Todo: Difference between revisions

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* (optionally) display all executed commands when in trace mode ( )
* (optionally) display all executed commands when in trace mode ( )
* improve handling of memory ranges ( )
* improve handling of memory ranges ( )
* Show the VDC registers ($d600-$d601) with IO command (was fixed with revision 20839 but lost since??)
* Show the internal VDC registers (0-36) with IO command

====Sound System====
====Sound System====

Revision as of 13:24, 5 January 2013

Prime Directive

  • when adding/changing stuff that needs (G)UI items/changes, add a proper entry to the Developer_log to notify the UI maintainers.
  • when changing something that needs an update to text messages (and as such, the translation), add a proper entry to the Translator_log to notify the Translators.
  • when adding/changing command-line options and/or resources, adding a new feature or change the behavior of an existing feature, please update the documentation :)
  • after fixing a bug or implementing a new feature, update its status on the Bug Tracker and mark it as fixed in the list below.

Known Issues

This is the list of known problems. also look at Tracker: open Bugs

This list always refers to the status of the last major release version, which was 2.4. Items that have been fixed by the time of a major release will be removed, items fixed after that will be marked as fixed and stay until the next major version. New items will be added as noticed.



  • many nodes are not yet linked correctly, which makes some of the exporters output garbled and/or suboptimal output (windows .hlp, unix .info).

Workaround: use the .html or .pdf documentation, which is exported correctly.


The documentation is partly outdated and/or incomplete, in particular:

  • some descriptions of emulator formats are missing (D67, D1M, D2M, D4M...)
  • descriptions of several snapshot modules are missing (Plus4, TED...)

for details look at doc/Documentation-Howto.txt



  • When a key which is shifted on the real machine but unshifted on the PC or Unix keyboard you are using is pressed, the virtual shift is pressed together (i.e. at the same clock cycle) with the main key; this could not work with some keyboard routines.

note: also see this knowledgebase article:

Workaround: If you have to use the function keys, press the (real) shift key manually (e.g. F2 = Shift + F1, F4 = Shift + F3 and so on); this also works with other keys.

  • Some ports do not have all required keymaps, and the general logic of the keymap resources / commandline options seems inconsistant. (one resource/option per keyboard on the emulated machine, not per keyboard/language combo! - eg -symdekeymap for c64 and associated resource should get removed) also perhaps related:
    • for some ideas of how this could be solved look here: Keymaps
  • Although "shift lock" can be mapped to a key, not all ports and/or emulators support it due to missing keymaps and/or implementation details.



  • When loading a snapshot, the monitor break/watchpoints break.

History Recording

  • history recording currently breaks on a lot of user actions, such as using autostart or attaching a cartridge.

Workaround: make sure to start up with a bog standard c64, and then load/run the program in question manually

note: since history recording is very error prone and hard to debug, we depend on feedback (on either failure or success) on this topic very much. if you still have problems with the current release, please report them including testcases.

Screenshots / Media Recording

  • Screenshots with activated video filter (CRT emulation / Scale2x) do not deliver the expected (filtered) result.


  • some things are still shared by videochips although they shouldnt be, resulting in conflicts for eg the color generation (visible in x128 in ports that show two windows at a time, when crt emulation is enabled, eg adjusting brightness affects also the other window)
CRT Emulation
  • the rf-modulator output characteristics are not emulated, which means the so called "black bleeding" effect does not work (emusux0r,
  • artefact color and luma/chroma crosstalk are not emulated (eg the "red/green stripes")
  • the alternative "sony matrix" for decoding NTSC is not yet implemented

see for some further info on this topic.

