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Hoxs64 is a Commodore 64 emulator for Microsoft Windows. It features Cycle-based (CPU, CIA, VIC, SID) accuracy, 1541 disk drive, tape deck, full screen mode, configurable keyboard or joystick, file support (D64 G64 P64 FDI TAP PRG P00 T64) and much more!


Windows: XP+

GPU: DirectX 11.1+ components (32-bit / 64-bit) required  

Most Recent Changes


  • Fix C64 load a saved state regression bug affecting cartridges.


  • ImGUI remember directory path after closing the application. 

  • New option to slow-load a host PC .PRG file via a more realistic 1541 disk load, instead of using instant memory injection. This is possible by both the user interface and command line options.

  • REU option for 16 megabytes of RAM. Ability to load .REU files.

  • Put back full screen pixel doubler option "1x" to turn off image stretch-to-fit.

  • Retro Replay cart bug fix stuck register DE01 bit 7: bank-address bit 15 for ROM banking.


  • Added missing keyboard assignment dialog key boxes for COMMA and DOT.

  • Improve unconnected IO emulation in the disk drive memory map.


  • Regression fix to save joystick settings the to registry; put back missing key values "Joy1GUID" and "Joy2GUID".


  • New menu options to save and load settings from an INI config file.

  • New command line option -configfile
    Loads settings from an INI config file specified by which can either be a full path or
    a path relative to the application folder. Double dot ".." and single dot "." path elements are not
    supported. If the -configfile option is missing it will look for a file hoxs64.ini within the
    application folder. If the hoxs64.ini file is missing it will load settings from the registry.

  • Keyboard key map assignments must now be explicitly specified else the C64 key will be unbound. Previous versions would assume default key assignments. Please check your key assignments are not blanked after running this version. Please remap your keys as required.

  • The ImGui menu is now always hidden if the mouse is in the lower half of the screen.


  • Fix keyboard settings dialog that was broken in v1.1.1.0.


  • Put back accidentally deleted SID player driver.

  • Fix corruption bug with the REU swap command. This fixes Sonic the Hedgehog by Mr. Sid.

  • Fix the joystick loading of settings to support a blank axis selection.

  • Set D64 sector gap to 7 bytes.

  • Drive motor linear spin up time added.

  • Drive VIA1 Port A improved simulation of floating pins.


  • Fix memory leak when loading a save state file.


  • Save state file fix.


  • Added Commodore 1750 REU 512K RAM expansion cartridge. REU option added to the auto load dialog. Added new command line -reu512k.

  • Keyboard assignment dialog fixes. Enable the delete key to clear key assignments.

  • Drive VIA fixes for VICE tests testprogs\drive\viavarious\via20.prg | via21.prg

  • Testbench mode fix to save the most recent frame PNG.

  • New debugger command to trace a number of system clocks.


  • issue #4: cartridge system 3 fix plus other related cartridge register address comparison fixes.

  •  Corrected DirectX pixel sampler mode from D3D11_TEXTURE_ADDRESS_WRAP to use D3D11_TEXTURE_ADDRESS_CLAMP to fix graphical artifacts seen at the  boundaries of the display area.


  • Prevent ImGUI from saving imgui.ini text files everywhere.


  • Fix broken command line relative path handling.

  • Improved performance of quickspeed from the 100Hz mode.

  • Remove possibly uncommon VIC bug such that a sprite with x-position 0x163 gets drawn at 0x164. Some but not all real C64s have this bug.

  • Use the new DirectX flip model if using Windows 10.


  • Fix null pointer access start up crash on Windows 7.

  • Automatically position the ImgUI popup when out of bounds.

  • Automatic mini-dump file creation with the application folder for application crashes.


  • Fix missing XInput1_4.dll error on Windows 7.


  • New DirectX 11.1 graphics implementation to replace the old DirectX 9
    implementation. Requires Microsoft Visual C++ 2019 runtime installation.

  • Fix CPU DMA timing bug with SHA SHX SHY.

  • CIA shift register timing fixes to accommodate Vice testprogs:

  • New ImgGui based file selector for full screen mode with option to opt
    out of windowed mode use.

Show Previous Changes

02 November 2019 v1.0.25.0
1) Added 100Hz full screen frame rate doubler option to help prevent IPS LCD
pixel burn in when using G-Sync.

22 October 2019 v1.0.24.0
1) Improved G-Sync performance with the host CPU aggressive mode.

12 October 2019 v1.0.23.2
1) Fix joystick settings dialog configuration fault.

03 October 2019 v1.0.23.1
1) Added aspect ratio resizing option to windowed mode.

2) Added 6th key to the joystick assignment key map.

3) Fix configuration save / load of joystick fire 2.

25 September 2019 v1.0.23.0
1) Allow PC joystick to control up to 5 C64 keys.

2) Monitor refresh option added to emulation video settings.

25 August 2019 v1.0.22.4
1) Fix to remember the address of a disused extra SID chip.

25 August 2019 v1.0.22.3
1) 8 SID load from a saved state file fix.

25 August 2019 v1.0.22.2
1) 8 SID configuration to support the "The Tuneful Eight [ultimate]"

24 August 2019 v1.0.22.1
1) SID file loading adjustment.

24 August 2019 v1.0.22.0
1) Multiple SID chip configuration added to the "chip" tab settings. Up to 4
SID chips can be configured. Added SID stereo / mono toggle option.

2) Stability fixes and improvements to the built in sid file player to
support version 4 sid files with automatic multiple SID chip configuration.

12 August 2019 v1.0.21.2
1) Changed command line option -autoload "hostfilename.d64" ":c64filename"
such that c64filename will have the case flipped.

2) Added command line option "@" to index a directory with no file type filter.

02 June 2019 v1.0.21.1
1) The debugger now displays and parses all numbers using the current selected radix (hex or dec)
while permitting the use of "$" and "." as radix overrides.

2) Fixed broken loading of a cartridge with in a save state file.

