• Disclaimers
• New in This Version
• History
• Introduction
• VGBA Ports
• Registered Users
• What is Included
• What is not Included
• Buttons
• Command Line Options
• Frequently Asked Questions
• Notes to Demo Authors
• Thanks

• GameBoy and GameBoy Advance are registered trademarks of Nintendo.
• The author is in no way affiliated with Nintendo.
• The author is in no way affiliated with any pirate group out there.
• The author cannot and will not provide you with any GameBoy or GameBoy Advance games.
• The author cannot be held responsible for anything this program will do to your computer, brains, free time, housemates, pets, or family members.

• Added a routine that guesses correct FlashROM ID and the FlashROM or EEPROM size from the cartridge ID. Super Mario Brothers 3 and Pokemon Sapphire work now. Use -guesshw and -defaulthw options to switch guessing on and off.
• Added DirectDraw-based full screen mode to VGBA-Windows. Press [ALT]+[ENTER] to switch in and out of the full screen mode. Use it with caution, as DirectDraw is notoriously unstable.
• Fixed ARM LDM/STM opcodes to ignore lower two bits of address.
• Fixed ARM MSR opcode to allow setting any of the four areas in the CPSR and SPSR registers.
• Fixed a bug in the character screen drawing code that could crash the program.
• Finally fixed the time counting bug that caused bad sound distortions in many games, especially when using the -ds 1 sound rendering option.
• Now resetting the line coincidence flag on writes to DISPSTAT to enable line coincidence interrupts at each scanline (F-Zero 2).
• Changed FastSet() BIOS call to round transfer size to the nearest multiple of 8 quads (32 bytes) and check source address for bounds.
• Fixed several bugs in the MIDI logging code and the MIDI sound driver in VGBA-Windows.
• Added fast-forwarding option ([PAGEUP]).
• Added TV raster simulation to VGBA-Windows and VGBA-MSDOS.
• Added VGBA-Windows options to set FlashROM ID and hardware guessing mode.
• Raised the maximal "Sync to..." frequency to 200Hz.
• Window size and position are now saved on exit in VGBA-Windows.

New in Version 2.1

• Save (.SAV) file format has changed due to addition of >64kB FlashROMs.
• State (.STA) file format has changed due to addition of RTC and >64kB FlashROMs.
• The old -flash has been changed to -flashid.
• The new -flash sets the number of FlashROM address bits (≥16).
• Added RTC support (clock in Pokemon series).
• Added support for >64kB FlashROMs (Pokemon series, etc.).
• Added MIDIKey2Freq() to the BIOS emulation (thanks to Aaron Oneal).
• Fixed a bug in the ArcTan2() emulation (Castlevania: Aria Of Sorrow).
• Fixed possible memory corruption in EEPROM emulation (Lord Of The Rings).
• Fixed SMULL/SMLAL opcodes.
• VBlank interrupt now occurs with HBlank in line 160 (Robot Wars).
• Now recomputing sprites every time screen mode changes (Ice Age).
• Now setting unused KEYSTAT bits to zeroes (Defender Of The Crown).
• Now updating C flag when immediate value is rotated in an ALU operation (Desert Strike).

New in Version 2.0

• Majorly redesigned screen rendering routines, making them faster.
• Added sprite sorting and precomputation to speed things up.
• Fixed window rendering.
• Fixed multiple screen rendering bugs.
• Color effects can now be disabled in WININ/WINOUT registers.
• Alpha blending can now be applied multiple times (Lord Of The Rings).
• Disabled alpha blending for pixels with no second argument (Lord Of The Rings).
• Added window support to bitmapped screen modes.
• Disabled display of the first 512 sprite patterns in bitmapped screen modes.
• Changed LDM instructions not to write back base register if it has just been loaded from memory (Golden Sun 2, Kong, VRally 3, etc.).
• Now setting R12=0x04000000 in VBlankIntrWait() and IntrWait() (Bubble Bobble Old And New).
• Added QOpARM() and WOpARM() functions for fast opcode fetching.
• Removed data rotation in unaligned 32bit writes (Downforce).
• Modified BIOS decoders that write to VRAM to use words, not bytes.
• Now returning correct "broken" values when program tries to read BIOS area by bytes and 16bit words.
• Now doubling byte writes to VRAM and palette.
• Now mirroring VRAM as 64kB+2*32kB.
• Now mirroring SRAM, OAM, and palette.
• Removed mirroring of I/O addresses.
• Now waiting for sound thread to die in VGBA-Unix.

