Setting CPU Speed Displays on PC Cases

© 1998 by Bob Duhamel 

Figure 1: Seven Segment Display with segment labels.

 
Each segment of a Seven Segment Display is labeled as shown in figure 1. There is a jumper array for each digit of the LED display. Looking at the chart for setting the jumpers (which comes with the computer case) you will notice that each segment has a pin in the jumper array (labeled a through f). Also, each of the segment pins as has adjacent pins labeled 1, 2 and 3. This array will look something the following.

• 3 3 B 1 1 1 D 2 2 2 F 3 3 •
1 A 2 2 2 C 3 3 3 E 1 1 1 G 2

Placing a jumper from the segment pin to a number pin will cause that segment to light as follows.

1 = Normal
2 = Turbo
3 = Both

Placing a jumper from the segment pin to the pin labeled 1 will cause that segment to light when the computer is in the normal mode. Placing the jumper from the segment pin to the pin labeled 2 will cause the segment to light when the turbo button is in the turbo position. Placing the jumper from the segment pin the pin labeled 3 will cause the segment to light in both normal and turbo modes. To set the display to show "LO" and "HI" for the clock speeds the following settings are used.
 
 

Most Significant Digit Least Significant Digit
a = open 
b = 2 (turbo) 
c = 2 
d = 1 (normal) 
e = 3 (both) 
f = 3 
g = 2 
a = 1 
b = 3 
c = 3 
d = 1 
e = 1 
f = 1 
g = open

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