This I/O board for the SYM-1 provides a female DB9 connector for RS-232 communication, a mono 3.5mm jack for cassette audio out (jumper configurable HI or LOW), a mono 3.5mm jack for cassette audio in and a 2.5mm jack for cassette remote control (jumper configurable for cassette decks Type I-VIII). This board requires a female DB-25 connector be soldered onto the T pins of the SYM-1 (I recommend DigiKey part number 1173-125FEA-ND).