New in Version 1.7

• Switched to the latest version of the OpenWatcom C/C++ compiler.
• The infamous Windows problem with spaces in directory names seems to be fixed by using a newer compiler.
• Joystick problems in VGBA-Windows are fixed.
• Added joystick configuration to VGBA-Windows setup panel.
• Fixed sound in VGBA-Windows on Windows 2000.

New in Version 1.6

• VGBA-MSDOS now comes with the VGBA-Windows!
• Implemented BIOSChecksum() BIOS call (SWI#0D).
• Implemented BitUnpack() BIOS call (SWI#10).
• Implemented GetJumpList() BIOS call (SWI#2A).
• Added a -verbose bit to print sound-related messages.

New in Version 1.5

• Added strict type/source checking to BIOS uncompression routines.
• Fixed direct sound to melodic sound volume ratio.
• Added optional waveforms to melodic (non-PCM) channels.
• Fixed updates to the melodic PCM channel.
• Fixed melodic volume sweep.
• Fixed a bug that broke timers when restoring saved state.
• Fixed a problem with prematurely closed stdin in VGBA-Unix.

New in Version 1.4

• State save (.STA) file format has changed!
• Improved direct sound emulation by tinkering with sound driver API.
• Added BIOS read-protection.
• Added support for different EEPROM sizes (-eeprom). Some new GBA games use 16384x64 EEPROMs (use -eeprom 14 option with these games).
• Fixed disassembler to show LDRH/STRH operations with immediate offset.
• Added support for LDRH/STRH operations with post-indexing and write-back modes both "on". This is still wrong, folks. Please, read the ARM7TDMI documentation and modify your assemblers to generate correct opcodes.
• Now updating timer data registers with current counter values.
• Now clearing OAM and some other registers on reset.
• Now enabling interrupts in VBlankIntrWait() and IntrWait().
• Now ignoring compression type tags in RLUncompress() (Lego Racers 2).
• Fixed LDM/STM opcodes to handle USER mode R13/R14 load/save.
• Fixed mode changes in LDM opcode.
• Fixed DMA debugging message.
• Added more manufacturer IDs to the database.

New in Version 1.3

• Added console-based debugger to the VGBA-Windows, by public demand.
• Fixed MULL/SMULL opcode (thanks go to Santeri Paavolainen).
• Added forced VBlank emulation.
• Filled simulated BIOS area with the value that real copy-protected BIOS returns on reads.
• Fixed EEPROM emulation a little bit.
• Made "channels active" sound register visible to the GBA.
• Added more manufacturer IDs to the database.
• Fixed rollover on the volume control button in VGBA-Windows.
• Fixed command line parsing in VGBA-Windows.
• Now turning off sound when VGBA-Windows dialog boxes get shown.
• VGBA-Windows now always uses .INI file in the same directory as the .EXE file.

