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Prime Directive

  • when adding/changing stuff that needs (G)UI items/changes, all developers should update the SDL and GTK3 UIs themselves, and immediately following their respective changes.
  • 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.
<@_tlr> Please at least test the issue you were trying to fix before committing.

Code cleanup and streamlining

As of 3.2 we will remove a lot of the old cruft, that was dangling around in the tree for way too long, to make maintenance easier

  • remove all GUIs except the GTK3 and SDL UIs
  • remove translation support (SDL and GTK3 do not have any support for this, so this applies mostly to the command line help)
  • remove compiler- and platform- specific hacks (IFDEFS) in common code
  • merge archdep* files of SDL and Gtk3 into src/archdep/ (so the same code is used for GTK3 and SDL)
  • remove the YUV rendering code, its broken and archaic and shouldnt be needed anywhere
  • add howto into docs dir for gtk3 building (needs windows/linux/osx specific instructions)
docs for Linux and Windows (msys2) are there, OSX is still a mystery
  • remove COMMON_KBD (or better things in #ifndef COMMON_KBD - formerly used by OS/2 and BeOS)
  • remove the third scaling method described in Scaling_cleanup (formerly used by XAW)
  • add proper Icons to both UIs
TODO: update the Icons page with all required info
  • revisit the old Feature checking pages, and clear it out eventually
  • make a configure option to enable building of x64. this should be OFF by default (and desktop binary distributions should not include it)
  • update checkdoc script(s) and make sure the manual is up to date and has all resources and options for GTK3/SDL

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 3.2. 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.


MAN Pages

  • the man pages are very outdated and should perhaps be generated from the infotext
    • the man pages refer to the path where the html documentation can be found, this should get adjusted to whats actually used
  • the following man pages are missing: vsid
  • man pages for the individual emulator binaries should get installed as symbolic links to vice.1


  • 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 info that was previously hidden in target specific articles on the VICE knowledge base should get merged into vice.texi - the remaining articles are here
  • some descriptions of emulator formats are missing (D67, D1M, D2M, D4M...)
  • descriptions of several snapshot modules are missing (Plus4, TED...)
  • generate target specific documentation
    • win32 documentation. (.chm format)
    • amiga documentation. (.guide format)
    • BeOS documentation. (.html format)
    • MSDOS documentation. (.txt format)
    • OS/2 documentation. (.inf format)
    • RiscOS documentation.
    • SDL documentation.

for details look at doc/Documentation-Howto.txt


  • many test programs (mostly for vic20) are not yet integrated into the automatic testing
  • TODO: fix the reference screenshots and/or the scripts so they dont rely on the "normal" rendering mode anymore
  • TODO: make a test program to determine visible screen dimensions



  • 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.
  • When typing very quickly, some keypresses might get lost. This comes from the fact that the keyboard is (and can not) be scanned in real time (ie every 1mhz cycle). Even if we could remove the per frame scanning from the emulator itself, the operating system and last not least the keyboard itself would still impose a certain limit (something like 10ms for USB HID keyboards, for example). That means if a key is pressed and released within that timespan, the emulator does (and can not) know about it.
Workaround: the only workaround is to type slower, it cant be fixed.
  • Some ports/emulators/keyboard-types do not have all required keymaps (and a fallback will used) - look at Keymaps for details
  • 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.
TODO: check ports and fix or at least add a comment in the keymaps
  • contact-bounce is not emulated
TODO: make a proper test program


TODO: make a proper test program

Joystick port devices

  • Paperclip 64 dongle emulation is broken


  • some options where the available parameters depend on the machine type lack proper descriptions (-drivetype)


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

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)
  • TODO add a 4:3 fixed aspect ratio scaling mode
  • TODO when a test program has been written, adjust the "normal" border mode accordingly (CAUTION: fix testsuite first)
  • TODO put all border mode parameters into arrays, make a global function to query the parameters and modes (for UIs) and then add "TV" mode (like "normal", but not centered)
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")
  • color generation should get a partial rewrite according to new research by pepto (

