japan) This is a emulator-wide effect and affects all iamges played.

===Savestates===

Self-explantory. Allows for savestates and slot support for any image. Also, savestates can be saved and loaded on the fly during emulation.

===Overclocking===

Like most emulators, Picodrive allows for manual overclocks of the PSP up to its max of 333 MhZ.

===Specifc Settings Saves===

Picodrive allows for specific config files to be saved for any image that will be loaded up when that particular image is loaded.

===Cheats===

Only GameGenie and Genecyst patches are supported by Picodrive and they must be imported via a patch file. (.txt file with extension renamed to .pat) With either a GameGenie or Genecyst cheat per line, it can be applied to any image depending on how the path file is renamed. The cheats are loaded as any other ROM, and the cheat menu will be loaded.

==Changelog==

'''1.51'''
  * Improved bin_to_cso_mp3 tool, it should no longer complain about
    missing lame.exe even if it's in working dir.
  * Fixed a regression from 1.50, which caused slowdowns in Final Fight.
  * Fixed some regressions from 1.50 related to sprite limit and palette
    handling (caused graphical glitches in some games).
  + Added ABC turbo actions to key config.
  * Some other minor adjustments.

'''1.50'''
  + Added some basic support for Sega Pico, a MegaDrive-based toy.
  + Added proper support for cue/bin images, including cdda playback.
    .cue sheets with iso/cso/mp3/wav files listed in them are now
    supported too (but 44kHz restriction still applies).
  + Added bin_to_cso_mp3 tool, based on Exophase's bin_to_iso_ogg.
    The tool can convert .cue/.bin Sega CD images to .cso/.mp3.
  * Greatly improved Sega CD load times.
  * Changed how scheduling between 68k and z80 is handled. Improves
    performance for some games. Credits to Lordus for the idea.
  * YM2612 state was not 100% saved, this should be better now.
  * Improved renderer performance for shadow/hilight mode.
  * Added a hack for YM2612 frequency overflow issue (bleep noises
    in Shaq Fu, Spider-Man - The Animated Series (intro music), etc.)
    Credits to Nemesis @ spritesmind forum. Works only if sound rate
    is set to 44kHz.
  + Implemented some sprite rendering improvements, as suggested by
    Exophase. Games with lots of sprites now perform better.
  + Added better idle loop detection, based on Lordus' idea again.
  - "accurate timing" option removed, as disabling it no longer
    improves performance.
  - "accurate sprites" was removed too, the new sprite code can
    properly handle sprite priorities in all cases.
  * Timers adjusted again.
  * Improved .smd detection code.
  * ARM: fixed a bug in DrZ80 core, which could cause problems in
    some rare cases.
  * ARM: fixed a problem of occasional clicks on MP3 music start.
  * Minor general optimizations and menu improvements.
  * Fixed a bug in Sega CD savestate loader, where the game would
    sometimes crash after load.
  * Fixed a crash of games using eeprom (introduced in 1.40b).
  * PSP: fixed suspend/resume (hopefully for real).

'''1.40c'''
  * Fixed a problem with sound in Marble Madness.
  * GP2X: Fixed minor problem with key config.

'''1.40b'''
  * Fixed sprite masking code. Thanks to Lordus for explaining how it works.
  + Added "disable sprite limit" option.
  + PSP: added black level adjustment to display options.
  * Changed reset to act as 'soft' reset.
  + Added detection for Puggsy (it doesn't really have sram).
  * Some small timing adjustments.

'''1.40a'''
  * GP2X: Fixed a binding problem with up and down keys.
  * Default game config no longer overrides global user config.

'''1.40'''
  + Added support for SVP (Sega Virtua Processor) to emulate Virtua Racing,
    wrote ARM recompiler and some HLE code for VR. Credits to Exophase and
    Rokas for various ideas.
  * Changed config file format, files are now human-readable. Game specific
    configs are now held in single file (but old game config files are still
    read when new one is missing).
  * Fixed a bug where some key combos didn't work as expected.
  * Fixed a regression in renderer (ARM ports only, some graphic glitches in
    rare cases).
  * Adjusted fast renderer to work with more games, including VR.
  * Fixed a problem where SegaCD RAM cart data was getting lost on reset.
  * GP2X: Greatly reduced SegaCD FMV game slowdowns by disabling read-ahead
    in the Linux kernel and C library (thanks to Rokas and Exophase for ideas
    again). Be sure to keep "ReadAhead buffer" OFF to avoid slowdowns.
  + PicoDrive now comes with a game config file for some games which need
    special settings, so they should now work out-of-the-box. More games will
    be added with later updates.
  + GP2X: Files now can be deleted by pressing A+SELECT in the file browser.