New in Version 1.2

• Implemented direct sound channels.
• Added dual banks for the melodic sound channel #3.
• Added master volume for direct and melodic sound (SOUNDCNT_H).
• Added direct sound DMA interrupts (Pac-Man Collection).
• Added serial I/O interrupts (Golf Master).
• Added Diff8bitUnFilterWRAM(), Diff8bitUnFilterVRAM(), and Diff16bitUnFilter() BIOS calls.
• Added more manufacturer IDs to the database.
• Disabled DMA restart (sound in Wario World 4, etc.).
• Fixed a bug that screwed up timers after DMA transfers.
• Fixed WRdARM() function and macro handling of unaligned reads.
• Fixed IntrWait() and VBlankIntrWait() BIOS calls (SWI #4,5).
• Fixed long-multiply instructions (Tony Hawk Pro Skater 2).
• Fixed ARM-mode SWIs (Super Black Bass Advance).
• Somewhat changed timings during uncompression BIOS calls.
• Changed simulated BIOS contents a little (Tactics Ogre).
• Set USER mode stack to correct value.
• Now initializing CPU into SYSTEM mode, no other flags.
• Changed default FlashID to a real one (was 0x0000).
• Fixed LDSH/LDSB THUMB mnemonics in the disassembler.
• Added ability to supply FlashID from command line in VGBA-Unix and VGBA-MSDOS.
• Added GBA-specific calls to the GameBoy sound chip API.
• Changed SetWave() sound API call to use shared buffers, as needed for direct sound.
• Implemented threaded Unix sound driver.
• Shrunk sound buffer size in the Windows sound driver to 256 bytes for clearer sound.
• Changed master volume control usage in all sound drivers for more efficient and correct mixing.
• Updated documentation, fixing some HTML errors.

New in Version 1.1

• Added support for rectangular and sprite windows.
• Added BgAffineSet() BIOS call.
• Added more manufacturer IDs to the database.
• Added support for GZIPped ROM images and state file.
• Improved fast QRdARM() macro to handle unaligned addresses (albeit not ideally).
• Fixed alpha-blending operation a bit.
• Now saving serial EEPROM contents in the .SAV file, after the FlashROM contents.
• Removed CRC check as it was wrong and did not make any sense. Only CMP is checked now.
• Fixed sprite priorities relative to background priorities in screen modes 0..2.
• Optimized drawing routines for rotated/scaled backgrounds and sprites.
• Now saving EEPROM state in state files (.STA format has changed).
• Fixed joystick support in VGBA-Windows (somewhat).
• Fixed VGBA-Unix to allow window managers (like WindowMaker) create an application icon for it.

New in Version 1.0

• VGBA-Windows is now available. Register it NOW!
• VGBA-Unix is now available.
• Added facility to save and load emulation state.
• Added serial EEPROM emulation.
• Implemented more or less accurate CPU cycle counting (still not accurate enough though).
• Implemented HuffUncomp() call.
• Fixed ObjAffineSet(), CpuSet(), CpuFastSet(), and SoftReset() calls.
• Fixed timers to reload values correctly.
• Majorly updated documentation.
• Fixed background color problem in the non-VESA (256 color) version of VGBA-MSDOS.

New in Version 0.6

• Added JEDEC FlashROM support.
• Added CRC/CMP check. All failing cartridges will now be rejected unless you use the -nocrc option.
• Implemented pending IRQ handling after IRQs were switched on.
• Disabled IRQs in the SVC mode.
• Added ObjAffineSet() BIOS call.
• Added Halt() and Stop() BIOS calls.
• Fixed several BIOS calls.
• Fixed a special case of DMA with the length of 0 items.
• Fixed LDR/STR/LDRB/STRB instruction display in the debugger.
• Improved cartridge information reporting.
• Added a lot of command line options.
• Added a lot of control keys.

New in Version 0.5

• Moved dummy GBA.ROM contents inside the VGBA code.
• Added DMA3 start at the beginning of HRefresh.
• Added 'v' command to the debugger to show GBA status.
• Fixed transparency effects in bitmap modes.
• Fixed transparency with multiple backgrounds.
• Now initializing rotation/scaling properly.
• No longer supporting 128kB flash ROM above the cartridge ROM.