Drive Emulation

  • Dual disk drive 2040/3040 support (DOS1, 670 blocks free) is not working
  • when using a dual drive, only the first drive (0:) can be used.
virtual Devices
  • the drive rom can not be read using "m-r" when tde is disabled (instead zeros will be returned).

note: this is actually not a missing feature but a bug - because the code _does_ return the drive rom array, its just not loaded. however, the current situation (returning zeros) should be default for most practical situations - so when this gets fixed, it should be optional. --Gpz 01:52, 11 January 2011 (UTC)

  • handling of CBM style sub partitions is incomplete, write operations on sub partitions may give unexpected results.
True Drive Emulation
  • serial timing latency is not implemented. due to their physical properties, it takes about half a cycle for a value to show up at the respective output pin after it has been written to the register. and respectivly, it takes about half a cycle from changing an input pin until the value in the respective register changes.
  • mechanical delays (such as head stepping and motor spinup) are not emulated yet.
  • 2mhz mode of the 1571 is not handled correctly, 1571 has extra delay on on reading sync inside the drive, ("you cannot use BVC in 2mhz mode!")
  • 1571CR emulation does not work correctly
  • double sided 1571 images do not work correctly
  • when using dolphin dos 3 emulation, the state of the mc6821 is not saved to/restored from snapshots
  • when using supercard+ emulation, the optional additional index hole sensor (for the IHS nibbler) is not emulated
Drive Noise
  • since the current implementation is a very simple sample player, things like "drive composer" will not work

Datasette Emulation

  • unlike with a real datasette, the emulated counter will stop counting when no tape/image is present
  • when a t64 image is attached, the datasette status will incorrectly say "no image".

Note: since t64 is currently only accessable via kernal traps, the datasette emulation actually treats this case as if no image is present. The respective code must be updated so the datasette emulation actually "knows" about when t64 is in use.

  • motor noise is not emulated

Printer Emulation

there perhaps should be a way to explicitly set a directory for printer output files Gpz 01:24, 4 July 2011 (UTC)


unfortunately to fix this a lot of c1541 will have to be rewritten (mount image only once, not for each operation) Gpz (talk) 23:57, 13 December 2012 (UTC)



  • the case when CIA1 port A and port B are both in output mode, port A outputs low, port B outputs high, both are connected via the keyboard matrix and a value is read from port B is not handled correctly ( testprogs/CIA/ciaports ; ) (has been improved but is not perfect)
  • another odd special case is when some bits of a port are programmed as output, others as input. and then they are connected via the keyboard matrix by pressing several keys at once. this is not emulated yet at all. (added in r26551)
  • the various analog side effects that must be considered when pressing two or more keys are not emulated correctly, so this will currently not produce the correct results in some corner cases.

used in: C64, C128


  • the POTX/POTY sampling period is not taken into account
  • POTX/POTY sampling jitter is not emulated
  • only one mouse or pair of paddles can be emulated at a time


used in: Plus4


Workaround: use the "default" palette.

used in: C128


used in: VIC-20


used in: C64, CBM2


  • The test bit is not emulated, which results in things like 'real interlace' ([1]) not working.

used in: C128


  • 48bit frames support is incorrect/broken
  • synthesizer condition 2 loss-effect-, shape- and repeat- bits have no effect
  • reading from the speach rom is not emulated (which is not really an issue since neither magic voice nor v364 have one)
  • snapshot support is missing

used in: Magic Voice, Plus4 (V364)


  • interrupts are not implemented
  • implementation of C2 output modes is incomplete

used in: Formel64, Magic Formel, Dolphin-DOS 3


  • snapshot support is missing

used in: RR-Net/TFE



  • snapshot support is missing

used in: MMC64, MMC Replay


  • snapshot support is missing

used in: MMC Replay


  • snapshot support is missing

used in: C64, VIC-20



  • at startup vsid still loads a keyboard map (not really a problem, but probably shouldnt happen anyway :)) (fixed in r26914)

x64 / x64sc

  • "Max Machine" and "C64 Game System" models are missing
x64 issues addressed by x64sc

To clarify... these will never (as in can't) be emulated in the regular x64, unless we end up replacing x64 with x64sc.

