"The emulator also has a fun hack for disk performance I'm hoping will get replicated in some of the upcoming retro 65C816 board design. Like the 6502 the 65C816 sucks at continually reading from an MMIO port and writing it to sequential memory locations. It sucks less than a 6502 because you've got 16bit index registers, but at the same clock it was doing about 100K/second that a Z80 can do 250K (with ini loops). The revised emulated disk interface has the same mmio port replicated across a chunk of address space and this allows a block move instruction (MVN) to do all the work at 6 clocks/byte. At that point the 65C816 suddenly jumps to twice as fast as the Z80 on disk I/O."
"The emulator also has a fun hack for disk performance I'm hoping will get replicated in some of the upcoming retro 65C816 board design. Like the 6502 the 65C816 sucks at continually reading from an MMIO port and writing it to sequential memory locations. It sucks less than a 6502 because you've got 16bit index registers, but at the same clock it was doing about 100K/second that a Z80 can do 250K (with ini loops). The revised emulated disk interface has the same mmio port replicated across a chunk of address space and this allows a block move instruction (MVN) to do all the work at 6 clocks/byte. At that point the 65C816 suddenly jumps to twice as fast as the Z80 on disk I/O."