New in Version 0.4

• Added MULL/MLAL ARM opcodes.
• Added color effects to all screen modes.
• Added rotation to all appropriate screen modes.
• Added rotation to sprites.
• Fixed DMA transfers to start correctly.
• Fixed DMA transfers to leave correct values in DMACONT registers.
• Added IRQ at the end of DMA transfer, if required.
• Fixed GB sound chip emulation.
• Added CPUSet() and CPUFastSet() BIOS calls.
• Added RLUnCompWRAM() and RLUnCompVRAM() BIOS calls.
• Now saving cartridge SRAM and flash ROM into a .SAV file.
• Both 16bit color and 8bit color versions are included. 16bit version requires VESA-compatible video card. I still recommend it over the 8bit version as GBA programs are extremely ugly in 256 colors :)

VGBA is a logical continuation of my previous work in videogame emulation, namely, the Virtual GameBoy that emulates GameBoy Classic, GameBoy Pocket, Super GameBoy, and GameBoy Color. VGBA is a completely different program though. It will not run the original GameBoy software, so you will have to use VGB for that.

I am mainly releasing VGBA for game developers and hobbyists who would like to code for GBA but cannot afford to buy an official development kit from Nintendo. VGBA is not a replacement for the real development kit, as it does not contain any real GBA hardware, but it is a cheap and reliable way to test your code and show your work to the publisher.

Windows 95/98/ME/NT/2000/XP

The Windows and MSDOS versions of VGBA are available from me, Marat Fayzullin, for $35US. This fee ensures that you will get you the latest full versions of both VGBA-Windows and VGBA-MSDOS with support and free updates via email as long as I update these programs. For more information, take a look at

http://www.komkon.org/fms/VGBA/VGBAWindows.html

You can register VGBA-Windows and VGBA-MSDOS by one of the following methods:

ORDER BY MAIL

Send $35US in cash, money order, or a US bank check to:

     Marat Fayzullin
     3030 Southview Road
     Ellicott City, MD 21042
     USA

Don't forget to include your email address and mention that you want VGBA-Windows, as I'm selling several other products as well. The software will be emailed to you as soon as I receive the money.

ORDER ON THE WEB

Tell your WWW browser to go to

http://www.digibuy.com/cgi-bin/order.html?296825+99046733021

and use the online form to register VGBA-Windows. You can pay with a credit card. They take MasterCard, Visa, Amex, or Discover and also allow to register over the phone. The software will be emailed to you as soon as I receive the notification from DigiBuy.

MSDOS

The first (<1.0) versions of VGBA were released for MSDOS. You may find them on the Net for free, but they lack the compatibility and features of the later versions. The newer (>1.5) versions of VGBA-MSDOS are sold as part of the VGBA-Windows package. VGBA-MSDOS has been compiled to run with the DOS4GW extender on MSDOS and Windows platforms. It uses a 320x200x16bit VESA screen and therefore requires VESA support. It will fail on your computer if you do not have VESA support for the 320x200x16bit screen mode.

Unix

I have compiled VGBA for several different flavors of Unix and made the binaries available for free at the VGBA homepage. The current VGBA-Unix has several important requirements though:

• Current VGBA core code will only run on low-endian systems. This excludes SPARC, 680x0, PowerPC, and some other architectures from the list of possible ports. I'm hoping to add high-endian support in the future.
• As GBA video hardware is capable of displaying 32768 colors, and GBA programs use this capability extensively, I am only providing VGBA-Unix binary compiled for the 16bit color. If your Xserver is unable to support this resolution, VGBA-Unix will not run on it.
• Since version 1.2, VGBA-Unix uses threaded sound driver. This means that your Unix must support POSIX ¥hreads, or VGBA-Unix will not run. On the systems with optional threads support, please, add this support prior to running VGBA-Unix.

I understand that the previous paragraph may sound threatening to some people, but this kind of piracy really hurts my profits and feelings. I've put a lot of effort into VGBA, and can only continue working on it if people do not try to cheat on me.