3) Bug fix for randomly distributing keyboard and joystick input into the video frame.

4) Changed ANE to use 0xEF as the magic constant as recommended by Groepaz.

27 April 2019 v1.0.21.0
Fix ANE opcode for Turrican 3

27 April 2019 v1.0.20.0
1) Added debugger step over JSR and step out with stack instructions functionality.

2) Fixed incorrect memory map while using the debugger that allowed the VIC to read from IO space.
This caused Emufuxx0r to fail while using the debugger.

24 March 2019 v1.0.19.0
Fix track wrap around disk image corruption to the file produced with "Save as D64".

12 February 2019 v1.0.18.0
1) Fix 1541 drive memory map that was broken since v1.0.14.0. The title Intoxication by Singular is now working again.

09 February 2019 v1.0.17.0
1) VIC emulation improvement to accurately emulate the early C-Data usage whenever X-Scroll is
decreased by 4 or more.

25 December 2018 v1.0.16.0
1) Prevent memory buffer overflow error when mounting G64 disk files that
contain tracks that are longer than 7928 bytes. Allow arbitrary length G64
track data to be scaled to the emulated disk.

24 December 2018 v1.0.15.0
1) Fixed G64 file header track size sanity check.

22 December 2018 v1.0.14.0
1) Added VIA6522 shift register emulation to support raw captured VMAX4 loaders.

2) CIA Time Of Day emulation accuracy improvement.

02 December 2018 v1.0.12.0
1) Allow game device axes to be unselected in the joystick settings.

2) Experimental support for game devices with more than 32 buttons and up to 128 buttons.

3) Fix to broken save state.

18 November 2018 v1.0.11.0
1) SID envelope timing fixes. SID sustain register cycle accurate response to changes. Update to
the SID noise write back behaviour.

04 November 2018 v1.0.10.0
1) SID envelope timing fixes to accommodate VICE test programs in
Also improved is the timing of gate attack during release and gate release during attack as
measured by own test programs.

15 April 2018 v1.0.9.9
1) New joystick configuration and fixes. Multiple host game device buttons
can be assigned to a C64 joystick function.

04 February 2018 v1.0.9.8
1) Fixed audio clock sync sound bug that can happen when running a monitor
FPS that is less than the emulated FPS.

28 January 2018 v1.0.9.7
1) CIA ICR interrupt regression fix that was broken in v1.0.9.6 that prevented the game
International Karate from working.

2) Fixed audio clock sync that was causing slow downs in windowed mode VBL sync.

01 January 2018 v1.0.9.6
1) CIA old timer B bug timing fixes for Wilfred Bos's alternate version of the dd0dtest.

2) Updated 8580 SID combined wave with slightly improved samples from a real C64C CSG 8580R5.

3) Added a new joystick setting to enable the use all fire buttons.

4) Added separate VBL sync or line sync options for both Direct X full screen and windowed mode.

5) Fixed the "Stretch with border clip" in some resolutions to provide a more optimal zoom.

20 September 2017 v1.0.9.5
1) Fix for saving and loading user preferences that was broken in v1.0.9.4.

17 September 2017 v1.0.9.4
1) CIA serial and CNT timing improvements thanks to test programs written by

2) Added VIC-II colour palette user configuration dialog box.

3) Added command line options (see hoxs64.txt) to support the VICE 64

4) Changed the colour RAM reset pattern to use bytes $0C and $03 as per the
same C64C whose RAM reset pattern is already used.

19 March 2017 v1.0.9.2
1) Fixed memory leak when changing the floppy disk image.

2) The joystick game controler will now respond to all POV/hat switches.

21 February 2017 v1.0.9.1
1) Fixed CPU opcodes SHS SHA SHY SHX ARR (decimal mode) to pass the VICE tests.

2) Added SID noise write back behaviour.

3) Corrected the SID master volume position to be after the SID filters. Was broken since v1.0.8.8.

5) SID ring modulation fix.

6) Corrected sector gaps when reading a D64.

7) Adjusted 1541 drive motor spin down timing as required for Wonderland XIII by Censor Design.

8) Fixed fault with save state / load state.

9) Fixed fault with FDI save.

10) Fixed Ultimax open address fetch.

2 January 2017 v1.0.9.0
1) Added Benjamin 'BeRo' Rosseaux's P64 1541 file format. Hoxs64 incorporates the P64 source code
written by Benjamin 'BeRo' Rosseaux author of Mirco64
The P64 disk representation with its linked list management is now used as the internal real time
representation of the disk.

2) Fixed numerous bugs with the CIA Time Of Day clocks so as to pass the VICE test programs under

3) Improved CIA emulation to handle instructions that perform multiple accesses to address $DD0D
so as to pass the VICE test testprogs\CIA\dd0dtest\dd0dtest.prg

9 May 2016 v1.0.8.9
1) Fix VIC where a write to the raster compare register was causing a raster IRQ to occur one clock too soon.
This fixes "Vandalism News #64" reported by iAN CooG/HokutoForce.

10 May 2015 v1.0.8.8
1) Disk drive VIA fixes to pass the VICE testprogs\drive\viavarious test programs.

2) Sound improvement fix for last part of Comaland 2014.

3) Windows GUI fixes.

8 May 2014 v1.0.8.7
1) Resizable main window for windowed mode.

2) Fix Ultimax VIC fetch.

22 September 2013 v1.0.8.6
1) Fixed an EasyFlash cartridge fault when loading a 4KB banked CRT file or state file.

22 September 2013 v1.0.8.5
1) Added emulation state file save, load and restore facility.

2) Added Epyx Fastload cartridge.

3) Added screen border hide options.

4) Fixed Retro Reply cartridge banking fault.

5) Reworked the CPU code to accommodate XAA/ANE for a MOS8500 as reported by,_ANE)

6 January 2013 v1.0.8.4
Bug fix to opcodes AXH/SHY/AHX/TAS broken in v1.0.8.3.

4 January 2013 v1.0.8.3
Bug fix to VIC. Removed faulty VIC ClockNextWakeUpClock runtime (not debugger) mode optimiser code
that had caused the Technological Snow demo by Agony Design to fail since v1.0.6.3.