'''1.35b'''
  * PSP: mp3 code should no longer fail on 1.5 firmware.
  + PSP: added gamma adjustment option.
  + Added .cso ISO format support. Useful for non-FMV games.
  * It is now possile to force a region after the ROM is loaded.
  * Fixed a sram bug in memhandlers (fixes Shining in the Darkness saves).
  * PSP: fixed another bug in memhanlers, which crashed the emu for some games
    (like NBA Jam and NHL 9x).
  + PSP: added suspend/resume handling for Sega CD games.
  + GP2X: added additional low volume levels for my late-night gaming sessions
    (in stereo mode only).
  + GP2X: added "fast forward" action in key config. Not recommended to use for
    Sega CD, may case problems there.
  * Some other small tweaks I forgot about.

'''1.35a'''
  * PSP: fixed a bug which prevented to load any ROMs after testing the BIOS.
  * PSP: fixed incorrect CZ80 memory map setup, which caused Z80 crashes and
    graphics corruption in EU Mega CD model1 BIOS menus.
  + PSP: added additional "set to 4:3 scaled" display option for convenience.
  + PSP: Added an option to disable frame limitter (works only with non-auto frameskip).

'''1.35'''
  + PSP port added. Lots of new code for it. Integrated modified FAME/C, CZ80 cores.
  + Some minor generic optimizations.
  * Patched some code which was crashing under PSP, but was working in GP2X/Giz
    (although it should have crashed there too).
  * Readme updated.

'''1.34'''
  + Gizmondo port added.
  + Some new optimizations in memory handlers, and for shadow/hilight mode.
  + Added some hacks to make more games work without enabling "accurate timing".
  * Adjusted timing for "accurate timing" mode and added preliminary VDP FIFO
    emulation. Fixes Double Dragon 2, tearing in Chaos Engine and some other games.
  * Fixed a few games not having sound at startup.
  * Updated serial EEPROM code to support more games. Thanks to EkeEke for
    providing info about additional EEPROM types and game mappers.
  * The above change fixed hang of NBA Jam.
  * Minor adjustments to control configurator.

'''1.33'''
  * Updated Cyclone core to 0.0088.
  + Added A r k's usbjoy fix.
  + Added "perfect vsync" option, which adjusts GP2X LCD refresh rate and syncs
    emulation to it to eliminate tearing and ensure smoothest scrolling possible.
  + Added an option to use A_SN's camma curve for gamma correction (improves dark
    and bright color display for mk2s).
  * Sometimes stray sounds were played after loading a savestate. Fixed.
  * Fixed a problem where >6MB mp3s were corrupted in memory (sound glitches in
    Snatcher).
  * PD no longer overwrites video player code in memory, video player now can be
    used after exiting PicoDrive.
  * Fixed a bug which was causing Sonic 3 code to deadlock in some rare conditions
    if "accurate timing" was not enabled.
  * Fixed support for large hacked ROMs like "Ultimate Mortal Kombat Trilogy".
    Upto 10MB hacked ROMs are supported now.
  + Config profiles added (press left/right when saving config).
  * Changed key configuration behavior to the one from gpfce (should be more
    intuitive).
  + Added some skinning capabilities to the menu system with default skin by
    ketchupgun. Delete skin directory if you want old behaviour.
  * Some other little tweaks I forgot about.