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, and no TDE, only the first drive (0:) can be used.
  • G64 image support is incomplete, the speedzone definitions are completely ignored
Note: this is no problem in practise, so far not a single title (game) could be located that would actually require this kind of support to work. Incase you find a program that needs this kind of support, please let us know.
  • RPM and Wobble settings have currently no effect when P64 images are used
virtual Devices
  • handling of CBM style sub partitions is incomplete, write operations on sub partitions may give unexpected results.
  • RELative files are only supported when using disk images ( )
  • support for double sided disk images is very shaky, since no concept of disk sides exists and the tracks on the second side are referenced by an offset into the image, the handling of images with different number of tracks is needlessly hard and complicated (and thus broken).
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.
  • accessing device #7 on the IEC bus works (only real devices), but it only works if True Drive Emulation is OFF, even though this has nothing to do with drives. This needs to be fixed in TDE somehow.
  • 1541 Emulation still fails a few test programs
  • 2mhz mode of the 1571 is not handled correctly
    • drive CPUs always run at 1Mhz for all drives (hardcoded 1000000 at a few places)
    • 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
    • regular (70 tracks) vs extended (80 or 84 tracks) d71 images are not handled at all (vdrive problem)
    • creating (formatting) G71 does not work correctly, the second BAM block will be wrong (vdrive problem)
    • double sided P64 can be used, but can not be created from within VICE (see patch #122, r32586). since these are non existant "in the wild" and probably not needed for anything - not a big problem :) to handle this properly, a seperate image format should get created (at least internally)
Dual Drives

r25459 by Rhialto:

I enabled up to DRIVE_NUM IEEE-488 drives, rather than 2 (in True Drive Emulation mode). In some places where they are enumerated, it is 4. The drives use their full 3 bits of jumpered drive number now, rather than just 1 bit.

I have also generalised code so as to allow another dual drive. Since dual drives currently use up two device numbers, it will use 10 and 11. I'm currently simplifying the methods for checking the dualness of a drive.

When that is done, I hope to have gained enough understanding of the code to remove the horrible hack of using 2 devices for a dual drive, and remove it. It looks like it will simplify a lot of code (including removing lots of code that I changed for allowing 2 dual drives). That will have some repercussions on the GUIs, since for every drive you may need to be able to attach two image files. It also would add an extra "drive" parameter (in addition to the current "unit" parameter) to a shedload of functions, although this is a pretty mechanical change. In fact, it is the GUI change that currently holds me back...

TODO: Think of some elegant way to represent settings for 8 floppy images (for 4 dual drives), without requiring all GUIs to be updated at once.

TODO: After that, I can rework the code to make dual drives more regular and hence allow 4 of them.

  • 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

Tape port devices

  • DTL Basic Dongle emulation is broken

Printer Emulation

there perhaps should be a way to explicitly set a directory for printer output files Gpz 01:24, 4 July 2011 (UTC)
  • printer noise is not emulated
  • printers don't work on the PET (or other IEEE-488 computers)


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)
  • 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.
  • Shift Register IRQ triggers only cycle too early (see this bug)
  • I/O "peek" function is broken

used in: C64, C128, 1570/71


  • we need different tweak values (filter bias etc) for 6518 and 8580
  • the POTX/POTY sampling period is not taken into account (512 cycles)
  • POTX/POTY sampling jitter is not emulated
  • only one mouse or pair of paddles can be emulated at a time
  • 'dump' support in the monitor is missing

used in: C64, C128, CBM2, (VIC20, PLUS4, PET: SID cart)


used in: Plus4


  • Some basic features of the VDC are missing:
  • Registers 34/35 (horizontal blanking position) not implemented
  • $d600 bit 7 STATUS flag is only approximately implemented. Fixing requires emulating the internal timing of the VDC.. (partially implemented in r35456, also see testprogs/VDC/vdctiming)
  • Differences between 8563 and 8568 are not all emulated, eg. register 38
  • Snapshot doesn't include VDC
  • Clock calculation for lightpen is incorrect

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]) and the $D030 new VIC-IIe color palette hack ([2]) 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


  • I/O "peek" function is broken
  • I/O "dump" function is missing

used in: 2040/3040/4040/1001/8050/8250


  • I/O "dump" function is missing

used in: FD4000/FD2000


  • I/O "dump" function is missing

used in: 1570/1571/1581



  • 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



x64 / x64sc

  • the memory layout for "Max Machine" is not yet correct
  • when SX-64 is selected, the tick for the CIA TOD clocks should always be 60Hz (regardless of PAL/NTSC)
  • for details see C64models
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

note: the detailed todo list/status is here.