3 January 2013 v1.0.8.2
1) EasyFlash v2 title screen glitch now fixed by correcting the "hard reset" code to set the sprite
Y expansion flip-flops.

1 January 2013 v1.0.8.1
1) Added the EasyFlash 1MB cartridge. A simplified emulation of the AMD Am29F040 EPROM permits writing
and passes EasyProg v1.6.3 tests.

2) Fixed freeze and soft reset to spread randomly through the frame to improve the chance of a successful freeze.

30 December 2012 v1.0.8.0
1) New cartridge emulation with freeze function. Peter Schepers CRT format is supported.
The following cartridge emulations are supported.

Action Replay v[6 - 2]
Final Cartridge III (v3 only)
Retro Replay 64K RAM
Magic Desk
Ocean 1
Fun Play
Super Games
System 3
Simons Basic
Normal Cartridge

The CRT reader uses the in file reported chip bank numbers and not the order they appear in the file.

2) Fixed misreported raster position in the debugger when starting a new frame.

21 November 2012 v1.0.7.5
1) Added point and click raster position breakpoints. Breakpoints can be disabled with out being deleted.

2) Added command window with assemble, disassemble and C64 memory map selection.

3) Added disassemble window address finder.

4) Added disassemble window mouse wheel scrolling (WinXP+).

5) Randomisation of drive weak bits. Minor drive timing improvement.

11 March 2012 v1.0.7.4
1) The application is marked as "DPI Aware". All Windows GUI elements are DPI aware and will render
smooth clear text when used with Windows 7's "make text bigger" option. Only the windowed mode C64
bitmapped rendering remains non DPI aware as with previous versions.

2) Added a work in progress breakpoint listview with context menu options "Show Address" and "Delete
All Breakpoints"

3) Illegal opcode tweak for demo 'Errata' by Emulamer.

4) CRASHFIX: Fixed stack corruption crash when reading G64 files with custom speed zones.

5) CRASHFIX: Fixed application lock up bug while drag scrolling the disassembly window.

25 October 2011 v1.0.7.3
1) Enabled editing of the CPU registers and the disassembly mnemonics. The mnemonic edit box
accepts either 6502 assembly or space delimited numbers.

2) Fixed pixel glitch while stepping in the debugger.

3) Added up/left soft cursor keys.

4) Tweak for demo 'Bad Copy' by Emulamer.

17 April 2011 v1.0.7.2
1) Fixed broken 320x200 and 320x240 modes.

2) Added option for disabling DWM (Aero) for full screen mode.

13 April 2011 v1.0.7.1
1) Text rendering bug fix to disassembly window.

2) Added trace till IRQ/NMI function.

3) Potential missed breakpoint while tracing bug fix.

4) Miscellaneous monitor GUI fixes and improvements.

11 April 2011 v1.0.7.0
1) VIC sprite collision timing fixes.

2) VIC phase 2 fetch fix for Ruined Art demo.

3) Improved CPU disassembly monitor. Instruction based scrolling. Separate CPU windows
allow both clock step and instruction step with ablility to step through the IRQ and NMI cycles.
VIC raster line and cycle is displayed.

4) Fix to CIA Timer B bug.

5) ALT Q key nuisance fixed.

24 October 2010 v1.0.6.2
1) Fixes to the key matrix.

2) Fixed Time Of Day alarm fail to trigger bug that was introduced in v1.0.5.27 that
may cause the game Hypersports to get stuck on the clay shooting part.

3) Audio resample mode is now on when restoring default settings.

10 October 2010 v1.0.6.1
1) Adjusted all VIC $D011 and $D016 mode change transitions to give pixel exact output

2) Improved keyboard matrix emulation. Space bar now works correctly in the Nitro 16 demo.

3) Adjusted VIC light-pen timing.

4) Adjusted CIA6526A IRQ timing.

5) Common code base now supports both x86 and x64 compiles.
(x64 bit version is tested on Windows 7 with full DirectX install).

6) Added WinXP styles that use common control library 6.

7) Adjusted audio sync.

25 May 2010 v1.0.6.0
1) Added CIA6526 and CIA6526A options to the emulation setting dialog.

2) Corrected all valid VIC mode change transitions to give pixel exact output.

3) Adjusted IRQ DMA behaviour for instructions SEI and CLI.

4) Fixed a restore key bug.

5) Adjusted Quick Speed to honour the VBL Sync option.

6) Optimised the DirectX video device creation.

16 April 2010 v1.0.5.29
1) Corrected the sprite multicolour enable register transitions.

2) Corrected VIC mode change transition from text mode to multicolour text mode to give
pixel exact output.

3) Corrected VIC bottom border behaviour.

4) Fixed bug with the recently implemented edge triggered raster IRQ behaviour.

5) Bug fixes and performance improvements to the GCR to D64 converter that is used by the file dialog
directory browser, quickload and the save to D64.

6) Fixed bug with the quickload of D64 programs that should be started with SYS.

7) Added light pen IRQ re-trigger behaviour.

2 October 2009 v1.0.5.28
1) Bug fix to correct a 32 bit integer overflow bug that causes incorrect emulation behaviour after
1 hour and 13 minutes of continuous use.

13 August 2009 v1.0.5.27
1) Added general option to enable/disable opposing joystick directions.

2) Speed optimisation to the CPU, CIA and VIC. The emulation is noticeable faster
on lines with no DMA fetches and no IRQs

3) Bug fix to the reverse keyboard matrix. Was broken for years!

4) Accurate emulation of the $DD00 VIC bank switch bug.

Unless something is majorly broken, the next release will include the long awaited debugger. Work
on the debugger is now in progress.

12 July 2009 v1.0.5.26
1) Bug fix to the FDI file format reader. Rapidlok game Serve and Volley now works. Many other FDI
captures now work.

