Apple sometimes advertises this as a 66 MHz machine, since the clock speed is doubled inside the processor chip. However, all I/O to the processor is done at 33 MHz.
Sound output is 16-bit stereo for CD playthrough. Sound output is 8-bit for Macintosh generated sounds. Front headphone jack is 16-bit stereo.
Serial Port with the phone icon supports synchronous modems, with handshaking on both output and input supported.