Version 4.20 [December 29, 2023]:
[changes]
* Command Line: Switches are no longer allowed at the end of arguments, e.g. disk.atr/f or /f/nosi. Switches must now be separate arguments.
* Input: Removed the extraneous hidden Button 1 input on light pen/gun controllers.

[features added]
* Additions: Added PHLOAD.COM to trigger peripheral handler loads via type 4 polling.
* Cartridge: Added Williams 16K cartridge type.
* Cartridge: Changed existing JRC cart type to JRC6 64K without RAM and added JRC RAMBOX cartridge type.
* Cartridge: Added MDDOS cartridge type.
* Cartridge: Added COS 32K cartridge type.
* Cartridge: Added Pronto cartridge type.
* Cartridge: CAR types 76, 78-93, and 160 are now supported without advanced configuration overrides.
* Cassette: Load Data as Audio option now supports raw FSK and PWM data blocks in .cas files.
* Cassette: BASIC auto-boot can now handle BASIC program tapes that require RUN "C" instead of CLOAD.
* Command Line: Added /[no]casautobasicboot, /kernelref, /basicref, and /diskemu switches.
* Debugger: Symbols escaped with '#' prefix can now include @ in their name.
* Debugger: .vbxe_traceblits command now has a compact mode.
* Debugger: .vbxe_bl command now has a compact mode and can dump a blit list at an arbitrary address.
* Debugger: Added explicit option in the disassembly window for whether the current D register state affects symbol lookup for direct page addressing modes.
* Debugger: bta (set tracepoint on access) can now supply a default trace message.
* Debugger: Math pack symbols can now be unloaded independently.
* Debugger: Added static trace PBI (stp) command to auto-trace parallel bus interface firmware.
* Debugger: Memory window now accepts arbitrary address expressions.
* Debugger: Ctrl+F in the history view moves focus to search box.
* Debugger: Added c (compare memory) command.
* Debugger: Added a menu command to export the debugger help from the .help command in HTML form.
* Debugger: @hwwritereg(addr) can be used to read back write-only system hardware registers.
* Debugger: The debugger now additionally tries to resolve source file references against the module binary path and the paths of any open source windows.
* Debugger: Source windows now have context menu options to reopen the file externally.
* Debugger: u (unassemble) now has -m option to change CPU mode used for disassembly.
* Devices: 1030 now does actual pulse/tone dialing.
* Devices: 1030 relay sound is now heard when phone is placed on-hook.
* Devices: Added SIDE 3.1 (JED 1.4) support.
* Devices: Added CPS SuperSALT Test Assembly support.
* Devices: MidiMate now exposes a serial port for custom MIDI interfacing.
* Devices: File writer device can now also be used with serial ports.
* Devices: Added networked serial port device.
* Devices: Added copy/paste support to devices UI.
* Devices: Added shortcut command to rescan a virtual FAT16/FAT32 disk.
* Devices: Added 835, full 835, and full 1030 hardware emulation.
* Devices: Added SIO serial adapter device to bridge serial devices directly to the emulated SIO bus without requiring motor control activation.
* Display: Added support for main display pan and zoom.
* Disk: Improved timing compensation when burst I/O mode is enabled.
* Input: Added support for Chalk Board PowerPad controller.
* Input: Added support for Stack Lightpen controller.
* Input: Mouse wheel can now be bound as an input.
* Input: Added an option to show pointer location when driving a tablet, pad, or light pen/gun with a non-mouse input.
* Input: Pad input area can now be moved and resized via Configure HUD.
* Network: Raised max MSS in emulation TCP stack from 512 to 1460.
* Network: Emulation gateway now supports ICMP echo requests (only to the gateway; not forwarded).
* Network: Emulation gateway now has a more distinctive Ethernet address to avoid conflicts when bridging through a VXLAN tunnel.
* PerfAnalyzer: Added support for saving and loading traces.
* PerfAnalyzer: Added trace channel for disk sectors passing under the drive head.
* PerfAnalyzer: Added approximated import for Atari800WinPLus 4.0 monitor execution traces (TRON/TROFF).
* Save States: Devices can now opt-in to save state support.
* Save States: R-Time 8, XEP80, Black Box, MIO, Ultimate1MB, SIDE/2/3, and MyIDE[-II] are now included in save states.
* Save States: CPU mode, 65C816 high memory, and Axlon memory are now included in save states.
* System: Added 1400XL and 1450XLD emulation support (currently only minimal V:/T: support).
* UI: Added /registeruserfileassocs, /registersysfileassocs, and /unregisterfileassocs for silent registration/unregistration of file type associations.
* UI: Added support for screen readers to read out text from the emulation screen (opt-in).
* VFS: Added support for reading from .zip files that use Enhanced Deflate compression.
* VFS: Add special:// protocol to access specific images.

[bugs fixed]
* AltirraOS: Fixed incorrect MEMLO adjustment when loading peripheral handlers through CIO via type 4 poll.
* AltirraOS: Force C=1 on exit from CIO for compatibility (undocumented behavior).
* AltirraOS: Shift+Help and Ctrl+Help are now reported properly in HELPFG.
* AltirraOS: KEYREP and KRPDEL are now supported properly on the 65C816 build.
* AltirraOS: Improved compatibility of NOCLIK handling.
* AltirraOS: Fixed K: not applying inverse video to vertical bar ($7C) character.
* AltirraOS: Fixed timing issue in SETVBV.
* AltirraOS: S: now properly overrides the no-clear flag for GR.0.
* AltirraOS: FASC no longer clears first byte of FR0.
* AltirraOS: SIOV now resets BRKKEY when returning Break key pressed condition.
* Audio: Fix downmix setting not saving.
* Cartridge: Phoenix and Blizzard cartridge types now also react to CCTL reads as well as writes.