  • some carts have no snapshot support yet (still broken: MMC64, Magic Voice, MMC Replay, MIDI, RR-Net MK3, 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: Magic Voice, MMC Replay.)
    • 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
    • RR-Net MK3: to get the ethernet functionality it must be explicitly enabled too, and will appear as a "clockport" internally (which is wrong)
  • the (very strange, and incompatible with most cartridges) passthrough port of the SFX sound expander 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)


  • 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
  • CPU history (chist) implementation is incomplete



The DTV emulator is very inaccurate and is in need of a partial rewrite. Maintainer wanted!


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
  • breakpoints are broken
    • when a breakpoint is hit, the monitor disassembles from the wrong bank
    • breakpoints will only hit in the bank which is active in the monitor (!)
  • when running the burn-in diagnostic tests, the CIA is reported as bad ( )
note: run like this: xcbm2 -model 610 -ntsc -drive8type 8050 -virtualdev +truedrive -8 cbm2-burnin.d80
  • CPU history (chist) implementation is incomplete


  • 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.
  • CPU history (chist) implementation is incomplete


  • 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
  • CPU history (chist) implementation is incomplete


  • Make a list of Hotkeys used per port, compare and try to make them the same / alike. ( Hotkey cleanup )
  • enable/disable menu items in drive settings menu according to Drive_options_precedence
  • Fix all Keymap handling according to Keymaps





  • Sound problems on slower machines (P100) with a non-official driver for sb16.
  • Compiling with `--enable-ethernet` fails due to absence of rawnetarch.{c,h} missing --Compyx 2016-10-26 (tested on Haiku)

Archdep cleanup

  • merge GTK3 and SDL archdep code
    • remove use of GLib code so the Gtk3 archdep code can be merged with SDL archdep (which doesn't use GLib for obvious reasons)
  • make sure VICEDIR, DOCDIR, LIBDIR etc (add here) are NOT used in common code (ONLY archdep)
    • create functions to retrieve the respective pathes instead
      • make sure common code uses these, ie no magic fiddling with archdep_boot_path() per platform (except in archdep)
  • make sure common code ONLY includes archdep.h, not archapi.h


The how and why we go Gtk3 for *nix, Windows and OSX should be clear, but I'll reiterate: since we don't have any Windows or OSX maintainters left and failed to attract new ones, the decision was made to use Gtk3 as the new UI for 'modern' OSes.

Gtk3 is portable and widely supported and has a C interface. So we should be able to write the UI code once and have it run on our major platforms: Linux, Windows and OSX. Using GLib (a dependency of Gtk3) a lot of platform-dependent code in the UI can be avoided and many standard dialogs, such as open/save/select-dir need to written only once, Gtk3/GLib will handle most of the platform-dependent stuff.

Current development state

  • All emulators work, though some UI code still needs to be written or updated to properly support all machines
  • Default renderer is OpenGL 3.2 based (GTK 3.16 required) and does full HW scaling. Fallback renderer is Cairo-based, which will scale in software if necessary but slows down noticably when it does.
  • All UI code is hand-written, we tried using Glade/GtkBuilder, but the amount of machines and extra hardware VICE supports is way too much what a static UI can handle
  • Though many UI elements look okay, some don't. This isn't lazyness but rather to avoid tweaking the layout only to discover later that it still needs to be changed. So any layout/style issues will eventually get fixed. So don't complain about it, unless there are glaring bugs (such as dialogs that are too large to fit on a decent screen)
Unix (Linux)

./configure --enable-native-gtk3ui

  • starts up, video, audio, keyboard, joysticks, mouse working

./configure --enable-native-gtk3ui

  • starts up, video, audio, keyboard, joysticks, mouse working
  • TODO: make joystick input work [3]
    • TODO: some stuff is commented out in joy-win32.c and joy-win32-dinput-handle.c
  • TODO: make mouse input work
  • untested

./configure --enable-native-gtk3ui

  • TODO: make it compile and start up
  • TODO: make video and audio work
  • TODO: make keyboard work
  • TODO: make joystick input work
  • TODO: make mouse input work
    • mouse grab doesnt seem to work, also the provided POTX/Y values seem to be seriously laggy. mouse buttons and scrollwheel DO work however


This is a list of things to do and bugs to fix. This is no way an exhaustive list, to get a better understanding of what needs to be fixed/altered, run this command inside VICE's top dir: grep -n 'FIXME\|TODO\|XXX' `find src/arch/gtk3 -name '*.c'`, and be amazed.

