More or less what I was trying to say (however clumsily). For more conversation on transfer loop speeds, see my comments on Herb Johnson's Retrotechnology site. By getting clever with code, you can turn in some pretty fast transfer loops even on a lowly 2 MHz 8080. For example, if we assume that the controller will assert wait states if an input is attempted on the data port until a byte becomes available and interrupts on operation complete, a 2MHz 8080 transfer loop could handle an 8" MFM transfer like this: LXI H,floppy$byte floppy$byte: clocks 2mhz IN fdcport ;FDC port 10 5 uS PUSH PSW ;store 2 bytes 11 5.5 uS PCHL ;loop 5 2.5 uS Total: 26 13 uS Now, of course, you've got to unravel what you've got on the stack to get your data back, but you've gotten it--at 2MHz and on an 8080 yet. Caveat: I haven't tried this, except on paper. If you were to unroll the loop to a series of IN/PUSH pairs, the byte time should drop to 10.5 usec, more than fast enough for an 8" MFM transfer. But that discussion's from the days when silicon was expensive. An inexpensive async FIFO would get rid of the problem entirely and allow for transfer at one's convenience. The point that I was trying to make was that the 1770/2/3 make for very easy interfacing with a minimum of parts--and are very easy to program. They feature a small package and were designed for 5.25"/3.5" drives. Were I prototyping a small PCB with a Z80 and floppy support, they'd be my first choice. Cheers, Chuck