Hardware of LED Interface

8 Leds

The most basic system. Simply connect 8 Leds to D0-D7 on the parallel port. Don't forget a resistor of about 200 Ohms!

             ____
2 D0 -------|____|----|->-----+
             ____             |
3 D1 -------|____|----|->-----+
             ____             |
4 D2 -------|____|----|->-----+
             ____             |
5 D3 -------|____|----|->-----+
             ____             |
6 D4 -------|____|----|->-----+
             ____             |
7 D5 -------|____|----|->-----+
             ____             |
8 D6 -------|____|----|->-----+
             ____             |
9 D7 -------|____|----|->-----+
                              |
18 GND -----------------------+

12 Leds

As the parport has 12 output pins, I recommend you build this version. The leds should are aligned the pins on the 25pin D-Sub connector. Some parports seem to source the control pins 1, ... less than the data pins, so you may need 200 Ohm resistors for D0-D7 and some smaller resistors for the control pins.

             ____
1 Strobe ---|____|----|->-----+
             ____             |
2 D0 -------|____|----|->-----+
             ____             |
3 D1 -------|____|----|->-----+
             ____             |
4 D2 -------|____|----|->-----+
             ____             |
5 D3 -------|____|----|->-----+
             ____             |
6 D4 -------|____|----|->-----+
             ____             |
7 D5 -------|____|----|->-----+
             ____             |
8 D6 -------|____|----|->-----+
             ____             |
9 D7 -------|____|----|->-----+
             ____             |
14 Autofd --|____|----|->-----+
             ____             |
16 Init ----|____|----|->-----+
             ____             |
17 Select --|____|----|->-----+
                              |
18 GND -----------------------+

32 Leds