  • Mouse-grab. The UI items is there, but the actual mouse code isn't implemented yet (2017-11-08)
Works fine on Linux, tested it with a hacked Amica Paint and an emulated 1351 mouse (compyx, 2018-05-30)
  • The Tape Devices widget needs to check if resources can be set to avoid segfaults (2017-11-14)
  • the statusbar Drive widget is missing the directory popup, fliplist UI and a couple other options that existed in the gtk2 ui
  • the statusbar Tape widget is missing the "directory" popup that existed in the gtk2 ui
  • make sure both hard- and software rendering match whats described in Scaling_cleanup - if so, the page can be cleaned out
  • respect "true aspect ratio" option (currently always off)
  • respect "keep aspect ratio" option (currently always on)
  • save/restore window(s) size(s) and position(s) from vice.ini
    • do not forget the VDC and the Monitor windows
  • hotkeys - preferably user configureable (like SDL)
  • statusbar (see uistatusbar.c for some comments) (Mostly done, needs a bit of love still)
  • mixer and CRT-emu control
like the existing widget with the sliders in the gtk2 port, put split into two separate widgets of which one only has the audio related (mixer) and the other the video related (CRT) stuff
Both CRT and mixer controls have been added, with checkboxes in the statusbar widget to enable/disable them. Still requires a bit of refactoring to properly manage fullscreen when using the dual-display x128 emulator. (compyx, 2018-05-30)
  • the logo/icon/s)/font(s) in about dialog should be embedded using GResource
    • data/fonts and data/logos should go to data/common
    • TODO: add vice.gresource to install/bindist
    • TODO: load the CBM font for the file selector from vice.gresource this is not possible, now using fontconfig on Linux and GDI on Windows. MacOS needs testing, it might support fontconfig, but we'll probably have to use whatever API MacOS uses.
  • eg seen in vsid/change hvsc root: open settings, change the path BY TYPING something (with "browse" it works), then save settings and/or leave settings dialog. the resource wont be changed
  • when browsing to select a directory, make it so that files are not shown at all (not just greyed out)
  • there is no commandline to set fullscreen mode (ie -VICIIfull, +VICIIfull etc...) and no resource ("VICIIfullscreen"...) either. "UseFullscreen" seems to be used (read) but not assigned?
  • "advance frame" should be inactive when emulation is not paused
  • The model widget is missing a lot of glue logic: when for example switching the C64 model, VICE will update its SID/VICII/CIA models and reset, but this is not reflected in the UI.
  • Perhaps the "show menu/statusbar when fullscreen" menu item should be check button?
  • The "Speed" page in the settings UI is missing widgets to set custom refresh rate and custom emulation speed. (these are available in the popup menu of the CPU/FPS statusbar widget)
  • The PET/CBM-II UI's are missing tape port device settings.
  • The CBM-II UI's are missing RS232 settings.
  • mouse grab (when mouse emulation is enabled) is not perfect. eg when the emulator is started with mouse enabled, the pointer is not initially moved into the emulator window.
Unix (Linux)
  • an archdep function joystick_ui_get_next_device_name should be created which returns a list of extra joystick devices
  • FIXME: The Unix port uses the XDG specification for the vice configuration files, so now `vicerc` is located in `$HOME/.config/vice`, not `$HOME/.vice`. Right now the 'autostart-${emu}.d64' files are also stored there, which is not quite correct.
  • TODO: test mouse -emulation and -grab
  • TODO: the MIDI settings widget should show a combobox with supported drivers
  • in the HELP menu the "browse documentation" item is non functional. we either need a portable solution, or use archdep code here
    • its implemented now using the method recommended for GTK3. needs to be checked on windows and OSX. after 3.2 the "htmlbrowsercommand" resource can be removed.
    • TODO: find out why it uses internet explorer and not the default browser for html
  • GSettings schema files aren't loaded, so things like GtkFileChooser cause an abnormal exit, which means attaching disk images doesn't work.
  • joystick_ui_get_next_device_name should return the detected joysticks instead of the predefined list
  • TODO: test mouse -emulation and -grab
  • TODO: the MIDI settings widget should show a combobox with supported drivers
  • TODO: Add QuickTime recording settings widget, like the FFMPEG recording settings widget
  • FIXME: The Unix port uses the XDG specification for the vice configuration files, so now `vicerc` is located in `$HOME/.config/vice`, not `$HOME/.vice`. Right now the 'autostart-${emu}.d64' files are also stored there, which is not quite correct.


as in using it in the "chars" section of an `m` command, good luck with that with current vte.
  • in the novte lib, GValueArray should be replaced by GArray
forget about that, really screws with the C++ crap. Until we find a better way, the novte stuff will have to do.

for some info on the monitor ui see: MonitorUI.


