SCSI: DB-25
Serial Ports: 2
Sound Output: stereo 8 bit.
ADB: 1
Ethernet: none
Machine Gestalt ID: 10
PRAM Battery: service center replacement only

Minutiae:

There were two version of the Portable.  The original Portable, released  9/89, came equipped with a non-backlit active matrix 1-bit (B&W) display.  The second Portable, released 2/91, came with a backlit version of the same display. 

In the non-backlit model, upgrades were with 2MB, 4MB, 6MB & 8MB memory cards.  In the backlit computers, upgrades were with 1MB, 3MB, 5MB & 7MB cards.

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

Has 256KB ROM and a 1.44MB SuperDrive.