8" drives produce FM at 250Kbps or MFM at 500 Kbps.

The UART, in mode0 should be able to manage a 2 MHz sampling of that rate with plenty of time for the MCU to manage other tasks like moving the assembled bytes to XRAM while polling the index/sector signal to find the sector pulses and operate a timer to separate them from the index pulse, which occurs on the same signal.

I'd sayu that the easy way to do this is to buffer it in SRAM and, when the track ends, transmit it to the PC in bursts via USB by means of the FTDI DLP245UM.

RE