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SID Factory II

SID Factory II is a cross-platform editor for composing music that will work on a Commodore 64. It uses the reSID emulator and is currently in open BETA. You can download binary release builds from here. To build from source, have a look here.

Main programming by Thomas Egeskov Petersen, with assistance by Jens-Christian Huus and Michel de Bree.

Notable features:

  • Uses the renowned reSID emulator
  • Tracker-like interface, using JCH's contiguous sequence stacking system and Protracker note input layout.
  • Choice of various music drivers made by pioneer musicians Laxity and JCH , optimized for use in demos and games on the Commodore 64.
  • A hotkey opens a surrounding overlay with help for both editor and driver.
  • Imports Goattracker, CheeseCutter and MOD files.
  • Supports both SID models 6581 and 8580 for PAL and NTSC.
  • Unlimited undo
  • Multiple songs
  • Copy / paste and modify selected area
  • Built-in packer and relocator to position the music anywhere in the Commodore 64 memory. Relocate used zero page adresses.
  • Includes demo tunes to learn from.
  • Cross platform: Windows, macOS (Intel and ARM) and Linux versions.
  • Configurable settings, shortcuts and keyboard layout
  • Open source

SID Factory II screenshot


Last commit Build windows binaries Build macOS binaries Build linux binaries

Please report issues in our issue tracker.

Next release

Commits since last release

  • Changed: Configuration parameter Window.Scale now has a range from 1.0 to 10.0, so users can blow up the screen even bigger. Values below 1.0 were not working correctly.

Build 20221007

  • Fixed: #162 Crash when converting NP20 and GT tunes.
  • Fixed: Crash when using a loop point beyond position 128
  • Fixed: #161 A bug where sometimes you couldn't edit sequences before hitting the play button.

Build 20220914

  • Added: #37 Multi song support. Allows you to edit multiple order lists that share the same sequences and sounds. Press F7 to check it out.
  • Added: Marking and copy/paste functionality in the song list
  • Added: Marking and copy/paste inside sequences (even across boundaries)
  • Added: #74 Configurable virtual piano keyboard layout. (Thanks to Wolfgang Kreutz for requesting)
  • Added: #119 A song can be made to stop playing instead of looping.
  • Added: An option to set the emulation sample rate to a user defined value (Thanks to Tammo Hinrichs for implementing)
  • Added: More than 30+ new source tunes by JCH and Vincenzo
  • Fixed: Scrolling in the song list using the mouse wheel
  • Fixed: reSID won't output a click anymore when launching SID Factory II or loading/saving files (Thanks to Tammo Hinrichs for implementing)

Build 20211230

  • Added: You can now add labels for song list rows. Left-click to edit a label.
  • Added: Note delay; delay a note by 0-F ticks. This is a feature of the new default driver 11.04
  • Added: An option in the packer to specify the base for zero page addresses that the player uses.
  • Added: Documentation on how to customize configuration using a user.ini file. Including a default template in /documentation/user.default.ini.
  • Added: Configuration options:
    • Window.Scaling to scale the contents of the window. (Thanks to Matty Seito for suggesting)
    • Editor.Driver.Default to set the default driver that is loaded when starting up the editor.
    • Editor.Confirm.QuickSave to enable/disable confirmation dialog on quick save.
    • Sound.Output.Gain for boosting/lowering output volume of the editor.
    • Disk.UserFolders and Disk.UserFolders.Aliases to add your favorite folder shortcuts to the file browser.
    • Disk.Startup.Folder to set the default startup folder for the file browser.
    • Editor.Follow.Play to set default follow play on/off.
    • Editor.Sequence.Highlights to set default sequence highlights on/off.
    • Sound.Emulation.8580.FilterCurve for adjusting the filter of the 8580 model.
    • Sound.Emulation.6581.FilterCurve for adjusting the filter of the 6581 model.
    • Sound.Emulation.Default.Model to set the default SID model (6581/8580) on startup.
    • Sound.Emulation.Default.Region to set default region (PAL/NTSC) on startup.
  • Changed: #142 the list of keycodes that can be used for remapping is complete now. Please note: the names for keycodes starting with num are renamed to start with kp_.
  • Changed: macOs #146 the official macOS distribution is now a universal application, meaning it will run native both on the new M1 (arm64) and the Intel (x86_64) architecture. The architecture the application is running on is reflected in the build number in the lower right corner of the startup screen.
  • Fixed: More accurate clockspeed (Thanks to Lazlo Vincenzo Vincze for reporting)
  • Fixed: macOs #131 SF2 won't compile on mac with Silicon M1 CPU. (Thanks to Rolf Greven for reporting and suggesting the fix)
  • Fixed: linux #133 Emulation error when starting up linux version. (Thanks to Maurizio Dall'Acqua for reporting)
  • Fixed: linux #134 SF2 won't compile on Arch Linux (Thanks to jansalleine for reporting and suggesting the fix)
  • Fixed: #137 Instability in filter table when jumping to set command in default driver.

