Four SIMM sockets. Upgraded with one SIMM at a time. Ships with one OR two 8MB SIMM(s) installed. This computer comes with 2048K ROMs and an Apple 1.44MB SuperDrive. Serial Port with the phone icon supports synchronous modems, with handshaking on both both output and input supported. The Quadra 840AV contains the 66MHz AT&T 3210 DSP chip. Sound output is 16-bit stereo. This computer has an international power supply. It does not support 1MB, 2MB SIMMs.