2) New "Disk on Separate Thread" option added to the general settings page. Multi-core CPUs will provide
increased performance when the serial bus is idle.

3) 1541 drive fixes.

4) Numerous VIC mid raster line mode change fixes. A newly discovered edge triggered raster IRQ behaviour
is now implemented as seen on both old and new VIC chips.

5) Joystick fixed to prevent opposing directions from being simultaneously pressed.

29 May 2008 v1.0.5.25
1) Bug fix for an un-initialised boolean that either allows head stepping while the motor
is off (the most likely case) or causes missed head steps depending of the "random" state of
the boolean.

29 May 2008 v1.0.5.24
1) Another adjustment to the 1541 drive head stepping logic and initialisation of disk drive
that is broken in the previous release as seen by excessive flashing of the 1541 LED.

2) The 1541 disk motor will run continue to spin for a short a fraction of a second after being
turned off. The disk loader for Star Trekking the Game is now more accurately accommodated.

28 May 2008 v1.0.5.23
1) Adjustment to the 1541 drive head stepping logic and initialisation of
drive internal track counter. Some quickloads including the Tsumami demo that are broken in
previous release are working again.

27 May 2008 v1.0.5.22
1) Adjustment to the 1541 drive head stepping logic to fix the demo Cafe Odd by Reflex that
was broken in the previous release.

26 May 2008 v1.0.5.21
1) The VIC fix for the Tsunami demo by Booze Design in v1.0.4.25 has proved to be an incorrect
model. The correct model that is now implemented allows sprite DMA to occur with the sprite not

2) The 1541 drive emulation has been corrected to prevent disk head movement in the same clock
as the disk motor is turned on.

24 May 2008 v1.0.5.20
1) VIC regression fixes and improvements to mid screen mode changes as seen on a C64C. The C64C
infamous grey dot bug is not emulated. The anomalous phase 2 VIC fetch that does not fetch $FF is
not emulated. Many more demos will correctly display stray pixels or not as per a C64C.

26 April 2008 v1.0.5.19
1) VIC fixes for bugs introduced in previous version. Some effects caused by a write to VIC $D016
mode control have been brought forward by 4 pixels.

2) The SID combined waves that use sawtooth will no longer respond to ring modulation as
observed on a C64C.

3) Fixed the disk inspector to discount empty directory records. Crest Avantgarde will now

20 April 2008 v1.0.5.18
1) Fixed NMI timing during BRK instruction.

2) VIC fixes including the adjustment of the Sprite Y Expansion and the charactor display
logic. The following demos are fixed. "Destruction" by Dream, "Spice Up Your Life" by
Triad and "Parados"

24 February 2008 v1.0.5.17
1) Added options to create and save either 35 or 40 tracks to a D64 file.

2) Added track align option for creating and loading D64 files.

3) Added command line options.
hoxs64.exe -quickload -alignd64tracks -autoload "c:\games\games.d64" 5
This will auto quick load program 6 from the file games.d64. Aligned tracks will be used.

4) VIC fixes. Numerous demos fixed.

5) 1541 disk VIA fixes.

27 January 2008 v1.0.5.16
1) VIC fixes. Stray black pixels removed from Scorpion demo.

20 January 2008 v1.0.5.15
1) Adjusted disk drive VIA timers. The Orbservan disk mag now loads.

14 January 2008 v1.0.5.14
1) Adjusted IRQ timing for branch instructions.

4 January 2008 v1.0.5.13
1) Fixed auto disk swap bug introduced in v1.0.5.11. Disk head does not remain high while
a disk swap is in progress.

2 January 2008 v1.0.5.12
1) Fixed overlapping IRQ and NMI timing. The Flexible demo part 3 flicker is fixed.

2) Fixed sound noise bug caused by an incorrectly truncated floating-point number.

1 January 2008 v1.0.5.11
1) Fixed memory bug in FDI disk decompression.

2) Fixed bug in RTI opcode. Flexible demo part 3 now works.

3) The disk head data line is held high when the motor is off. Startrek game now loads.

4) Fixed CIA PB6-7 bug introduced in v1.0.5.0

5) Reduced sound volumes to avoid wave cropping.

19 November 2007 v1.0.5.10
1) Fixed SounDemon’s sid emulation compatibility that was broken in the previous release.

2) Adjusted memory-reset pattern. An optional memory pattern file called c64.ram has been
added. The file was sampled and extrapolated from the memory-reset pattern of a C64C.
If the c64.ram file is missing then a default pattern is generated.

18 November 2007 v1.0.5.9
1) Fixed disk head movement while motor is off bug that was introduced in v1.0.5.0.
The LogosLand 2 demo works again.

2) The disk ROM is updated from 1541C to 1541-II. The game Kangarudy II works.

3) Adjusted SID oscillator register $D41B to read a one cycle delay as per an 8580 SID.

4) Adjusted memory reset pattern. The game Snow Queen and the demo Typical / Beyond The Force

5) Fixed assertion failure while performing a reset in debug mode.

6) Fixed long standing internal "first chance exception" whilst querying the application

28 October 2007 v1.0.5.8
1) Fixed memory write access general protection fault caused by using less than
full borders with sprites active around raster line zero.

21 October 2007 v1.0.5.7
1) The memory requirement of the Finite Impulse Response (FIR) filters is reduced without
compromising sound quality. There is increased performace of the 50.12Hz mode for machines
with relatively small L2 caches.

2) Added choice of two 50.12Hz modes. The large FIR mode performs best on large L2 caches
such as 4Mb. The multistage FIR mode performs best on smaller L2 caches.

18 October 2007 v1.0.5.6
1) Added C64 video speed option for 50Hz and 50.12Hz.

14 October 2007 v1.0.5.5
1) Improved screen saver disablement by responding to WM_SYSCOMMAND instead of changing
the system screen saver timeout.

