SCSI: DB-25
Serial Ports: 2
Sound Output: stereo 8 bit.
ADB: 2
Ethernet: AAUI-15
Machine Gestalt ID: 53
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 one SIMM at a time. 

Has the Apple 486SX PDS card.  See PC Compatibility Card section in GURU.

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.