How fast can a 6502 transfer memory?
This also misses loop unrolling, combined with an assembly language version of "Duff's device" to be able to do an arbitrary number of transfers even if your loop is unrolled to, say, 8 transfers.<p>This stuff used to matter!  I had an NCR5380 chip on an Amiga, simple, memory mapped I/O, no DMA or interrupts.  To get a tape drive to stream (remember that?) the byte transfer loop really had to be tweaked.  But once fully tweaked, "whoooooooosh" instead of "chugga chugga chugga".<p>And truly heroic programming techniques had to be employed on the C64 to do X/Y smooth scrolling games.  Often a static part of the screen, conveniently displaying scores etc, existed to make it work - there was just enough bandwidth to do 80% of the screen, say, so you find an excuse to keep the rest of it static.<p>I kinda miss those days, and I kinda don't.  I guess it was good to have experienced them.