'''1.32'''
  + Added some new scaling options.
  + Added ability to reload CD images while game is running (needed for games
    with multiple CDs, like Night Trap).
  + Added RAM cart emulation.
  * Fixed DMA timing emulation (caused lock-ups for some genesis games).
  * Idle loop detection was picking up wrong code and causing glitches, fixed.
  * The ym2612 code on 940 now can handle multiple updates per frame
    (fixes Thunger Force III "seiren" level drums for example).
  * Memory handlers were ignoring some writes to PSG chip, fixed (missing sounds in
    Popful Mail, Silpheed).
  * Improved z80 timing, should fix some sound problems.
  * Fixed a bug with sram register (fixes Phantasy Star 4).
  * ROM loader was incorrectly identifying some ROMs as invalid. Fixed.
  * Added code for PRG ram write protection register (Dungeon Explorer).
  * The memory mode register change in 1.31 was unsafe and caused some glitches in
    AH-3 Thunderstrike. Fixed.
  * Fixed a file descriptor leak.
  * Updated documentation, added Gmenu2x manual.

'''1.31'''
  * Changed the way memory mode register is read (fixes Lunar 2, broken in 1.30).
  * Fixed TAS opcode on sub-68k side (fixes Batman games).
  * File browser now filters out mp3s, saves and some other files, which are not ROMS.

'''1.30'''
  + ISO files now can be zipped. Note that this causes VERY long loading times.
  + Added data pre-buffering support, this allows to reduce frequency of short pauses
    in FMV games (caused by SD access), but makes those pauses longer.
  * Fixed PCM DMA transfers (intro FMV in Popful Mail).
  + Properly implemented "decode" data transformation (Jaguar XJ220).
  * Integrated "better sync" code into cyclone code, what made this mode much faster.
  * Fixed a bug related to game specific config saving.
  * Frameskipper was skipping sound processing, what caused some audio desyncs. Fixed.
  * Fixed reset not working for some games.
  + New assembly optimized memory handlers for CD (gives at least a few fps).
    Also re-enabled all optimizations from 0.964 release.
  + New idle-loop detection code for sub-68k. Speeds up at least a few games.

'''1.201'''
  + Added basic cheat support (GameGenie and Genecyst patches).

'''1.20'''
  * Fixed a long-standing problem in audio mixing code which caused slight distortions
    at lower sample rates.
  * Changed the way 920 and 940 communicates (again), should be more reliable and give
    slight performance increase.
  * Some optimizations in audio mixing code.
  * Some menu changes (background added, smaller font in ROM browser, savestate loader
    now can select slots).
  + 1M mode DMA transfers implemented (used by FMV games like Night Trap and Sewer Shark).
  + Games now can run code from WORD RAM in 1M mode (fixes Adventures of Willy Beamish).
  + "Cell arrange" address mapping is now emulated (Heart of the alien).
  + "Color numeric operation" is now emulated (text in Lunar 2, Silpheed intro graphics).
  + "Better sync" option added (prevents some games from hanging).

'''1.14'''
  + Region autodetection now can be customized.
  * When CDDA music tracks changed, old buffer contents were incorrectly played. Fixed.
  * BRAM is now automatically formatted (no need to enter BIOS menu and format any more).
  * Games now can be reset, CDDA music no longer breaks after loading another ISO.
  * Fixed a race condition between 920 and 940 which sometimes caused CDDA music not to play.
  + Savestates implemented for Sega/Mega CD.
  + PCM sound added.
  * Some mixer code rewritten in asm. 22kHz and 11kHz sound rates are now supported in
    Mega CD mode (but mp3s must still be 44kHz stereo).
  + Timer emulation added.
  * CDC DMA tansfers fixed. Snatcher and probably some more games now boot.
  * 2M word RAM -> VDP transfers fixed, no more corruption in Ecco and some other games.

'''1.10'''
  + GP2X: Added experimental Sega CD support.
  + GP2X: Added partial gmv movie playback support.

'''0.964'''
  * GP2X: Fixed a sound buffer underflow issue on lower sample rate modes, which was
          happening for NTSC games and causing sound clicks.
  * GP2X: Redone key config to better support USB joysticks (now multiple joysticks
          should be useable and configurable).
  + GP2X: Added save confirmation option.
  + GP2X: Added 940 CPU crash detection.
  + ALL:  UIQ3 port added.

'''0.963'''
  * GP2X: Gamma-reset-on-entering-menu bug fixed.
  * GP2X: Recompiled PicoDrive with gcc profiling option set as described here:
          http://www.gp32x.com/board/index.php?showtopic=28490

'''0.962'''
  * GP2X: Fixed an issue with incorrect sounds in some games when dualcore operation
          was enabled (for example punch sound in SOR).
  * GP2X: Limited max volume to 90, because higher values often cause distortions.
  * GP2X: Fixed a bug with lower res scaling.
  * GP2X: Gamma is now reset on exit.