  • The OpenGL renderer should transform itself into a Cairo renderer if the system doesn't support OpenGL. (2017-11-15)
  • Do-not-scale option. Important for Cairo renderer, possible for OpenGL. (2017-11-15)
  • Stretch goal: the OpenGL renderer should fall back to legacy mode (the SDL renderer) if GTK3 itself has, instead of failing. (2017-11-15)


The list of covered resources is here

  • xpet: "model settings" - more glue logic is needed (2017-11-21)
  • ROM settings are missing (partially supported, needs work (2018-01-31)
  • using scroll wheel on tree view should scroll up/down
Works for me with Debian 9.3 64-bit with Xorg and the MATE desktop (compyx, 2018-05-25) yes, fine here now Gpz (talk) 01:36, 19 June 2018 (CEST)
  • Monitor Settings -> "KeepMonitorOpen" resource does not exist (should probably be created in the yet to do monitor UI code)
    • "NativeMonitor" (-nativemonitor) needs to be implemented too
  • HardSID settings are missing
  • remember last used settings page and reuse that when opening settings again

Drive settings

  • the "IEC device" checkbox should probably be moved to distinguish it from the device list abovee it
    • the resource actually switches on a C-level IEC device on that device number that is used to talk to vdrive/fsdevice/opencbm
  • enable/disable relations should be checked, e.g. selecting "None" as drive type should not grey out IEC device and changing fsdevice settings only makes sense if IEC device is checked
  • presenting vdrive/fsdevice/opencbm as additional radio buttons would make sense from a user's point of view, but is contrary to how the related resources work internally

C64 Cartridge settings

  • MMCR - cartridge image and EEPROM image is mixed up. only the filename selection is related to the EEPROM, the other stuff is related to the cartridge image/flash ROM. also "make eeprom read/write" checkbox is missing. (take GMOD2 as an example, its correct)
  • check I/O extensions for proper behaviour:
    • Memory Expansion Hack
      • BUG: enable one hack after the other from left to right, then go back from right left -> crash (i cant reproduce this anymore, WTF Gpz (talk) 00:15, 13 May 2018 (CEST))
        • ok, it doesnt seem to be a gui problem, crashes in plus256k.c:329 or c64_256k.c:441
    • GEO-RAM
    • RAM Expansion Module
      • BUG: can be enabled but not disabled after that
    • RamCart
    • Double Quick Brown Box
      • BUG: can be enabled but not disabled after that
    • Expert Cartridge
    • ISEPIC
    • EasyFlash
    • GMod2 (I played Sam's Journey with this, so this probably works --compyx)
    • IDE64
    • MMC64
    • MMC Replay
    • Retro Replay
    • Super Snapshot V5
    • Ethernet Cartridge
    • RR-Net Mk3
    • IEEE-488 interface
    • Magic Voice


  • "File->Netplay" needs some testing and refactoring. perhaps move it into settings?
    • Work is under way in uinetplay_new.c, which mostly works but needs the client/server mapping of keyboard/joystick etc. And indeed moving into settings would be prefered (compyx, 2018-02-09)
  • Many open/save dialogs could be improved by remembering the last used directory. Already done are 'smart-attach', 'cart-attach' and 'disk-attach'. (compyx, 2018-05-12) Done. If any dialogs still need it, let me know.

Media recording

  • Implement audio recording and video recording (2017-12-17)
    • Mostly implemented, what is missing is a 'stop recording' button on the status bar (compyx 2017-12-23)

Upstream bugs

  • Some combobox contents appear to have 'empty' entries and sometimes the colors of the items change (upstream Gtk3 bug) (2017-11-08)

