SCSI: DB-25 Serial Ports: 2 Sound Output: stereo 8 bit. ADB: 2 Ethernet: optional Machine Gestalt ID: 30 PRAM Battery: 3.6V lithium (Maxell ER3S, Radio Shack 23-026) Minutiae: Apple sometimes advertises this as a 50 MHz machine, since the clock speed is doubled inside the processor chip. However, all I/O to the processor is done at 25 MHz. Upgraded with one SIMM at a time. Memory can be interleaved for approximately 10% faster RAM access. For the fastest speed, sockets 1 & 2 or 3 & 4 should contain the same capacity SIMM. Serial Port with the phone icon supports synchronous modems, with handshaking on both output and input supported. Has 1MB ROM and a 1.44MB SuperDrive.