Build 20210104


  • Added: The converter has now been embedded into the editor; just load MOD, SNG or CT directly
  • Added: Converting from MOD will show a dialog for choosing which of the four channels to ignore
  • Added: Ctrl-Shift-F for inserting the first empty unused sequence
  • Added: Ctrl-D for duplicating and replacing the currently edited sequence
  • Added: Ctrl-Shift-D for duplicating and appending sequence after the currently edited sequence
  • Changed: Splitting a sequence with Ctrl-B now splits to the first empty unused sequence
  • Changed: macOS Copy/Paste/Undo/Redo are now under the standard macOS key combinations (Cmd-C, Cmd-V, Cmd-Z, Shift-Cmd-Z) (Thanks to Bastiaan Winde for reporting)
  • Fixed: #91 cannot edit tracks anymore after dialog has been shown. (Thanks to Arjen Bokhoven for reporting)
  • Fixed: macOS #71 switch instrument/command while in a table (Thanks to Adam Davidovics for reporting)
  • Fixed: macOS #67 crash when run from a path with spaces (Thanks to Arjen Bokhoven for reporting)


  • Driver update 11.03 adds a filter enable flag bit in the instruments


  • The standalone converter has been removed due to the converter nowing being embedded into the editor

Build 20200911


  • The overlay can now be shown inside the editor with F12 and also changes depending on what driver is loaded
  • Added Ctrl+L for setting a song loop position (the order list words will turn green in that spot)
  • It is now possible to delete a file in all file dialogues by hitting the appropriate key
  • Seven new color schemes have been created in addition to the default one
  • The importer now also carries over auxiliary data (e.g. table descriptions)
  • Upgraded the ReSID emulation (resid-fp) to the latest version
  • Fixed .. erroneously interpreted as a file to be opened instead of browsing back
  • Fixed tracks not unmuted properly after muting them and then loading a different .sf2 file
  • Fixed the editor crashing when trying to optimize a song with no sequence data
  • Fixed not being able to properly play from a bookmark when showing tracks of uneven lengths
  • macOS Now using Minus and Shift+Minus for fast/faster forward
  • macOS Instrument up/down is now Cmd+Up/Down while Command up/down is now Shift+Cmd+Up/Down
  • macOS You can now open .sf2 files with SID Factory II directly from Finder (Open With)
  • macOS Backward compatible until macOS 10.9 (Mavericks)


  • Driver update 11.02 adds commands for pulse program index, tempo change, and main volume


  • Added a third conversion option for handling .ct source tunes from CheeseCutter
  • The SNG and CT converters now support the pulse index and main volume commands in driver 11.02
  • The MOD, SNG and CT converters now support then tempo change command added in driver 11.02
  • Command description labels are now created by the MOD and SNG converters too


  • Expanded the user manual with a table of contents, chapters about the data tables, and various pictures
  • The notes.txt file has been overhauled to show a complete list of all default keys for both Windows and macOS
  • The text files for all of the drivers have been polished to be easier to read at a glance


  • The PowerShell script for the bright overlay is now deprecated and will no longer be included
  • The area previously known as the gray order list is now called the song list instead

Build 20200718

  • Added a dialog box message for when saving fails
  • Added a dialog box message for when selecting a folder fails
  • macOS Fixed crash bug when trying to open a folder you had declined from a system dialog
  • macOS Editor ran without SDL2 being installed; added latest version of SDL2 to the package
  • Fixed crashing when trying to display unknown characters (usually in the file menu)
  • Fixed note preview using Caps Lock not working
  • Fixed note preview sometimes behaving inconsistently
  • Fixed left/right "blindness" in user manual