'''0.96'''
  * ALL:  Severely optimized MAME's YM2612 core, part of it is now rewritten in asm.
  + GP2X: The YM2612's code now can be run in GP2X's ARM940T CPU, what causes large
          performance increase.
  * ALL:  Accurate renderers are slightly faster now.
  + GP2X: Using quadruple buffering instead of doublebuffer now, also updated
          framelimitter, this should eliminate some scrolling and tearing problems.
  * GP2X: Fixed some flickering issues of 8bit accurate renderer.
  + GP2X: craigix's RAM timings now can be enabled in the menu (see advanced options).
  + GP2X: Added ability to save config for specific games only.
  + GP2X: Gamma control added (using GP2X's hardware capabilities for this).
  * GP2X: Volume keys are now configurable.
  + GP2X: GnoStiC added USB joystick support, I made it possible to use it for
          player 2 control (currently untested).
  * GP2X: squidgehack is now applied through kernel module (cleaner way).

'''0.95'''
  * ALL:  Fixed a bug in sprite renderer which was causing slowdowns for some games.
  + GP2X: Added command line support
  + GP2X: Added optional hardware scaling for lower-res games like Shining Force.
  * ALL:  Sound chips are now sampled 2 times per frame. This fixed some games which
          had missing sounds (Vectorman 2 1st level, Thunder Force 3 water level,
	      etc.).
  + ALL:  Added another accurate 8-bit renderer which is slightly faster and made it
          default.

'''0.945'''
  + GP2X: Added frame limiter for frameskipped modes.
  * GP2X: Increased brightness a bit (unused pixel bits now also contain data).
  * GP2X: Suidgehack was not applied correctly (was applied before allocating some
          high memory and had no effect).

'''0.94'''
  + Added GP2X port.
  * Improved interrupt timing, Mazin Saga and Burning Force now works.
  * Rewritten renderer code to better suit GP2X, should be faster on other
    ports too.
  + Added support for banking used by 12-in-1 and 4-in-1 ROMs (thanks Haze).
  + Added some protection device faking, used by some unlicensed games like
    Super Bubble Bobble, King of Fighters, Elf Wor, ... (thanks to Haze again)
  + Added primitive Virtua Racing SVP faking, so menus can be seen now.

'''0.93'''
  * Fixed a problem with P900/P910 key configuration in FC mode.
  * Improved shadow/hilight mode emulation. Still not perfect, but should be
    enough for most games.
  + Save state slots added.
  + Region selector added.

'''0.92'''
  VDP changes:
  * VDP emulation is now more accurate (fixes flickering in Chase HQ II,
    Super Hang-On and some other problems in other games).
  * HV counter emulation is now much more accurate. Fixes the Asterix games,
    line in Road Rash 3, etc.
  * Minor sprite and layer scroll masking bugs fixed.
  + Added partial interlace mode renderer (Sonic 2 vs mode)
  * Fixed a crash in both renderers when certain size window layers were used.
  + Added emulation of shadow/hilight operator sprites. Other shadow/hilight
    effects are still unemulated.
  + Sprite emulation is more accurate, sprite limit is emulated.
  + Added "accurate sprites" option, which always draws sprites in correct
    order and emulates sprite collision bit, but is significantly slower.

  Emulation changes:
  * Improved interrupt handling, added deferred interrupt emulation
    (Lemmings, etc).
  + Added serial EEPROM SRAM support (Wonder Boy in Monster World,
    Megaman - The Wily Wars and many EA sports games like NBA Jam).
  + Implemented ROM banking for Super Street Fighter II - The New Challengers
  * Updated to the latest version of DrZ80 core, integrated memory handlers
    in it for better performance. A noticeable performance increase, but save
	states may not work from the previous version (you can only use them with
	sound disabled in that case).
  + SRAM word read handler was using incorrect byte order, fixed.