13 October 2007 v1.0.5.4
1) Added border size options, "Full, "TV" and "Small".

2) Added show/hide floppy LEDs.

3) Improved handling of video mode changes.

10 October 2007 v1.0.5.2
1) Fixed slow performance with VBL sync by changing the presentation interval from

10 October 2007 v1.0.5.1
1) Fixed window resizing minor bug when going from fullscreen to windowed mode.

10 October 2007 v1.0.5.0
1) Upgraded to DirectX 9 October 2006 libraries or higher.

2) Added video mode and multi-monitor adapter selection.

3) Added full screen stretch-to-fit.

4) Added blit stretch filter selection.

5) VBL Sync works in both windowed and full screen.

6) Added floppy LEDs.

7) Temporarily disabled screen saver.

8) VIC fixes. TRC-TBI intro demo displays. Fixed the VIC LP IRQ response to the keyboard.

31 July 2007 v1.0.4.26
1) VIC timing fixes

30 July 2007 v1.0.4.25
1) VIC timing fixes. Stray pixels have been removed from the Tsunami Demo.

18 July 2007 v1.0.4.24
1) IRQ timing adjusted. VIA timers adjusted. SID and CPU register fade adjusted.
The following titles will now work:- "Locomotion", "Aurora 90%", "The Addams Family"
and "Star Expedition"

18 June 2007 v1.0.4.23
1) Bug fix to the TAP version 2 reader. The "Giana Sisters" tape file now plays.

2) Adjusted TOD clock to allow the possibility of a TOD Alarm IRQ occurring immediately on
a write to the TOD clock. The game "Hammer Fist" now plays.

7 June 2007 v1.0.4.22
1) Minor VIC fixes.

4 June 2007 v1.0.4.21
1) Fixed bug introduced in the previous version to the D64/G64/New disk insertion that
loads tracks into both the whole track and halftrack position.

2) 1541 ROM changed to a 1541C revision 2 to cure a half track miss-alignment issue that
prevents the correct saving to an inserted floppy following an attempted save with no
floppy inserted.

4 June 2007 v1.0.4.20
1) Numerous 1541 emulation fixes. The demo Intoxication by Singular and game Starflight
now work.

2) Fixes to the VIC border unit and background colours. The demos LCP_memories and Skaaneland
by Fairlight now display correctly.

27 May 2007 v1.0.4.19
1) Fixed assertion failure whilst using the monitor with a disabled 1541 disk drive.

24 May 2007 v1.0.4.18
1) Minor adjustment to the VIC under-border background colour logic. The "1993" part of
"Totally Stoned 2" by Booze Design is now pixel exact as seen on a real C64C.

21 May 2007 v1.0.4.17
1) Adjustment to the VIC sprite Y expand register. The game Flying Shark now displays

2) Adjustment to the CIA serial shift register to raise the initial byte complete IRQ after 15
timer  underflows instead of 16 timer underflows. The game Athena now displays correctly.

3) Adjustment to the VIC display enable bit. The game Elven Warrior now displays.

4) Adjustment to the SID ADSR. The HVSC sid tune /VARIOUS/G-L/Kordiaukis/Request.sid
missing instruments have been restored.

19 May 2007 v1.0.4.16
1) The VIC emulation as been enhanced to include a 4 pixel delay before responding to
changes to the sprite multicolor register. Stray pixels have been removed from the
"Krestage 3" Demo by Crest 50 pixel sprite upper border.

16 May 2007 v1.0.4.15
1) Fixed restore key freeze bug introduced in v1.0.4.12.

16 May 2007 v1.0.4.14
1) Added 25 pixel sprite feature used in the "Krestage 3" Demo by Crest. The demo will
now run unpatched.

2) Bug fix to broken sprite timing introduced in v1.0.4.12 that was noticed in the
"Royal Arte" Demo By Booze Design

15 May 2007 v1.0.4.13
1) Bug fix to Win9x file open/save dialogs introduced in v1.0.4.12.

14 May 2007 v1.0.4.12
1) Added disk image, T64 and SID file inspector to the Auto Load dialog box.

2) Added Quick Load to the Auto Load dialog box for fast loading PRG files from a CBM DOS
disk image.

3) Minor adjustment to the SID noise waveform. The California Games title music drums
now plays correctly.

4) Bug fix to the "Save As D64" option that guessed the wrong speed zone of a track which
resulted in a corrupted saved D64. The default speed zones are now assumed during a
"Save As D64".

5) ROMs are searched for in the following order. The folder of the executable. The current
system path.

12 October 2006 v1.0.4.11
1)  The CIA Time Of Day clock has been corrected to have the same quirky BCD count up
behaviour as the real thing.

2) The CIA Time Of Day count-up frequency has been corrected and now responds to
the 50Hz / 60Hz TOD input selector.

09 October 2006 v1.0.4.10
1) Fixed CIA Time Of Day freeze on write function. A freeze bug in the game
"Frankie Goes To Hollywood" has been fixed.

06 October 2006 v1.0.4.9
1) The Flexible Disk Image support has been upgraded to include the new FDI v2.1 format
with CRC-32 error detection.

2) T64 read-only file support has been added. A T64 directory browser has been added to
the Tape menu.

3) The SID resonance has been boosted.

4) The SID ADSR timings have been corrected to be cycle exact.

5) Fixed long standing incorrect implementation of the SID "Hard-Sync".

6) The SID "combined waveforms" now uses an 8bit wave table. The samples were taken from a
Commodore C64C with serial number "HB5 527013 E" via the SID register $D41B.

7) Minor adjustment of SID sample holding behaviour for waveform $00.

8) An intermittent performance slow down issue with the SID filters has been fixed. The
performance loss was a result excessive underflow with ultra small numbers known as
de-normal floating point numbers.

Many thanks to Stephan Parth for SID emulation testing.

