3. CPU Speaker Monitor Printer Touch pad Scanner Key Board Mouse Microphone

4. Input Output Input Output Input All these devices can be divided in to two categories Process

5. Motor ? ? Light Bulbs or LEDs Water Censer Light Censer (LDR) Micro Switch Temperature Censer (Thermister) ?

6. Parallel Port ( Printer Port) USB (Universal Serial Bus) RS232 (Serial Port) GPIB (Genaral Purpose Interface Bus) Speaker Microphone Line In Various types of connecters (communication ports) available in rear side of CPU

7. 10 0 10 1 10 2 10 3 11000100 10 1000 * 0= 0 100 * 1= 100 10 * 6= 60 1 * 4 = 4 = 164 Decimal Binary We use Ten Symbols 0 1 2 3 4 5 6 7 8 9 2020 21212 2323 184 8 * 1 = 8 4 * 1= 4 2 * 0 = 0 1 * 1= 1 = 13 We use Two Symbols 0 1 or Off On or Low Hi or 0V 5V 2 1 6 4 1 1 0 1 2

8. Output Data 1 Data 0 Data 2 Data 4 Data 5 Data 3 Data 6 Data 7 ACK Busy Paper Empty Select StrobeInput 1 14 13 25 Initialize Printer Auto Feed Error Select Input Pins 18 – 25 Ground Output Input 8 Data Outputs (378 H) 4 Other Outputs (379 H) 5 Data Inputs (37a H)

9. 1 14 13 25 - + 5V VCC 470 ohm LED Printer Port Example in Qbasic Out &H378,1 (for LED off) Out &H378,0 (for LED on) Example in Qbasic Out &H378,1 (for LED off) Out &H378,0 (for LED on)

10. 1 14 13 25 LED 470 ohm 5 V D0 D1 D7 D2 Printer Port

11. Number Output Data bit pattern D7 D6 D5 D4 D3 D2 D1 D0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 2 0 0 0 0 0 0 1 0 3 0 0 0 0 0 0 1 1 4 0 0 0 0 0 1 0 0 5 0 0 0 0 0 1 0 1 6 0 0 0 0 0 1 1 0 … 255 1 1 1 1 1 1 1 1 0 = 0V (Low state) 1 = 5V (High state)

12. IN+ IN- Comparator ¼ LM339 R4 3.3kohm 12V VCC R2 100kohm R3 10kohm From Printer Port R5 R1 10kohm 3.3kohm D400 1N4007 D1 X Y K2 RELAY 5 2 4 230 V AC L N 230V AC Motor

14. 1 14 13 25 Printer Port Switch we can use Qbasic function inp() X = Inp( &H379) Print X we can use Qbasic function inp() X = Inp( &H379) Print X 10 25

15. 100 k Preset IN+ IN- Comparator 10kohm 12V To Printer Port Input 100kohm 5 2 4 5.6kohm ¼ LM339 LDR 1 M Preset