  • some VIC-II bugs present in the old VIC-II core
    • inline gfx data changes are not emulated (see testprogs/VICII/gfxfetch/)
    • The VIC-II implementation lacks cycle exact sprite collision support
    • VIC-II shows wrong colors when switching from hires background to idle with borders open (see testprogs/VICII/border/*, Krestology)
    • VIC-II fetches from cartridge in ultimax mode can not be emulated properly for all carts

note: this is also broken in xcbm2

Workaround in all cases: use x64sc :)

x64 specific problems

note: While most of the x64sc improvements/fixes are impossible to shoehorn into x64 (hence the split), a few things could still be improved:

Workaround in all cases: use x64sc :)

Cartridge System
  • some carts have no snapshot support yet (still broken: MMC64, Magic Voice, MMC Replay, MIDI, Ethernet.)
    • IDE64 & ATA system can only handle "readonly" snapshots now. Somehow the image file must be matched to the snapshot to prevent corruption.
  • some carts do not work 100% yet (still broken: KCS, Magic Voice, MMC Replay.)
    • KCS: BLOADing a frozen program does not work
    • Magic Voice: emulation of the speech chip is incomplete (see Todo#t6721a), this breaks some words included in the magic voice rom and the "a-bee-c" cartridge. Memory mapping is incomplete/broken (which however affects no known software/testcase).
    • MMC Replay: only the BIOS mode works right now; the monitor may incorrectly access cartridge memory (even) if "bank cart" is explicitly set
  • IDE64 shortbus expansions not emulated
  • SFX sound sampler audio input is not emulated
  • various cartridges have no support for verbose i/o dump in the monitor
  • Passthrough port functionality depends on ordering of cartridge attaches, especially visible from the command line. (e.g. MMC64+RR ok, RR+MMC64 not)

note: the detailed todo list/status is here.


  • Support for fast mode (2MHz) is implemented but incomplete, detailed information about the stealing of cycles by the VICII when switching back from fast mode is missing and therefor the emulation of it is incorrect.
  • support for c128 specific expansion port handling/mapping is missing in the c64/c128 cartridge system (MMC Replay, FastLoad128, MACH128, other?)
  • the relative speed and details like cycle-stealing of the z80 is inaccurate ( ) TODO: cycle accurate test programs




The plus4 emulator is generally work in progress and not yet "ready". Maintainer wanted!


  • The CBM-II emulator, when the execution bank is set to an open memory bank, sets the zeropage and stack access to unmapped, but actually existing memory. This is a bug but cannot be avoided with the current CPU code architecture.
  • break- and watchpoints in zeropage are broken. this is because of the old cpu core, and can likely not be fixed without migrating to the new one.
  • banking in the monitor is broken
  • when running the burn-in diagnostic tests, the CIA is reported as bad ( )

note: run like this: xcbm2 -model 610 -ntsc -drive8type 8050 +truedrive -8 cbm2-burnin.d80


  • The emulator, when the execution bank is set to an open memory bank, sets the zeropage and stack access to unmapped, but actually existing memory. This is a bug but cannot be avoided with the current CPU code architecture.
  • break- and watchpoints in zeropage are broken. this is because of the old cpu core, and can likely not be fixed without migrating to the new one.
  • banking in the monitor is broken
  • In the C510 emulation the VIC-II timing is not exact, i.e. the stopping of the CPU during bad lines is wrong.
  • The C510 emulation uses the old VIC-II core which means no cycle exact sprite collisions, no inline gfx changes, and probably more.


  • When running the "8296d diagnostic" test of the 8296 system disk on "xpet -model 8296" some tests fail:
    • when TDE is enabled, the program will hang. when TDE is disabled, the IEEE interface status will be reported as bad
    • the userport is reported as bad (perhaps some dongle is needed?)

note: run like this: "xpet -model 8296 -drive8type 8050 -8 8296d-systemdisk.d82 -editor edit-4-80-b-50Hz.901474-04.bin". the "burnin8296" program seems to be an older version of the "8296d diagnostic" program. it runs when TDE is enabled, but the 50Hz irq test fails.