Feature requests / Stretch goals

  • Add some way to show the keycodes of the keys being pressed (perhaps in the status bar?) - that would make it a lot easier to fix/create keymaps
  • Add preview of the RAM init pattern (2017-11-08)
  • Add 'revert changes' to dialogs/widgets to revert resources to their state when the widget/dialog was activated. (This is different from restoring to factory defaults) (2017-11-16)
  • Add a 'smart' cartridge attach dialog: show "preview" of .crt image if selected in the dialog, show only valid cartridge types when selecting a cart image.
  • Add a 'detach all drive images' item
  • Make Hotkeys user-defineable
  • make an option to force display size to 1x/2x/3x/4x
  • SID-Model setting is missing
  • Implement a playlist for VSID
  • Add HVSC song length database (SLDB) support to VSID
Song lengths are retrieved for SID files, but actually implementing proper "skipping to the next tune" requires some research. The weird way VSID links against other libs and especially the Gtk3 widgets doesn't really help.
  • Add HVSC sid tune information list (STIL) support to VSID
Implemented, but the presentation is absolutely horrible, requires delving into the GtkTextBuffer API to provide proper indentation, font style, maybe (subtle) colors, etc.
  • Add HVSC BUGlist support to VSID
Support for this is available in src/hvsc, but there are very few actual entries in the BUGList.txt file. Maybe skip this one?

Documentation Wall of Shame)

The Gtk3 UI code is documented using Doxygen (as is the rest of VICE *cough*), but there are quite a few files not documented properly, so here's a little list of files needing updating (I've made doxygen skip novte/, that code is too weird, and I'll skip imported stuff like linenoise): (all files are in src/arch/gtk3, unless mentioned otherwise)

  • rs232-win32-dev.c
  • archdep.h
  • archdep_unix.c
  • archdep_unix.h
  • archdep_win32.c
  • archdep_win32.h
  • blockdev.c
  • coproc.h
  • dynlib-unix.c
  • fullscreen.c
  • joy-osx.h
  • joy-unix.h
  • joy-win32.h
  • kbd.c
  • kbd.h

And many more to come



  • ALT-D (toggle fullscreen) sends a D to the emulator
  • FFmpeg media recording behaves unexpected when entering the menu [4]
  • x64 uses the japanese kernal font when japanese model is selected
  • switching to VDC in x128 crashes on some setups [5]
  • in x128 hammering runstop/restore would crash the emulator in sdl_canvas_create, the SDL2 version of this code is broken [6]
  • use different icons for the various emulators/executables
    • embed icons into windows .exe files
  • make whole screen black when entering ui
  • when adjusting video/crt params, update the colors in realtime and show some color testpattern
  • some menu items need status text to show that the action has been done.
    • Drive>Fliplist settings>Add current image to fliplist
    • Drive>Fliplist settings>Remove current image from fliplist
    • Drive>Fliplist settings>Attach next image in fliplist
    • Drive>Fliplist settings>Attach previous image in fliplist
  • at a lot of places "inactive" (as in "cant be selected") menu items are missing the "N/A" on the right
    • Cartridge>MMC64>Enable MMC64 can not be used unless a MMC64 ROM has been selected, it should be made inactive if not you can enable it without an image, and then flash the bios inside the emulation
  • "pause" does not the green "tick" indicator when enabled
    • "advance frame" should be disabled when not in pause mode
    • entering the menu unpauses the emulation, this is required to trigger canvas refresh. unfortunately, due to how the UI is written, this can not be easily changed
      • also re-enabling pause mode when leaving the menu doesnt work with the current code


  • add pageup/down home/end keys for menu navigation
  • A better way of showing filenames (maybe using contraction) needs to be made
File Selector
  • hide "dot files" in the file selectors (on *nix) [7]
  • add filtering in file requester
  • there is no interface for browsing files inside (d64..) images
Virtual Keyboard
  • shift/cbm/ctrl should be "sticky" (right now shifted keys are entered using backspace/cancel - which is odd)
  • Implement a playlist for VSID
  • Add HVSC song length database (SLDB) support to VSID (both .txt and .md5 file format)
  • Add HVSC sid tune information list (STIL) support to VSID
  • Add HVSC BUGlist support to VSID


  • Sound starts to distort heavily after few minutes [8]
  • Sounds terrible unless sampling is lowered from default 44Khz to 22Khz [9]
  • Emulator in default config makes no sound unless the OutputMode is changed to Stereo. [10]

