SCSI: DB-25
Serial Ports: 2
Sound Output: stereo 8 bit.
ADB: 2
Ethernet: AAUI-15
Machine Gestalt ID: 36
PRAM Battery: 3.6V lithium (Maxell ER3S, Radio Shack 23-026)

Minutiae:

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. 

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.