M65 C65 emulator differences explained
Currently, Xemu contains two "targets" (ie emulation targets): for Commodore65 (C65) and Mega65 (M65).
More information: main article about C65 emulation of Xemu
For the C65 emulator, the goal is to emulate a C65 without any M65 feature, maybe even at the price having incompatibility with M65, if there is some C65-M65 difference at all. C65 emulation is much more simple, requires lower resources, and some different internal structure of the emulator fits better than implementing M65. Currently, the C65 emulator can handle D81 disk images directly, specified from the command line. Access is limited to read-only for now.
C65 emulator can "boot", can go into "C64 mode", and some software like the "K2 demo" partially runs at least.
More information: main article about M65 emulation of Xemu
Though M65 emulator was basically a fork of the C65, it strongly diverges into another direction, because of:
- more and differently organized features, even if they seem compatible with each other from the surface
- the stronger need of debug tools for M65 development which at the other hand, requires "deeper" level of things too
Since then, the internal structure of M65 emulation is a big hack now, and will be rewritten, but it's clear, that another solution fits better than for the C65 emulator (and what is almost the same in VHDL, it's maybe not the best for a software emulation, IMHO).
M65 emulator is currently targeted for "kickstart development" and check, not for "generic" emulation of M65, which may not be even possible (even at C65 CPU clock speed, it eats about the 20% of a CPU time of a modern PC, and this emulation is not even close to be perfect, ie screen is max 640*200 pixels, and 25Hz screen refresh frequency is used ... surely, several things can be done better, but I doubt, it will reach 48MHz emulated CPU speed with decent VIC-IV emulation in full resolution, at full refresh rate ...).
M65 emulation targets for now the minimal feature set of M65 to be able to "boot" using an image file of an SD-card, with even upgrading the hypervisor ("kicked"), etc. M65 emulation does not use discrete D81 images but SD-card emulation oriented instead.