It may also be a good idea to buy a real cartridge for each GameBoy Advance ROM image you use with the emulator. GameBoy Advance software is copyrighted, but as long as you own the real cartridge, you are protected by the law allowing customers to backup bought software.

• ARM7TDMI CPU with ARM and THUMB opcode sets.
• Internal RAM at addresses 0x03000000 (32kB) and 0x02000000 (256kB).
• Cartridge ROM at address 0x08000000, mirrored at 0x0A000000 and 0x0C000000.
• Cartridge RAM at address 0x0E000000 (64kB).
• Cartridge FlashROM (JEDEC) at address 0x0E000000 (64kB).
• Cartridge serial EEPROM at address 0x09000000 (64x64bits), mirrored at 0x0B000000 and 0x0D000000.
• Interrupts: VBlank, HBlank, line coincidence, timers, DMA, joypad.
• Timers: TIMER0, TIMER1, TIMER2, TIMER3.
• DMA channels: DMA0, DMA1, DMA2, DMA3.
• DMA modes (instantaneous, HBlank, VBlank, HRefresh) and repeat feature.
• Joypad buttons and interrupts.
• GameBoy-compatible melodic sound chip with GBA extensions.
• Two channels of GBA-specific "direct" sound.

• DMA happens "instantly".
• CPU timings are close but not entirely correct. VGBA considers all memory accesses as "sequential". There are some other discrepancies as well, but overally, it should be pretty close.

Including the real Nintendo BIOS with the emulator would be a copyright violation. Therefore, I have tried to simulate GBA BIOS routines by trapping and handling ARM SWI opcodes. GBA BIOS is now fully emulated except for the built-in music player and some networking routines. Here is the list of supported BIOS calls:

The VGBA WWW page contains some links to GameBoy Advance cartridge copier info. Cartridge copiers can be used to dump GameBoy Advance cartridges into files. I cannot provide you with any additional information about these copiers, so do not send me email asking for this information. Use the copier-related links at the VGBA WWW page.

GameBoy Advance has a BIOS ROM inside with some useful subroutines. Including the real Nintendo BIOS with the emulator would be clearly illegal. Instead, VGBA tries to simulate GBA BIOS routines. It still has an option to use the real BIOS supplied from the GBA.ROM file in the current directory. I cannot tell you where to find the real BIOS, so do not ask me about it. The BIOS simulation is quite functional and becomes better over time. It also runs faster than the real BIOS would on the emulator.

  [SPACE]    - A button (also: [LALT],A,S,D,F,G,H,J,K,L)
  [LCONTROL] - B button (also: Z,X,C,V,B,N,M)
  [Q]        - LEFT button (also: E,T,U,O)
  [W]        - RIGHT button (also: R,Y,I,P)
  [TAB]      - SELECT button
  [ENTER]    - START button
  [ESC]      - Quit emulation (also: [F12])
  [F2]       - Turn soundtrack logging on/off
  [F3]       - Turn A button autofire on/off
  [F4]       - Turn B button autofire on/off
  [F5]       - Turn LEFT button autofire on/off
  [F6]       - Turn RIGHT button autofire on/off
  [F7]       - Save emulation state to .STA file
  [F8]       - Load emulation state from .STA file
  [F9]       - Fast-forward emulation (also: [PAGEUP])
  [F11]      - Reset GBA hardware
  [F12]      - Quit emulation (also: [ESC])
  [PAGEUP]   - Fast-forward emulation (also: [F9])
  [5]-[8]    - Turn backgrounds display on/off
  [9]        - Turn sprites display on/off

With #define DEBUG:
  [F1]       - Go into the built-in debugger

With #define SOUND:
  [-]        - Decrease sound volume
  [=]        - Increase sound volume
  [0]        - Turn all sound on/off
  [1]-[4]    - Turn melodic sound channels on/off
  [[],[]]    - Turn direct sound channels on/off

vgba [-option1 [-option2...]] [FILENAME.GBA]