22 August 2006 v1.0.4.8
1) The SID emulation has been improved. The amplitude modulators will hold the last
sample sent from waveform generators that have been set to output no waveforms.
Clicking, ticking and popping noises have been removed from the following sid tunes:
Sheep In Space
Sidewinder II
Brutal_Techno.sid by S. Bachliński (Moog) & Jetan

2) The combined waveforms have been adjusted.

3) Minor VIC-II fixes have been made. Several stray black pixels have been removed from
the bottom right of the "kiss" screen in +H2K demo by Plush. White flickering pixels
have been removed from the sprite multiplexer hidden screen in Krestage by Crest.

22 January 2006 v1.0.4.7
1) Sound bug fix to "resampling" mode.

22 January 2006 v1.0.4.6
1) Added SID "resampling" and "down sampling" options to the emulation settings page.
Previous versions implemented down sampling only. Resampling introduces less noise but
requires significantly more CPU power than down sampling. Resampling is off by default.

16 January 2006 v1.0.4.5
1) The length of time taken to reset the noise waveform via the "test bit" has been set
to 7 seconds. Version and lower never reset the noise waveform. Version
accommodated the SounDemons emulation detector test by introducing a reset delay that
took a tiny fraction of a second. As a result some noise bases sid files will play
correctly as they did in version

16 January 2006 v1.0.4.4
1) Version may suffer poor performance on a host CPU with L2 cache 256Kb or less.
The interpolation filter kernel size has now been slightly reduced to restore performance.

2) The sprite collision timing has been delayed by two pixels. As a result,
Emu-Fuxx0r V1 compatibility has been added in addition to existing Emu-Fuxx0r V2

15 January 2006 v1.0.4.3
1) Corrected delayed response of the SID wave feedback register $D418. Improved
combined SID wave forms emulation. SounDemons "Waveform Composer" emulation detection
test now passes.

2) Added Pete Rittwage's weak bit handling to the 1541 drive emulation as required by
some copy protected disk images.

13 January 2006 v1.0.4.2
1) Fixed bug that would silently fail to insert an FDI disk if the emulator write
protection was enabled prior to insertion.

11 January 2006 v1.0.4.1
1) Fixed GPF in Insert New Blank Disk.
2) Disk write protection bug fix.

11 January 2006 v1.0.4.0
1) Disk file support is expanded to include Vincent Joguin's FDI (Flexible Disk Image)
and G64 (Raw GCR Binary). G64 files can be loaded but not saved. FDI files can be both
loaded and saved. FDI support is limited to the Raw Pulse Stream Tracks format.

2) Non standard track layout D64 files are loaded more correctly but will save only as
FDI. Standard track layout D64 files will save as normal.

3) The 1541 emulation is enhanced to support bitwise resolution of disk tracks. Magnetic
disk pulses are specified to a resolution of 16Mhz. No more than one pulse can be
specified with in the same 1Mhz band arc of any track.  G64 files effectively specify a
bit resolution between 0.3Mhz and 0.25Mhz depending on the speed zone setting.

4) The 1541 floppy disk controller emulation includes all relevant internal counters
and shift registers.

5) 1541 VIA port latching and handshaking is now emulated.

6) Improved handling of disk protect sensor while swapping disks.

13 December 2005 v1.0.3.12
1) Fixed sprite bug introduced in release (v1.0.3.8) where a sprite could empty its buffer at
column cycle 63 even thought the sprite was hidden at X position >= 0x1f8. This was noticed as
occasional blank sprite lines in the second part of the "Ice Cream Castle" demo by Crest.

12 December 2005 v1.0.3.12
1) Sprite hiding, distortion and buffering near the fetch clocks is now correctly emulated.
"Demus Interruptus" by Crest should display now display correctly with true cycle based sprites.
2) Frame skip is off by default and VBL Sync is on by default.

20 November 2005 v1.0.3.11
1) Quick speed mode retains maximum compatibility by disabling sound output but not disabling the
SID emulation. The "Emu-fuxx0r v2" test will now pass in Quick speed mode.

14 November 2005 v1.0.3.10
1) Fixed instance corrupted sideborder graphics introduced in release (v1.0.3.8).
The problem was visible during a decreasing X Scroll in raster cycle 56.

12 November 2005 v1.0.3.9
1) Fixed some corrupted sideborder graphics introduced in the previous release (v1.0.3.8).

12 November 2005 v1.0.3.8 : Possibly the world’s first emulator to fool "Emu-fuxx0r v2".
1) Cycle based sprite emulation.
2) "Emu-fuxx0r v2" by Plush compatibility. The "Quick speed" toggle must be switched off to pass
the "Emu-fuxx0r v2" test. This is because the "Quick speed" toggle disables the SID emulation.
3) DExx memory compatibility.
4) SID digi boost option.

14 September 2005 v1.0.3.7
1) Corrected SID to return 255 for the X-Y game paddle positions. The game Lemmings will now work
in joystick mode.

12 September 2005 v1.0.3.6
1) CIA timers are set to 65535 following a hard reset. The game Netherworld will now run as a result.
2) Fixed CIA timer output to PB6 and PB7.

8 September 2005 v1.0.3.5
1) Improved SID player compatibility. RSID "C64 BASIC" mode support added. PSID 60hz CIA mode support added.

7 September 2005 v1.0.3.4
1) Bug fixes to SID player. RSID support. 60hz SID play mode is not supported in this release.

6 September 2005 v1.0.3.3
1) SID File version 1 and version 2 support.

6 September 2005 v1.0.3.2
1) Initial release of SID file player. Support is limited to the PSID "PAL Vertical Blank" variety.
SID files are loaded through the auto-load menu option.
2) Additional ring modulation bugs fixed.

20 August 2005 v1.0.3.1
1) Corrected poor sounding ring modulation noticed in Sidewinder II.

19 August 2005 v1.0.3.0
1) Fixed pulse width modulation to allow digi sound playback in Air Combat Emulator (A.C.E.)
2) Added F-key control boxes to the keyboard configuration page.
3) Added Quick speed toggle on Alt-Q.