  • break- and watchpoints in zeropage are broken. this is because of the old cpu core, and can likely not be fixed without migrating to the new one.
  • some combinations of selected keymap and keyboard model do not work because of missing keymaps

Ports / UIs

  • In the C128 emulation VIC-II and VDC palette can not coexist currently in some ports. (unconfirmed: beos, osx)
  • The CBM-II emulation is not fully supported in all ports. (unconfirmed: beos, dos, osx)
  • VSID is not fully supported in all ports: (unconfirmed: beos, dos, osx)
  • YUV rendering (used by amigaos and xaw) implementation is incomplete
    • scale2x not available
    • some renderers are missing
    • doublesize + y-stretch (2x4) doesnt work correctly


Win32 DX9
  • There is a bug when moving the window partly outside the left edge of the screen. The rendered contents seem to "lock" to the left border. This seems to depend on the driver of the gfx adapter as is only shows on some machines.
Windows 7

X11 (XAW and GTK)

  • The custom TextField widget is buggy and can cause crashes on DEC/Alpha machines, and possibly on other systems too. If you get weird X protocol errors or the file selector makes the emulator die when you close it, this might be the cause.
    Workaround: recompile with the `--disable-textfield' option. If it still does not work, please tell us.
  • some text output may show broken characters for "foreign" UTF8 chars due to improver conversion (please report such cases!)
  • lightpen coordinates are not accurate when using vidmode for fullscreen
  • mouse warping when using vidmode for fullscreen is buggy
  • the mouse pointer is incorrectly un-grabbed when switching from/to fullscreen with the mouse- or lightpen emulation enabled.
    Workaround: use XRandR for fullscreen
  • Gnome/GTK+ commandline is ignored.
  • the event handling is buggy, which results in some more or less broken behaviour eg when holding down ALT-D or ALT-B (the later in fullscreen mode)
  • lightpen (x) coordinate is broken

TODO: write proper test program

  • Some DEC/Alpha machines crash due to the XAW implementation.
    Workaround: Compile VICE with GNOME support `--enable-gnomeui' instead.
  • warning "Files using this header must be compiled with _SVID_SOURCE or _XOPEN_SOURCE" may show up if none is defined in the environment
    Workaround: define _XOPEN_SOURCE=600 on the commandline
  • Context popup menu for drive attach is broken if more than two drives are active.
  • when hardware rendering is enabled, greenish color might appear around the drawing area.
  • Aspect ratio/scaling is broken in fullscreen mode when hardware rendering is enabled (canvas is always stretched to fill the entire screen)
  • the mouse pointer is incorrectly un-grabbed when switching from/to fullscreen with the mouse- or lightpen emulation enabled.
  • mouse- and lightpen emulation/coordinates are broken on the second window (VDC/x128)


  • In the MS-DOS port you have to save the configuration and restart the emulator when changing VDC double size mode.





  • Sometimes the application loses the keyboard focus; no keystrokes are accepted inside the emu, so the emulator has to be restarted.
  • Sound problems on slower machines (P100) with a non-official driver for sb16.
  • The monitor only works if you start the emulator from a terminal; if you start the emu from tracker and enter the monitor, you are "lost"
  • Fullscreen mode is not implemented.


  • The GP2X port segfaults at start.

note: this port is unmaintained and because of that subject for removal.

  • uses preset sdl-vicerc files which are unmaintained and thus could fail. At least sdl-vicerc-cbm5x0 is obsolete and broken due to the config split.

note: this port is unmaintained and because of that subject for removal.

External Libraries

VICE uses a few external libraries of which either header files or complete sources are included in the tree:

  • opencbm (src/opencbm.h) (
    • should get moved to src/lib/..
  • P64 (src/lib/P64)
  • ffmpeg (src/lib/libffmpeg)
    • since ffmpeg has a long history of API breaking it might be a good idea to include the entire library in the tree and link it statically

besides the above, other libraries are used which are currently linked dynamically and must be supplied as dlls for the windows port

  • SDL
  • zlib
  • hardsid


  • The "sc" rewrites. Migrate emulators to the cycle based CPU core (6510dtvcore.c, should be renamed), which allows:
    • cycle based hooks for complex hardware expansions (SCPU)
    • in-line graphics data change emulation (see testprogs/VICII/gfxfetch)
    • cycle exact Blitter/DMA vblank start and proper LinearA/B counter handling on x64dtv
    • cycle based drawing
  • ...and requires (at least):
    • rewrite video chip modules to use:
      • cycle based fetch/etc (VIC & VICII done, VICII-DTV in progress)
      • cycle based drawing (VICII done)
    • remove 1 clock write offset in CIA etc (at least CIA/VIA already handled in trunk)
    • an insane amount of regression testing (preferably with new testprogs where needed)


  • Update the *nix documentation
    • perhaps find a way to conditionally include arch specific stuff in vice.texi ?
  • proper and specific win32 documentation. (.chm format)
  • proper and specific amiga documentation. (.guide format)
  • proper and specific BeOS documentation.
  • proper and specific MSDOS documentation. (.txt format)
  • proper and specific OS/2 documentation. (.inf format)
  • proper and specific RiscOS documentation.
  • proper and specific SDL documentation.