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)
    • building with `--enable-shared-ffmpeg` will fail when not root. VICE's configure triggers a build and install of liblame which tries to install into /usr/local/lib.
    • building out-of-tree currently fails with:
In file included from ../../../vice/src/lib/libffmpeg/libavutil/avutil.h:289:0,
                 from ../../../vice/src/lib/libffmpeg/libavutil/samplefmt.h:24,
                 from ../../../vice/src/lib/libffmpeg/libavcodec/avcodec.h:31,
                 from ../../../vice/src/lib/libffmpeg/libavformat/avformat.h:255,
                 from ../../../vice/src/gfxoutputdrv/ffmpeglib.h:36,
                 from ../../../vice/src/gfxoutputdrv/ffmpegdrv.c:37:
../../../vice/src/lib/libffmpeg/libavutil/common.h:50:10: fatal error: libavutil/avconfig.h: No such file or directory
 #include "libavutil/avconfig.h"
compilation terminated.
Makefile:507: recipe for target 'ffmpegdrv.o' failed

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 offsets (at least CIA/VIA already handled)
    • an insane amount of regression testing (preferably with new testprogs where needed)

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

  • sound sync needs a rewrite, its too complex and fails a lot

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. ([11])
    • c64/c128 SCSI expansion support. ([12])
  • Cartridges
    • IDE64 improvements
      • IDE64 eth64 shortbus expansion support. ([13])
      • IDE64 duart shortbus expansion support. ([14])
    • Clockport improvements
      • Silversurfer (UART) support ([15])
      • IDE64 based eth64-II support ([16])
    • Community Information Locator Commodore 64/128 addon cartridge ([17])
    • RAM Floppy (REX 9680) support
    • Daisy Sound sampler audio input support. ([18])
    • PS64 speech cartridge support. ([19])
    • Voice Messenger speech cartridge support. ([20])
    • ramlink support. ([21] [22])
    • ramdrive support. ([23])
    • turbo master cartridge support (4Mhz 65C02). ([24] [25])
    • turbo process cartridge support (4Mhz 658156). ([26] [27])
    • flash-8 cartridge support (8Mhz 65816). ([28])
    • SCPU cartridge support (20Mhz 65816). (in progress, has lead to a new emulator called xscpu64) ([29] [30]) (
    • The Final Chesscard (65c02) ([31])
    • German Btx cartridge (6803)
    • 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. ([32])
    • BI-80 cartridge support. ([33])
    • Buscard II IEEE488/printer-port cartridge support. ([34])
    • "Disk Mate" (Datel)
    • MAYA Software Eprom Cart
    • PCC-4/PCC-8 Eprom Cart (Jason Ranheim)
    • "Alien Flash"
      • VICEminus had this
    • Software of Sweden Megacart
    • DUBCRT
    • "MegaOne" - Easyflash compatible Flash cartridge, see here
  • Cartridges that wont be emulated:
    • SoftPROM cartridge ([35])
      • 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. ([36])
      • 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
    • "GeoAction"
      • pointless, equivalent to Action Replay + GeoRAM/RamCart
    • "Flash Gordon"
      • pointless, external kernal with flash, prototype (not released)
  • Userport
    • CBM1660 (userport) modem300 support. ([37])
    • CBM1670 (userport) modem1200 support. ([38])
    • FB-RS232 (userport) support. ([39])
    • c64 p64 midi interface: ([40])
    • Scanntronik handyscanner (userport) support. ([41])
    • Video Byte II video digitizer (userport) support. ([42]) ([43])
    • Computera Eyes video digitizer (userport) support. ([44] [45])
    • Userport RocketDrive support. ([46])
    • CIA-IDE-HD support. ([47])
    • Aprotek universal rs232 adapter support. ([48])
    • Comet64 support. ([49])
    • L. Pantarottos adapter support. ([50])
  • Tape Port
  • Video output.
    • c64 LCD64 screen support. ([56])


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



  • add support for "speedy" freezer cartridge


  • PET ROM-socket RTC support. ([60])
  • 8296 pet hardware ram lines connected to userport support.
  • 8296 RAMdisk 2008 support. ([61])
  • 8296 pet switchable 4 screens output support.
  • pet IEEE488 -> IDE/RS232 support. ([62])
  • High-Res
    • High-Res Technologies Graphics Board support. ([63], [64])
    • Data Becker CBM-8000 hi-res graphics support. ([65])
    • SuperSoft High Resolution Graphics Board support. ([66])
    • Eltec petGRAFIK support. ([67])
    • Delph Electronics 8000C support. ([68])
  • MTU K-1002-2 DAC sound system support. ([69])


  • cbm2 z80, better nec v20, support.
  • cbm2 8088 support. ([70])
  • B700 HiRes Graphics Board support. ([71])