6o6 v1.1: Faster 6502-on-6502 virtualization for a C64/Apple II Apple-1 emulator
16 hours ago
- #retrocomputing
- #Apple-1 emulation
- #6502 virtualization
- Efficiency improvements made to 6o6 6502 virtualization library, including optimized addressing modes and a trimmed instruction in the hot path.
- Introduced a faster path for direct stores to the 6502 zero page, enhancing performance for zero page operations.
- Provided more control over the 6502 interrupt flag and updated documentation and examples.
- Released VA1 (Virtual Apple-1) emulator using 6o6, running on Commodore 64 and Apple II, with accurate Apple-1 emulation including video hardware timing.
- Discussed historical Apple-1 emulators like Mark Stock's Apple II version, Simon Owen's SAM Coupé version, and Green Delicious for Commodore 64, comparing their accuracy and implementations.
- Detailed Apple-1 hardware specifics, including video display mechanism using shift registers and character generation, based on schematics for emulation accuracy.
- Performance metrics: 6o6 1.1 executes 1,561,780,659 instructions for validation suite, a 2.6% improvement over v1.0, reducing average host instructions per guest instruction from 52.3 to 51.0.
- Future plans for 6o6 include fast path for stack operations and dynamic page table implementation to further optimize memory access.