(DTMF) tones which are used by touch-tone phones to dial numbers. Telephone numbers in the address book can be speed-dialed by holding a telephone handset against the Portfolio's speaker.

Power is supplied by three AA size removable alkaline batteries. The computer's memory is preserved during battery changes. There is also an optional AC adapter (120V: HPC-401, 230V: HPC-402).The Portfolio's "DIP Operating System 2.11" is compatible with MS-DOS 2.11.