Supported System Software: 1.1 through 7.0.1, 7.1, 7.5, 7.5.1, 7.5.3
SCSI: DB-25
Serial Ports: 2
Sound Output: mono 8 bit.
ADB: none
Ethernet: none
Machine Gestalt ID: 4

Minutiae:

Shipped with 1MB of RAM, consisting of four 256 KB SIMMs.

Upgraded two SIMMs at a time.

On a Plus when 1MB SIMMs are installed, the 256KB resistor must be clipped to enable recognition of the higher density SIMMs.  A 2.5MB configuration has a 1MB SIMM in positions 1 and 2 and a 256KB SIMM in position 3 and 4. 

Serial Port with the phone icon in the Plus does not support synchronous modems.  It only supports handshaking on the output, not on the input.

Has 128KB of ROM and a 800KB floppy drive.