15 August 2005 v1.0.2.9
1) Fixed digi sound playback that was noticed broken by Stuart Toomer.
2) Adjustment to filter to keep stable when operating above the pi/3 Chamberlin frequency limit.

13 August 2005 v1.0.2.8
1) SID filters implemented as a state variable Chamberlin filter.
2) SID ring modulation has been redesigned to use the method as described in the
"SID Primer" by Stephen L. Judd. The previous version used triangle
and sawthooth wave tables with wave multiplication.

7 June 2005 v1.0.2.7
1) Any PC joystick button can be selected as the fire button.
2) Improved CPU friendly mode.

8 December 2004 v1.0.2.6
1) Sound sampling set to 44100Hz

8 August 2004 v1.0.2.5
1) Bug fix to allow "Audio clock sync" to work with disabled disk drive emulation.
Previous versions require that drive emulation is enabled.

25 July 2004 v1.0.2.4
1) Bug fix in joystick configuration code. All joysticks should work now.
2) Pause function on Alt-P.

22 July 2004 v1.0.2.3
1) Joystick swap function on Alt-J fixed after initially released not working.

22 July 2004 v1.0.2.2
1) Audio clock sync option to prevent sound glitches on computers whose audio clock
is slightly in dissagreement with the windows "Performance Counter".
2) Joystick swap function on Alt-J
3) CPU Friendly option.
4) Minor fix to CIA ports to read pin levels instead of output levels.
5) domain name in service.

17 July 2004 v1.0.2.1
PC Joystick/Pad support available. Win2000 tested.

5 February 2004 v1.0.2.0
Direct Sound set to software mode. Some machines show much poorer performance
with hardware sound even with fast processors and memory. This is probably
because hardware sound is optimised for large sound buffers and Hoxs64 uses
small buffers. Try this version if sound is jerky with 600+Mhz PC.

29 March 2003 v1.0.1.2
1) Added Auto Load option to the file menu for easier C64 program loading.
2) Minor VIC-II fixes.

22 March 2003 v1.0.1.0
1) Added windows screen doubler with option to choose between a CPU
or a DirectX pixel doubler.
2) Changed C64 colours to RGB values provided by Stuart Toomer.
3) Changed full screen mode to prefer 8bit colour for performance.

10 March 2003 v1.0.0.10
1) Option to configure Keyboard assignments

2) Load/Save of setting to the registry. Setting are saved under

3) Minor VIC-II fixes. Hoxs64 can run all screens in the "Ice Cream Castle" demo
by Crest with out glitches.

1 August 2002 V1.0.0.4
Numerous improvements to the VIC emulation accuracy.

1) The sprite X positions are displayed more correctly when the X register is changed
on a line for which the sprite is active.

2) The border and boundground0 colours change 12 clocks after the write access
to the colour registers as explained in "Christian Bauer's VIC-II Article".
This rule applies regardless of the amount of XSCROLL.

3) If the value XSCROLL increases then the VIC will output idle state coloured pixels
only after the current character has been shifted out to the display.

4) Corrected the idle state colours underneath the border. "Demus Interruptus"
now shows all screen pixel perfect.

5) Sprites are corrupted if positioned near to the sprite data fetch clocks.
As a result, Hoxs64 will the run "Demus Interruptus" with out having to patch.

8 July 2002 V1.0.0.3
1) BUG Fix: Corrected colours that are fetched during the time that the VIC attempts to
read from memory whilst the CPU still controls the address lines.

17 June 2002 V1.0.0.2
1) BUG Fix: Intermittent loss of display during full screen mode operation.

7 June 2002 V1.0.0.1 (up to 30% faster emulation using frame skip)
1) New option on settings dialog to skip alternate frames (on by default). Use this
option if emulation speed is a priority.
2) Option to alter the synchronisation for full screen mode. "VBL Sync" (on by default)
is the slow but gives cleaner display switching. Line Sync is faster but may show small
visual glitches during animation.

7 June 2002 V1.0.0 (Better disk and sound)
1) The 1541 disk can be written to and can be saved to a D64 file on the host computer.
Changes to the current 1541 disk are not immediately saved to the host computer storage.
Changes to the current 1541 disk must be explicitly saved to the host PC through the Disk

2) Ability to insert a blank pre formatted disk.

3) Finally fixed the last of the sound glitches (arrgh!). If any one has sound
problems on 100% speed, then please let me know.

4) Synchronised screen redraw in full screen mode.

10 May 2002 V0.9D (Better disk and sound)
1) Improved disk drive emulation compatibility to allow more turbo loaders to work.
All loaders that are known to me at this time will now load.

2) Removed excessive function calls to the DirectSound "GetStatus" call. The result
is that the sound play back does not "jump" as much.

17 April 2002 V0.9C
1) Fixed a random chance of a "divide by zero" GPF when pausing and un-pausing the
emulation. This situation occurs when changing screen mode or accessing menus.

2) Fixed a bug with the CIA TOD clocks not counting up in correct order with respect
to "rollover and carry" from the LSBs to the MSBs.

3) Fixed disk drive emulation to cause a false SINC condition between changing
disks. Some software uses the false SINC as a means to detect when a disk has been

4) Fixed a bug that caused sprites in the patched demo "Demus Interruptus" not to
show correctly. This was because "Christian Bauer's VIC-II Article" did not mention
that the increment that is added to the internal register MCBASE (for sprite
pointer indexing) is dependant on the current value of MCBASE. After debugging the
demo "Demus Interruptus" I realised what happening and I was forced to rip this
table from VICE1.7

