SCSI: DB-25
Serial Ports: 2
Sound Output: stereo 16 bit.
ADB: 1
Ethernet: AAUI-15
Machine Gestalt ID: 60
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 50MHz AT&T 3210 DSP chip.

Serial Port with the phone icon supports synchronous modems, with handshaking on both output and input supported.

Has 2MB ROM and a 1.44MB SuperDrive.