* Cartridge: SIC! 128K and 256K images now retain their original type rather than being converted to 512K on load.
* Cassette: Fixed FLAC decoder crashing on some files on some CPUs.
* Cassette: BASIC auto-boot detection now handles BASIC programs saved with the rev. B BASIC bug.
* Cassette: SIO data in line is now released when motor stops.
* Command line: Address specified in /soundboard switch was always overridden to default.
* CPU: 65C816 PLB and PLD instructions were not setting NZ flags.
* CPU: 65C816 PHP instruction could write bits 4/5 as zero after re-entering emulation mode from native mode with MX bits cleared.
* CPU: Improved accuracy of NMI timing when NMIs occur across a write to WSYNC.
* Custom Devices: Programmatic memory layer changes no longer bypass auto-PBI.
* Debugger: Zero page symbols were not being loaded from CC65 symbols.
* Debugger: PEI (dp) instruction no longer shows indirect data in disassembly.
* Debugger: Symbol lookup is now suppressed for (dp), (dp,X), and (dp),Y addressing modes with D != 0 like with other direct page addressing modes.
* Debugger: Fixed Step Over command not working above bank 0.
* Debugger: Disassembler now does basic block detection in 8048 mode.
* Debugger: Fixed .diskdumpsec command not working on virtual disks.
* Debugger: Fixed a crash when clearing breakpoints from debugger symbol based assert/trace directives.
* Debugger: Fixed panes that displayed the context menu at the wrong place when activated from the keyboard.
* Debugger: Debug display wasn't decoding IR mode 8 properly.
* Debugger: Improved visibility of keywords in source views in dark theme.
* Devices: R-Time 8 is now reset on a cold reset.
* Devices: SIDE 2 now returns floating bus data instead of $FF when reading from deselected CF card.
* Devices: Fixed sporadic initial interrupt state issue with MIO.
* Devices: Fixed some stack wrapping bugs with Veronica's 65C816 CPU.
* Devices: Fixed "use long path names" setting not saving properly on the H: device.
* Devices: H: no longer returns Y=$03 for imminent EOF when reading directories.
* Devices: MIDI output device from MidiMate is now reset on cold reset.
* Devices: Added missing emulation of IDE+2 CF detect in $D1FA bit 6.
* Devices: Fixed virtual FAT32 device limiting included files to FAT16 cluster limit.
* Devices: Fixed 8048 ADDC,@Rn and MOVP3 A,@A instructions and TF emulation.
* Devices: Fixed broken ATI0/1 commands for SX212.
* Disk: Fixed XF551 full drive emulation sometimes not handling write protect state properly.
* Disk: Reinterleave command wasn't marking the disk as modified.
* Disk: Fixed crash when attempting to convert a disk using an unknown or unsupported filesystem.
* Disk: Improved Happy 1050 memory map to closer match hardware, including contended regions.
* Disk: Add workaround for ATX disk images that have extra zero padding words at the end.
* Disk: Fixed 810, 1050, and XF551 based full drive emulators not consistently acting on write protect status.
* Disk: Improved accuracy when reading and writing sectors with missing data fields.
* Disk: Fixed rotational position being updated while motor is off.
* Disk: Fixed 810 post-read delay being used for 1050 emulation in single density.
* Disk: Improved timing precision for full disk drive emulators.
* Disk: Sectors are now ignored on mixed-density disks when not using the current density.
* Display: Fixed inverted field polarity detection in interlace mode (since 3.90) and improved auto-flip behavior.
* Display: Removed horizontal offset in PAL high artifacting.
* HLE: Set Y and C=1 in program loader to emulate CIO results when invoking init/run address.
* Input: Fixed paddles not responding when driven in absolute mode from a digital input (regression since 4.10).
* Input: Fix light pen not working in port 4.
* MMU: Extended RAM priority is now adjusted when U1MB is enabled to emulate difference in VBXE MEMAC behavior.
* Network: Fixed emulation TCP stack not sending final FIN packet to emunet after graceful shutdown from remote host.
* Network: Emulation dhcpd no longer reports a gateway to DHCP clients if routing is disabled (NAT off).
* Network: Fixed VXLAN tunnel code sending two extraneous bytes with each Ethernet frame.
* PerfAnalyzer: Fixed keyboard shortcuts not working in the perf analyzer's history view.
* PerfAnalyzer: Snapshot frame timing at end of session so VBI/DLIs don't get confused when emulation is restarted after the trace ends.
* PerfAnalyzer: Fixed crash in tape code after stopping trace with a tape mounted.
* POKEY: Improved accuracy of truncated/restarted POTGO scans.
* POKEY: Fixed stop bits not playing properly out audio channels 1/2 in two-tone mode.
* Recorder: Fixed bug with AVI writer not marking all uncompressed frames as key frames.
* Recorder: Fixed incorrect colors when recording WMV or MP4 video without scaling (ARM64 only).
* Save States: Fixed POKEY having keys stuck down after loading a save state.
* Save States: Fixed last 64K of extended memory not being saved properly in 128K and 320K memory modes.
* UI: Fix crash when using Calibrate Screen command without any hardware graphics acceleration.
* UI: Ensure that undocked tool windows are on-screen when restoring window layout.
* UI: Added workaround for Windows 10/11 touch keyboard sending the wrong extended key state for movement keys.
* UI: Fixed Input Setup controller diagrams displaying blank in some configurations.
* VBXE: Fixed incorrect blitter cycle speed for $00 bytes transformed by AND/XOR mask.
* VBXE: Blitter collision detection now returns the first hit instead of the last hit.
* VBXE: Fixed pixel shadows when using HR blit mode (mode 6).
* VBXE: Fix false P/M priorities on right half of screen in core 1.26 in lines that have no P/M graphics.