  -uperiod <period>   - Number of interrupts per screen update [1]
  -verbose <level>    - Select debugging messages [1]
                          0 - Silent          1 - Startup messages
                          2 - I/O accesses    4 - Illegal memory accesses
                          8 - DMA transfers  16 - Illegal CPU ops
                         32 - SWI calls      64 - FlashROM/EEEPROM/RTC
                        128 - Sound messages
  -crc/-nocrc         - Check cartridge CRC/CMP [-crc]
  -guesshw/-defaulthw - Guess FlashROM/EEPROM ID and size [-guesshw]
  -flashid <id>       - Set FlashROM maker/device ID [D4BFh]
  -flash <bits>       - Set FlashROM size, ≥16 bits [17]
  -eeprom <bits>      - Set EEPROM size, 6..16 bits [6]
  -logsnd <filename>  - Write soundtrack to a MIDI file [LOG.MID]
  -ds <method>        - Sound rendering method [0]
                        0 - Automatic          1 - Accurate
                        2 - Fast
  -sync <frequency>   - Sync screen updates to <frequency> [-nosync]
                        (<frequency> must be in 20Hz..100Hz range)
  -nosync             - Do not sync screen updates

With #define SOUND:
  -sound [<quality>]  - Sound emulation quality [44100]
                        0 - Off                1 - Adlib (MSDOS)
                        Values >8191 are treated as wave synthesis
                        frequencies.
  -nosound            - Same as '-sound 0'

With #define DEBUG:
  -trap <address>     - Trap execution when PC reaches address [FFFFh]
                        When a keyword 'now' is used in place of the
                        <address>, execution will trap immediately.

With #define MSDOS:
  -vsync              - Sync screen updates to VBlank [-nosync]
  -tv/-notv           - Simulate TV raster lines [-notv]

With #define UNIX:
  -saver/-nosaver     - Save CPU when inactive [-saver]
  -scale <factor>     - Scale window by <factor> [1]

With #define MITSHM:
  -shm/-noshm         - Use MIT SHM extensions for X [-shm]

1. I WANNA PLAY GAMES!!!! WHERE DO I GET GAMES???????
   I do not know. I can't give you any due to both legal and moral reasons. Please, do not mail me asking for games. I will delete your mail right away, and you won't get an answer.

2. Can I play GameBoy Classic and GameBoy Color games on VGBA?
   No, you can't. GameBoy Advance hardware is completely different from the older GameBoy and GameBoy Color models. To play older games, you may want to consider my other emulator, Virtual GameBoy (VGB) .

3. How do I copy games from cartridges to a computer?
   You can use a special device called cartridge copier, such as Flash Advance Linker from Lik-Sang. Don't forget to get a rewritable flash card too.

4. What is GameBoy Advance? How its hardware works?
   GameBoy Advance (GBA) is a handheld videogame machine made by Nintendo. Its hardware has nothing to do with GameBoy and GameBoy Color handhelds previously produced by Nintendo. GBA is built around an ARM7TDMI 32bit CPU running at 16MHz. GBA video subsystem is very similar to that of SNES, but more advanced. The sound subsystem uses direct sample output. GBA also includes the four-channel melodic sound chip from the original GameBoy.

   In order to be compatible with the original GB/GBC, GBA includes the complete set of GBC hardware. This hardware (aside from the sound chip) is not accessible from the GBA side and only used when somebody inserts a GB/GBC cartridge into GBA.

5. There is no version of VGBA for my Unix!
   I am trying to compile Unix binaries for as many flavors of Unix as possible, but as I do not have access to many machines, do not expect immediate support for every Unix flavor out there. Don't mail me asking for the source either: VGBA source code is not publicly distrbutable, as much as I regret to say this :(.

