Four SIMM sockets.  Upgraded two SIMMs at a time.

Comes with 1MB of RAM, consisting of four 256K SIMMs.

On a Plus when 1MB SIMMs are installed, the 256KBIT 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 256K SIMM in position 3 and 4. 

Comes with 128K of ROM and a 800K floppy drive.

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.

Sound output is mono.

Does not have an international power supply.