  • Support for more languages.
  • Translation support for BeOS.
  • Translation support for MSDOS
  • Translation support for OS/2

Ports / GUI improvements

  • Make a list of GUI elements/features per port, compare and implement any missing features for the ports. ( Gui cleanup )
  • Make a list of Hotkeys used per port, compare and try to make them the same / alike. ( Hotkey cleanup )
  • Debug/fix the XBOX SDL port.
  • Debug/fix the Windows-CE SDL ports.
  • Completely update the GP2X GUI.






  • amount of random auto start delay can not be changed using the GUI (AutostartDelay) (added in r26682)
  • the initial window and canvas should be created using its final size and not resized later


  • add Session Management
  • improve Tape status widget, (.TAP vs .t64 handling is lousy.)
  • implement actual Monitor GUI (like in the windows port) ( )
  • start c1541 inside a VTE terminal window and not use an xterm
  • improve/fix widget layout in "save media image" dialog
  • improve/fix widget layout in "netplay" dialog
  • doodle output driver options are missing in "save media image" dialog (DoodleCRTCTextColor, DoodleTEDLumHandling, DoodleMultiColorHandling, DoodleOversizeHandling) (added in r26901)
  • in the crt setting dialog, options that are not available in the current config should be made inactive. (added in r26708)


  • add "commandline options" help window (like in the windows port)
  • hide hidden files (dot files) in the filebrowser ( )
  • implement "edit" (copy/paste) menu
  • add Drag'n'Drop support
  • the status bar area of the created window is larger than it should be
  • ffmpeg half frame-rate setting missing in "save media image" dialog (FFMPEGVideoHalveFramerate)
  • sound volume can not be changed using the GUI (SoundVolume)
  • datasette status widget is not implemented


  • add PCI support for catweasel and hardsid


  • add real IEC device support via par port or ser port
  • add proper lfn detection

New Features

This is the place for the VICE developers to put down ideas about the future development of VICE.

Some of these ideas might never be realized, and might look completely absurd, but they could be the inspiration for other ideas.

By putting these ideas down they will be known to any other developers that would like to pick up one of the ideas and implement it.

also look at Tracker: open Feature Requests


History Recording




Sound System

  • some kind of generic interface to handle audio input is required to handle sampler carts

Video System

  • some kind of generic interface to handle video input is required to handle scanner/digitizer type of carts