6. My favorite game doesn't work on VGBA. What do I do?
   There may be several reasons why a game has problems running on VGBA or does not run at all.
   • If emulator does not even recognize the ROM image, its CRC or CMP may be wrong. Try turning CRC checking off by using the -nocrc option or clearing "Check Cartridge CMP" checkbox in VGBA-Windows Setup Panel. You really ought to find an uncorrupted ROM image though.

   • The game may be using a different EEPROM type. EEPROM is a little chip that sits on a cartridge and stores save-games. Some GBA games use 64x64 EEPROMs (-eeprom 6) while others use 16384x64 EEPROMs (-eeprom 14). In VGBA-Windows, you can simply select the EEPROM type from the Setup Panel.

   • If some sprites blink or do not appear at all, try changing -uperiod value (1 will give you the best picture, but the slowest emulation), or moving an "Update Period" knob in the VGBA-Windows Setup Panel.

   • VGBA may not currently run this game. Not all games are supported at this moment. Don't expect 100% compatibility with the real hardware. At least, not yet :).

7. There is no sound!
   Since version 1.2, VGBA emulates both "melodic" (GameBoy-compatible) and "direct" (GBA-specific) sound hardware. When using VGBA-Windows, you will have to turn "Use MIDI for sound" option off to hear the direct sound channels, as MIDI cannot be used to play direct sound. Also make sure that direct sound channels are turned on in the Setup Panel.

8. Direct sound sounds really bad!
   Use -ds command line option (or corresponding options in the VGBA-Windows Setup Panel) to choose the way VGBA renders direct sound. In Windows, you should also try changing volume, sound rate, and the number of sound buffers. If this doesn't help, you may be out of luck. Hopefully, sound emulation becomes better in the upcoming versions.

9. Why is VGBA so slow on my machine?
   Because your machine is too slow to run VGBA. My experience shows that you need at least a PentiumII/400 machine with fast video to run VGBA at a reasonable speed. Following are the ways to speed things up:
   • Increase Update Period. The picture will get more jerky, but VGBA will become faster.

   • On Unix, always use MIT Shared Memory Extension for X (MITSHM). This, of course, means that you have to run VGB locally.

   • On Windows and Unix, use 1:1 window to achieve the highest speed.

   • On Windows, use MIDI sound, as wave synthesis takes quite a lot of CPU time.

10. VGBA is too fast on my machine! How do I slow it down?
    Frankly, when I started writing VGBA, I never expected that it will be too fast on any machine :). But times change...
    • On Unix, use -sync option to tie screen updates to the certain frequency (usually, 60Hz/UPeriod).

    • On Windows, use "Sync To..." option in the Setup Panel to tie screen updates to a certain frequency (usually, 60Hz divided by UPeriod).

    • Decrease Update Period to 2 or even to 1. The emulation will become much slower, but smoother.

    • On Windows and Unix, double or triple the window size.

11. When starting VGBA-Unix, ld says that some library isn't found.
    This may happen if the versions of your shared libraries are older than the ones for which VGBA has been compiled. A decent way to deal with this is to upgrade your Unix. A quick and dirty way is to make a symbolic link from the existing library to a name required by VGBA.

12. When starting VGBA-Unix, I get X_ShmAttach error.
    You are probably trying to run VGBA-Unix on a remote Xterminal while it attempts to use shared memory for interfacing with X. Use -noshm option to tell it not to use shared memory.

13. When starting VGBA-Unix, I get X_PutImage error.
    VGBA-Unix version currently needs 16bit X. Xterminals that do not support 16bit image format will not work.

14. The sound is distorted in the VGBA-Windows. How do I fix it?
    The wave-synthetized sound in VGBA may become distorted on slow or highly loaded machines (no graphics acceleration, for example). There are several ways you can improve sound:
    • Use MIDI sound instead. It has both advantages and disadvantages though.

    • Make VGBA window smaller to decrease the load on the CPU. 1:1 is the optimal size.

    • Decrease the sound rate (in Setup Panel). The sound may become tinkier, but less distorted.