  Changes in Cyclone 0.0086:
  + Added missing CHK opcode handler (used by SeaQuest DSV).
  + Added missing TAS opcode handler (Gargoyles,Bubba N Stix,...). As in real genesis,
    memory write-back phase is ignored (but can be enabled in config.h if needed).
  + Added missing NBCD and TRAPV opcode handlers.
  + Added missing addressing mode for CMP/EOR.
  + Added some minor optimizations.
  - Removed 216 handlers for 2927 opcodes which were generated for invalid addressing modes.
  + Fixed flags for ASL, NEG, NEGX, DIVU, ADDX, SUBX, ROXR.
  + Bugs fixed in MOVEP, LINK, ADDQ, DIVS handlers.
  * Undocumented flags for CHK, ABCD, SBCD and NBCD are now emulated the same way as in Musashi.
  + Added Uninitialized Interrupt emulation.
  + Altered timing for about half of opcodes to match Musashi's.

'''0.80'''
  * Nearly all VDP code was rewritten in ARM asm. Gives ~10-25% performance
    increase (depends on game).
  * Optimized 32-column renderer not to render tiles offscreen, games which
    use 32-column display (like Shining Force) run ~50% faster.
  + Added new "Alternative renderer", which gives another ~30-45% performance
    increase (in addition to mentioned above), but works only with some games,
    because it is missing some features (it uses tile-based renderering
    instead of default line-based and disables H-ints).
  + Added "fit2" display mode for all FC gamers. It always uses 208x146 for
    P800 and 208x208 for all other phones.
  + Added volume control for Motorolas (experimental).

  VDP changes:
  + Added support for vertical window (used by Vapor Trail, Mercs, GRIND
    Stormer and others).
  + Added sprite masking (hiding), adds some speed.
  + Added preliminary H counter emulation. Comix Zone and Sonic 3D Blast
    special stage are now playable.
  + Added column based vertical scrolling (Gunstar Heroes battleship level,
    Sonic and Knuckles lava boss, etc).

  Emulation changes:
  + Re-added and improved Z80 faking when Z80 is disabled. Many games now can
    be played without enabling Z80 (Lost Vikings, Syndicate, etc), but some
    still need it (International Superstar Soccer Deluxe).
  * Improved ym2612 timers, Outrun music plays at correct speed, voices in
    Earthworm Jim play better, more games play sound.
  * I/O registers now remember their values (needed for Pirates! Gold)
  + Added support for 6 button pad.

  Changes in Cyclone 0.0083wip:
  + Added missing CHK opcode (used by SeaQuest DSV).
  + Added missing TAS opcode (Gargoyles). As in real genesis, write-back phase
    is ignored (but is enabled for other systems).

  Backported stuff from Snes9x:
  * Fixed Pxxx jog up/down which were not working in game.
  + Added an option to gzip save states to save space.
  + The emulator now pauses whenever it is loosing focus, so it will now pause
    when alarm/ponecall/battery low/... windows come up.
  - Removed 'pause on phonecall' feature, as it is no longer needed.
  + Video fix for asian A1000s.

'''0.70'''
  * Started using tools from "Symbian GCC Improvement Project", which give
    considerable speed increase (~4fps in "center 90" mode).
  * Rewrote some drawing routines in ARM assembly (gives ~6 more fps in
    "center 90" mode).
  * Minor improvement to 0 and 180 "fit" modes. Now they look slightly better
    and are faster.
  * Minor stability improvements (emulator is less likely to crash).
  + Added some background for OSD text for better readability.
  + Added Pal/NTSC detection. This is needed for proper sound speed.
  + Implemented Reesy's DrZ80 Z80 emu. Made some changes to it with hope to make
    it faster.
  + Implemented ym2612 emu from the MAME project. Runs well but sometimes sounds
    a bit weird. Could be a little faster, so made some changes too.
  + Implemented SN76489 emu from the MAME project.
  + Added two separate sound output methods (mediaserver and cmaudiofb) with
    autodetection (needs testing).
  * Fixed VDP DMA fill emulation (as described in Charles MacDonald's docs),
    fixes Contra and some other games.

'''0.301'''
  Launcher:
  * Launcher now starts emulation process from current directory,
    not from hardcoded paths.
  * Improved 'pause on call' feature, should hopefully work with Motorola phones.

'''0.30'''
  Initial release.