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Table Of Contents  CertiGuide to A+ (Core Hardware)
 9  Appendix A:  Decoding Math

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Base 16

No law prevents us from counting in values other than base 2 or base 10. I'll bet that if we were born like some creatures from Star Trek and had 7 fingers and 1 thumb on each hand, we would balance our checkbooks in base 16 math. Base 16 looks like this:

1 = 1
2 = 2
3 = 3
4 = 4
5 = 5
6 = 6
7 = 7
8 = 8
9 = 9
A = 10
B = 11
C = 12
D = 13
E = 14
F = 15

Notice that a single column can be used for higher values than with base 2 or base 10. There is a bit of an issue with using base 16. Consider the value 278. In base 10 that is 2 hundreds, 7 tens, and 8 units. In base 16, that would not be the case, as the middle value is counted against 16, not 10. In base 10, the value is 70 (7x10). In base 16 the base 10 value is 112 (7x16). So, when writing values in base 16, it is considered best practice to put a little h after the value, such as 278h. Sometimes it is obvious it is in hex or hexadecimal when a value contains an alpha character between A and F, for example: 3F8(h).

Base 16 and there values are seen with memory values. The value 278h is the in/out (I/O) starting memory address for the second printer port (LPT2). The value 2F8h is the starting memory address for Com 1. All Network Interface Cards (NIC) need a memory address as well. Common NIC memory addresses are 300h, 320h, 340h, and 360h.

If after reading this several times it still sounds like some alien language, perhaps you could consider taking a trip to a local Radio Shack. Ask for their book that teaches basic electronics. It is inexpensive, and has a ton of easy to create experiments. With some fun experiments you will learn more about electronic components as well as the math and physics of electronics.

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