    • Increase the number of wave buffers (in Setup Panel). This may cause sound to fall a second or two behind the screen action, but the sound quality will become better.

15. Does VGBA-Windows support joystick? My joystick doesn't work!
    VGBA-Windows supports joystick. If your joystick does not work, go into Windows Control Panel to see if it is configured and calibrated properly. Also, some new joysticks working in esoteric standards (like GRiP) are known to have problems.

16. VGBA-Windows starts, but then quits immediately!
    Check the pathname to wherever your VGBA is located. It should not contain spaces. For example, "C:\Program Files\VGBA" is a bad place for VGBA, while "C:\VGBA" will work. This bug is caused by an old version of C compiler I am using. I hope to get rid of it when I switch to a new compiler.
    UPDATE: I have finally switched to a newer compiler in VGBA-Windows 1.7. If you are still encountering this problem, please, let me know.

17. Colors are all screwed up in VGBA-Windows!
    VGBA-Windows requires Windows to be in 65536-color or better color mode. When running Windows in 256-color mode, it will try to approximate colors to existing ones, but expect results to be dismal.

18. Black window in VGBA-Windows!
    If you are running Windows in 256-color mode, then this is most likely the cause of a problem. Try switching Windows into 65536-color or better screen mode.

19. Command line options don't work in VGBA-Windows!
    They shouldn't. The demo version of VGBA-Windows supports no command line interface at all. The full version will only accept the .GBA file name at the command line, but no options. All configuration is done via Setup Panel and VGBA.INI file.

20. Volume control works strangely in VGBA-Windows!
    It is a result of the volume control being shared between VGBA and other Windows applications. You can usually restore normal volume by leaving VGBA window and then activating it again.

21. How do I save and load the GBA state during the game?
    The GBA state can be saved by pressing [F7] button. The resulting data file will have the same name as your .GBA file, but its extension is going to be .STA. You can load state from this file by pressing [F8] at any point in the game. This state file will also be loaded automatically next time you start VGBA. The same state file is not guaranteed to work for versions of VGBA running on a different hardware. State saving is not perfect yet, so for some games state may not be correctly saved.

• Prior to running the program, VGBA will check CMP and CRC of the ROM image. If they do not match CMP/CRC given in the cartridge header, VGBA will refuse to run the program. To make your program run, either fix CMP/CRC (preferable) or use the -nocrc option. Also, be aware that Nintendo requires CRC of a cartridge to be 0 i.e. your ROM image must have padding bytes somewhere that compensate CRC to be zero.
• Many demos use random areas of address space for RAM. Apparently, GBAEmu will create RAM at any address accessed by the program. The real GBA (according to the latest specification) is only going to have RAM at addresses 0x03000000 (32kB) and 0x02000000 (256kB). Use only this memory.
• Many demos use cartridge address space (0x08000000 and up) as RAM. This is not correct as cartridge ROM is not writable. Please, use RAM areas described above.
• In graphical screen modes (MODEs 3,4,5) the entire screen is treated as background #2. This means that to actually show the screen you have to enable background #2 in DISPCONT and set appropriate bits in BG2CONT.
• The backgrounds are shown in the order 0,1,2,3, with background #0 being on top and background #3 on the bottom. When you set different background priorities, the backgrounds with lower priorities will be on top.
• When using ARM data comparison opcodes, you should always set the S flag in the opcode. In fact, ARM7TDMI programming manual explicitely requires this.
• At least two demos (FireDemo and ConsoleDev Demo) are using reads from non-aligned addresses. While non-aligned reads are a documented feature of ARM7TDMI CPU, they are rarely used and cannot be efficiently simulated. The current VGBA binary has been compiled to be compatible with these demos. In the next version, I hope to use fast read functions that speed up emulation but do not simulate non-aligned reads.
• Older (pre-TS2) development boards from Nintendo had hardware different from the later boards (TS2 and up). VGBA will not correctly run some programs compiled for TS1, such as programs using interrupts.