Build 20200716

  • Added description labels in the command and instrument tables
  • All drivers have been updated with meta data for the new descriptions capability
  • Also updated all the demo songs with command and instrument descriptions
  • Updated the converter to copy instrument descriptions from GT2 and MOD files
  • Changed hotkey for bit editing in tables to Shift+Enter because of descriptions now using the Enter key
  • Improved the table layout handling to allow for vertically tiled tables
  • All tables can now be accessed with an Alt+[letter] hotkey (the letter is highlighted in the table name)
  • A separate macOS build has been released for the first time (maintained by Michel de Bree)
  • Added the Ctrl+U hotkey for toggling between lower and upper case letters for all hexadecimal values
  • You can now drag-and-drop an .sf2 source file directly into the editor
  • Added an exit application confirmation dialog
  • All file lists now include a .. line for browsing back to the parent folder
  • Upgraded the ReSID emulation (resid-fp)
  • Changed the application caption text (filename now comes first)
  • Debug functionality added for examining ReSID output
  • Fixed a threading issue that could cause instability in the ReSID emulation
  • Fixed inserting/deleting rows in sequences not immediately being reflected in the order list overview

Build 20200610

  • Updated fast forward: ½ = 4x update, Shift+½ = super fast update
  • Added Ctrl+I during sequence editing for inserting the current selected instrument value. If a value is already set, it will be cleared
  • Added Ctrl+O during sequence editing for inserting the current selected command value. If a value is already set, it will be cleared
  • Added Ctrl+Space during table editing (if keyplay mode is on) - will play like Space alone but apply the current highlighted command, regardless of which table is in focus
  • In the marker view, Enter (or left-click) will move the current track position to that of the marker. Ctrl+Enter (or double-click) will do the same and then start playback
  • Reversed the direction of the CPU usage graph
  • Added command-line parsing, so that it is possible to associate .sf2 files with the editor and open them in File Explorer
  • Added NumPad+Plus and NumPad+Minus for incrementing and decrementing the currently selected index of the instrument table
  • Added Ctrl+NumPad+Plus and Ctrl+NumPad+Minus for incrementing and decrementing the currently selected index of the command table

Build 20200603


  • Fixed the meta data for command action keys (jump to relevant tables on Ctrl+Enter) in all variants of driver 11


  • Fixed import strings to say import music data and dialog box to reflect the same too
  • Fixed importer assertion when trying to import an empty project (i.e. a driver)
  • Fixed Ctrl+V (paste) not notifying the order list overview
  • Editing octave down/up has been moved to F3 and F4, transpose current sequence one semi-tone down/up has been moved to Shift+F3 and Shift+F4, and transpose current sequence one octave down/up has been moved to Ctrl+F3 and Ctrl+F4
  • Added fast forward on the ½ key
  • Fixed a bug in directory enumeration that would cause a crash when trying to access some system files

Build 20200528


  • Added automatic update of build data which is printed in right bottom of the splash screen
  • Added PNG support and a temporary embedded logo
  • Pressing End in a table will set the row of the last occurrence of a zero-only row found from the bottom and upwards
  • OrderlistOverview: Added Ctrl+Enter to move to and start playing from position
  • OrderlistOverview: Mouse left-click will select and move tracks view to position
  • OrderlistOverview: Mouse double-click will select and move tracks view to position and start playing from position
  • OrderlistOverview: Implemented Page Up and Page Down (skips 20 lines)
  • OrderlistOverview: Added Home which goes to top visible then first index, and End which goes to last visible then last index
  • Tracks and order list focus: Fixed issue where cursor position would be misaligned when focusing on order list entry and pressing Ctrl+G
  • Changed Shift+F2 to play from the event position of the top current sequence of the track in focus (or last in focus)
  • Added Space during table edit for previewing the last note played with Shift+[note] value (this will do nothing if not already in "play through input" mode)

Changes to earlier versions are not available.


SID Factory II is a cross-platform editor for composing music that will work on a Commodore 64. It uses the reSID emulator and is currently in open BETA.






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