AT90S2313 PD0 - Serial receive PD1 - Serial send PD2 - Free Input/Output PD3 -\ PD4 | PD5 | 82C55 Addressing PD6 | PD7 -/ PB0 -\ PB1 | PB2 | PB3 | 82C55 Data PB4 | PB5 | PB6 | PB7 -/ 82C55 A0 -\ A1 | A2 | Stepper motor A3 | control A4 -/ A5 - Magnet control A6 - Scanning board enable (Active low) A7 - Free Output B0 -\ B1 | B2 | B3 | Scan input B4 | B5 | B6 | B7 -/ C0 -\ C1 | Scan control C2 | C3 -/ C4 - Limit switch 0 C5 - Limit switch 1 C6 - Free Input C7 - Free Input