Connomore64: Cycle exact emulation of the C64 using parallel microcontrollers

Summary

Connomore64 https://github.com/c1570/Connomore64 Realtime cycle exact emulation of the Commodore 64 using multiple microcontrollers in parallel. This is a proof of concept and not end user ready. July 2024 poster (old prototype) In a nutshell, this is (or aims to be)… …a cycle exact Commodore 64 homecomputer emulator … … …an (almost) chip-by-chip rebuild using multiple RP2040/RP2350 microcontrollers (<1€ per chip!)… …interconnected using a multiplexed 8 bit bus running at about 8 MHz effectively… running at about 8 MHz effectively… …using DVI/HDMI as video and audio output… as video and audio output… …with microsecond exact true to original real world signal timing… …able to interface with original hardware … …such as the C1541 floppy drive, including fastloaders… …as well as userport and (some) expansion port based hardware. … Additionally, this is… …an example of running compute intensive software on cheap low powered interconnected microcontrollers … … …an emulation framework to test and debug projects using several RP2040/RP2350s in parallel on a PC. But why? First and foremost, this was started as a holiday project (“porting an existing C64 emulator to a 400MHz ARM platform cannot take that long, can it?”) with a focus on playing a bit with the RP2040 microcontroller and getting an idea of what its PIOs (i.e., its GPIO handling coprocessors) are capable of. The holiday of this “holiday project” was christmas 2022, and it turns out a single 400MHz M0+ core is definitely not enough to emulate a C64, if accuracy is some priority… While a C64 emulator on the RP2040 already exists, it is using an extremely simplified model of the C64, e.g., not emulating the exact steps and timing of MOS 6510 CPU opcodes, and not emulating the VIC-II video chip exactly but doing video line based emulation instead which limits compatibility. PC based emulators (VICE, BMC etc.) reach high emulation quality but do not feature perfect realtime timing. That means you cannot use physical ...