Hardware emulation



  • internal (?)
    • c64/c128 1.44 MB disk drive support. ([2])
    • c64/c128 SCSI expansion support. ([3])
  • Cartridges
    • IDE64 improvements
      • IDE64 eth64 shortbus expansion support. ([4])
      • IDE64 duart shortbus expansion support. ([5])
    • SFX sound sampler improvements
      • SFX sound sampler audio input support. ([6])
    • Clockport improvements
      • Silversurfer (UART) support ([7])
      • mp3@c64 support
      • IDE64 based eth64-II support ([8])
    • Community Information Locator Commodore 64/128 addon cartridge ([9])
    • RAM Floppy (REX 9680) support
    • Daisy Sound sampler audio input support. ([10])
    • PS64 speech cartridge support. ([11])
    • Voice Messenger speech cartridge support. ([12])
    • ramlink support. ([13] [14])
    • ramdrive support. ([15])
    • z80 (cpm) cartridge support. (4Mhz z80)
    • turbo master cartridge support (4Mhz 65C02). ([16] [17])
    • turbo process cartridge support (4Mhz 658156). ([18] [19])
    • flash-8 cartridge support (8Mhz 65816). ([20])
    • SCPU cartridge support (20Mhz 65816). ([21] [22]) (
    • The Final Chesscard (65c02) ([23])
    • german BTX cartridge (6809)
    • SoftPROM cartridge ([24])
      • pointless, unless software specifically designed for this cart can be found. other than that its just an ordinary 8k game cart (with battery backed up ram instead of rom). Gpz 23:01, 30 October 2010 (UTC)
    • Net64 cartridge support. ([25])
      • this is exactly the same as "the final ethernet" (which is emulated) Gpz 23:27, 30 October 2010 (UTC)
    • 64NIC
      • again, same as TFE. also has an optional eprom, which is equivalent to using cart8
    • MasC=uerade Cartridge Converter support, this cart is originally intended to use c64 carts on the vic20, but in theory could also be used the other way around. ([26])
    • BI-80 cartridge support. ([27])
    • Buscard II IEEE488/printer-port cartridge support. ([28])
    • "GeoAction"
      • pointless, equivalent to Action Replay + GeoRAM/RamCart
    • "Flash Gordon"
      • pointless, external kernal with flash, prototype (not released)
    • "Disk Mate" (Datel)
    • MAYA Software Eprom Cart
    • PCC-4/PCC-8 Eprom Cart (Jason Ranheim)
    • "Alien Flash"
  • Userport
    • CBM1660 (userport) modem300 support. ([29])
    • CBM1670 (userport) modem1200 support. ([30])
    • FB-RS232 (userport) support. ([31])
    • c64 p64 midi interface: ([32])
    • Scanntronik handyscanner (userport) support. ([33])
    • Video Byte II video digitizer (userport) support. ([34]) ([35])
    • Computera Eyes video digitizer (userport) support. ([36] [37])
    • Userport RocketDrive support. ([38])
    • CIA-IDE-HD support. ([39])
    • Aprotek universal rs232 adapter support. ([40])
    • Comet64 support. ([41])
    • L. Pantarottos adapter support. ([42])
    • Amiga mouse emulation on 4-player adapters. (
  • Video output.
    • c64 LCD64 screen support. ([52])


  • c128 plus60k support.
  • c128 plus256k support.
  • c128 256K memory expansion hack support.



  • plus4 digiblaster audio input support. ([56])
  • add support for "speedy" freezer cartridge


  • PET ROM-socket RTC support. ([57])
  • 8296 pet hardware ram lines connected to userport support.
  • 8296 RAMdisk 2008 support. ([58])
  • 8296 pet switchable 4 screens output support.
  • pet IEEE488 -> IDE/RS232 support. ([59])
  • High-Res Technologies Graphics Board support. ([60])
  • MTU K-1002-2 DAC sound system support. ([61])


  • cbm2 z80 support.
  • cbm2 8088 support. ([62])




new Ports

  • windows-ce X11 support.
  • amiga X11 support.
  • RiscOS X11 support.
  • Port to Plan9
  • Port to win16
  • Port to win32s (maybe by using windib)
  • Port to mips windows nt
  • Port to alpha windows nt
  • Port to ppc windows nt
  • Port to windows-ce
  • Port to macos classic (8.x/9.x).
  • Port to VersaDOS
  • Make OS/2 SDL port.
  • Make atari mint SDL port.
  • Make macos classic SDL port.
  • Make dreamcast SDL port.
  • Make GP32 SDL port.
  • Make PSP SDL port.
  • Make WII SDL port.
  • Make PALMOS SDL port.
  • Make GBA SDL port.
  • Make NDS SDL port.
  • Make PS2 SDL port.
  • Make GameCube SDL port.
  • Make VAX OpenVMS SDL port.
  • Make ALPHA OpenVMS SDL port.
  • Make HPPA OpenVMS SDL port.
  • Make Symbian OS SDL port.
  • Make XBOX360 SDL port.
  • Make Ipod/Iphone SDL port.
  • Make android SDL port.
  • Make pandora SDL port.
  • Make caanoo SDL port.
  • Make wiz SDL port.
  • Make GP2X SDL port with proper joystick/pad handling.
  • Make zodiac SDL port.
  • Make webOS SDL port.