Commodore 64 Emulator v0.8.8.5-alpha is released. A Commodore 64 emulator written in modern C++, built with SDL2 and designed around two priorities:Accuracy-first emulation (with a strong focus on real hardware behavior over “good enough” hacks); Debuggability (integrated monitor, break/watchpoints, and visibility into what the machine is doing). This project is actively under development; expect rough edges and incomplete features.

Commodore 64 Emulator Changelog:
Commodore 64 Emulator — v0.8.8.5-alpha
This release introduces Commodore 2031 floppy drive emulation, adds IEEE-488 support, and delivers significant improvements to disk operations, hardware accuracy, save states, and debugging capabilities.
The ML Monitor now supports both IEC and IEEE-488 drives through a unified debugging interface. Additional improvements include new disk image formats, expanded cartridge compatibility, and numerous reliability fixes.
🚀 New Features
Commodore 2031 Floppy Drive Emulation
Introduced emulation of the Commodore 2031 IEEE-488 floppy disk drive.
Added 2031 drive ROM loading, memory mapping, CPU execution, and dual MOS 6522 VIA support.
Implemented IEEE-488 communication, device addressing, and drive mechanics.
Integrated the 2031 into the emulator's drive management, user interface, and debugging systems.
Added support for IEEE-488 device addresses 8–11.
Added disk loading, formatting, and writing functionality.
IEEE-488 Bus Support
Introduced an IEEE-488 bus implementation with controller and peripheral device support.
Added IEEE-488 cartridge integration and TPI 6525 support.
Implemented IEEE-488 signal handling, device notifications, and bus state management.
Added IEEE-488 bus monitoring, watchpoints, and breakpoint support.
Improved bus timing, signal transitions, and device communication.
Expanded Disk Image Support
Added G64 disk image support for the 1541 and 1571.
Added G71 disk image support for the 1571.
Introduced initial read-only NIB disk image support, including improved track extraction and revolution detection.
Added DMP image loading support.
Improved handling of raw GCR tracks and nonstandard disk layouts.
Additional Cartridge Support
Added IEEE-488 cartridge emulation.
Added Protovision MegaByter support.
Added BMP Data Turbo 2000 support.
Added SD-BOX support.
Added Rex RAM-Floppy support.
Added MultiMAX support.
Added Game Killer support.
🔧 Improvements
Drive Emulation and Disk Operations
Improved continuous GCR recording and disk formatting for the 1541 and 2031.
Improved 1571 GCR byte delivery, write timing, and disk rotation behavior.
Consolidated GCR encoding, decoding, and density timing into shared components.
Improved disk media access through shared raw track interfaces.
Improved 1571 native-mode disk handling and timing.
MOS 6522 VIA Emulation
Consolidated shared MOS 6522 VIA functionality used by supported drives.
Improved VIA port registers, control pin behavior, interrupt handling, and shift register operations.
Improved Peripheral Control Register (PCR) output handling.
Improved VIA save/load state accuracy.
Improved 2031 VIA signaling and hardware control behavior.
ML Monitor and Debugging
Unified drive debugging for IEC and IEEE-488 devices.
Added bus-independent drive CPU inspection and stepping.
Added bus-independent drive memory dumps and VIA debugging.
Expanded drive watchpoint management across both bus types.
Improved drive summaries and bus-specific signal reporting.
Added IEEE-488 bus commands and expanded diagnostic output.
Save/Load State Reliability
Expanded 2031 save/load state coverage.
Improved restoration of GCR track data, disk position, and internal drive state.
Improved IEEE-488 bus and TPI 6525 state handling.
Improved VIA state restoration and control signal consistency.
User Interface and Media Management
Added 2031 floppy drive options when an IEEE-488 cartridge is attached.
Restricted available drive types to those compatible with the currently active bus.
Automatically removes incompatible drives when switching between IEC and IEEE-488 configurations.
Improved drive activity reporting and idle-state behavior.
Centralized media error handling across supported media formats.
🐛 Bug Fixes
Commodore 2031
Fixed duplicate bytes during IEEE-488 SAVE operations.
Fixed SO signaling through VIA2 CA2 control.
Fixed continuous GCR recording and D64 formatting.
Fixed disk loading behavior that could trigger unnecessary disk writes.
Fixed save-state restoration that could unintentionally modify disk images.
Fixed IEEE-488 device addressing.
Fixed drive UI sector indicators continuing to cycle while idle.
Commodore 1541 / 1571
Fixed continuous GCR recording and D64 formatting on the 1541.
Fixed 1571 GCR write sequencing and byte-ready handling.
Fixed 1571 VIA interrupt acknowledgment behavior.
Improved 1571 native-mode D64 reads.
Fixed several disk timing and signal-handling issues.
General Stability
Fixed drive compatibility handling when switching bus configurations.
Improved IEEE-488 breakpoint and watchpoint processing.
Improved cartridge-related state restoration.
Improved emulator shutdown cleanup.
Improved disk write-protection handling.
Improved error reporting for disk images, cartridges, tapes, and program loading.
📌 Release Notes
This is an alpha release. Some hardware emulation features, particularly newer IEEE-488 and Commodore 2031 functionality, may still require additional testing and refinement.
The primary focus of this release is expanding hardware compatibility while improving the accuracy, reliability, and debugging capabilities of the emulator.
Version: v0.8.8.5-alpha
Previous Version: v0.8.7.6-alpha

Download: Commodore 64 Emulator v0.8.8.5-alpha
Source: Here