Supported System Software: 7.1, 7.1.1(Pro), 7.5, 7.5.1, 7.5.3
SCSI: DB-25
Serial Ports: 2
Sound Output: stereo 16 bit.
ADB: 1
Ethernet: AAUI-15
Machine Gestalt ID: 60

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.