I would much love to know the logic in this table:-

const int vic_ii_sprites_crunch_table[64] =
1,   4,   3, /* 0 */
4,   1,   0, /* 3 */
-1,  0,   1, /* 6 */
4,   3,   4, /* 9 */
1,   8,   7, /* 12 */
8,   1,   4, /* 15 */
3,   4,   1, /* 18 */
0,  -1,   0, /* 21 */
1,   4,   3, /* 24 */
4,   1,  -8, /* 27 */
-9, -8,   1, /* 30 */
4,   3,   4, /* 33 */
1,   0,  -1, /* 36 */
0,   1,   4, /* 39 */
3,   4,   1, /* 42 */
8,   7,   8, /* 45 */
1,   4,   3, /* 48 */
4,   1,   0, /* 51 */
-1,  0,   1, /* 54 */
4,   3,   4, /* 57 */
1, -40, -41, /* 60 */

This is how the table would look in Hoxs64 V0.9B as per
"Christian Bauer's VIC-II Article" :-

const int vic_ii_sprites_crunch_table[64] =
1,   1,   1, /* 0 */
1,   1,   1, /* 3 */
1,   1,   1, /* 6 */
1,   1,   1, /* 9 */
1,   1,   1, /* 12 */
1,   1,   1, /* 15 */
1,   1,   1, /* 18 */
1,   1,   1, /* 21 */
1,   1,   1, /* 24 */
1,   1,   1, /* 27 */
1,   1,   1, /* 30 */
1,   1,   1, /* 33 */
1,   1,   1, /* 36 */
1,   1,   1, /* 39 */
1,   1,   1, /* 42 */
1,   1,   1, /* 45 */
1,   1,   1, /* 48 */
1,   1,   1, /* 51 */
1,   1,   1, /* 54 */
1,   1,   1, /* 57 */
1,   1,   1, /* 60 */

4 February 2002 V0.9B
1) Fixed a GPF memory read in the VIC code.

3 February 2002 V0.9A
1) Improved the DirectSound secondary buffer re-synchronisation. De-synchronisation
occurs as a result of the DirectSound play back clock rate being independent to the
clock that controls the emulation speed. All those random noise glitches should not
occur on machines that can maintain 100% emulation speed.

2) Fixed a CPU port bug that caused the status of cassette play button not be read
correctly until the port was written to. The two sided tape loaders should now work
as they did in version 0.7.

3) The disk track head position will be left unchanged between inserting disks.
The two disk game "Press Your Luck" will now load.

4) Fixed a minor VIC display bug that could occasionally cause multicolour text
to be incorrectly masked against a sprite.

5) Added a scrollbar to the debug window.

6) Added execute break point capability. An execute break point is toggled by
left clicking on the address label of a mnemonic.

7) Fixed the ARR undocumented opcode.

12 November 2001 V0.9
More of those fancy demos should now display.
FLI and IFLI should work. (It was sort of working before, if you wrote a program that
worked with the old Hoxs64 incompatible timing.)

1) Timing of interrupts with respect to the VIC --> CPU BA line has been fixed (I hope).
This information is not easy to find.

2) Introduced a 12 clock cycle delay between the "g-access" data fetch of the VIC and
the rendering of the pixels. Pixels are rendered with the colour register values that
are available at the clock that they are rendered, as opposed to the clock that the
pixels are fetched.

3) Fix to allow the border to be turned off by a switch from a 24 line to a 25 line
display while the raster line is any where on the "top comparison line". This
information seems to be missing from Christian Bauer's VIC Article.

4) Reworked CPU and VIC timing to allow the CPU to influence some additional
operations of the VIC at the same clock cycle as the write to the VIC registers.

5) Fixed the VIC to fetch the lower 4 bits of the current CPU opcode when accessing the
colour RAM while the address lines are in use by the CPU.

6) Introduced a 2 clock cycle delay (was 1 clock delay) between the CPU write to $D011
and the time that VIC goes from idle to display state given the various logic rules.

3 November 2001 V0.8D
1) Set disk drive speed from PAL Speed up to 1Mhz. Introduced a 1 clock cycle delay
for the disk drive to see changes to the serial bus. This has the effect of allowing
a wider variety of disk turbo loaders to now work.
2) "Limit speed" and "show speed" options in the settings menu.

30 October 2001 V0.8C
Fixed a sound bug that caused NT4 service pack3+ machines not to initialise the sound.
Fixed a minor bug with the CPU port.

26 October 2001 V0.8B
Fixed a sound bug that caused garbage noise if the sound emulation was turned off
and then a menu option was later selected.

26 October 2001 V0.8
1) Not NT tested yet. SID (Sound Interface Device) now works. The only the filters
are missing.

15 October 2001 V0.7D
1) Sprites can now be displayed in the extreme left and right edge underneath the

10 October 2001 V0.7C
1) Fixed incorrect background colour underneath the left right border.
2) Fixed a compiler optimisation error by disabling optimisations for the CIA
execute cycle. The game Bounty Bob now works again as it did in V0.7

10 October 2001 V0.7B
1) Left and right border can now be opened.
2) Fixed a display bug caused by a multicolour foreground pixel being cut in
half by the left border thus causing an incorrect colour. This was noticed in the
title screen of California Games as an odd coloured vertical bar near the left

9 October 2001 V0.7
1) New 1541 Disk drive emulation. The drive is read only and supports the D64
file format. Turbo and custom loaders should run except the so called "Blast"
game collection. This should not be a problem because "Blast" disks allow you
to manually load  games by their filenames.

2) Improved DirectX handling with full screen mode and enhanced support for
windowed mode.
The following windowed modes are now supported:
32 bit colour
24 bit colour
16 bit colour
8 bit palletised (256 colours)

The following full screen resolutions are now supported:

3) Fixed bug with 24 bit colour renderer.

4) DirectX 3 support for NT4 with service pack 3 or higher.

6 August 2001 V0.6b
Small speed optimisation of VIC-II.

29 July 2001 V0.6a
Fixed CIA2 ports to read highs when DDR set to input. Beamrider now works.

25 July 2001 V0.6
Initial release. The CPU, VIC, and MMU are fully functional. The CIA is
functional with no support for devices on the "user" nor the "serial" port.
There is no SID (Sound Interface Device). There is no disk support. The so
called DE00 programs are not fully supported but it must be remembered that few
real C64s can run DE00 programs.

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