How Transistors Manipulate Data

THE transistor is the basic building block from which all microchips are built. The transistor can only
create binary information: a 1 if current passes through, or a 0 if current doesn't pass through. From
these 1 s and Os, called bits, a computer can create any number as long as it has enough transistors
grouped together to hold all the 1 s and Os.
Binary notation starts off simply enough:
Decimal Number Binary Number Decimal Number Binary Number
0 0 6 110
1 1 7 111
2 10 8 1000
3 11 9 1001
4 100 10 1010
5 101
Personal computers, such as the original IBM PC and AT systems based on the Intel 8088 and 80286 microprocessors,
are 16-bit PCs. That means they can work directly with binary numbers of up to 16 places, or bits. That
translates to the decimal number 65,535. If an operation requires numbers larger than that, the PC must first break
those numbers into smaller components, perform the operation on each component, and then recombine the results
into a single answer. More powerful PCs, such as those based on the Intel 80386, 80486, and Pentium, are 32-bit
computers, which means they can manipulate binary numbers up to 32 bits wide-the equivalent in decimal notation
of 4,294,967,295. The capability to work with 32 bits at a time helps make these PCs much faster and capable of
directly using more memory.
Transistors are not used simply to record and manipulate numbers. The bits can just as easily stand for true (1) or
not true (0), which allows computers to deal with Boolean logic. ("Select this AND this but NOT this.") Combinations
of transistors in various configurations are called logic gates, which are combined into arrays called half adders,
which in turn are combined into full adders. More than 260 transistors are needed to create a full adder that can
handle mathematical operations for 16-bit numbers.
In addition, transistors make it possible for a small amount of electrical current to control a second, much stronger
current-just as the small amount of energy needed to throw a wall switch can control the more powerful energy surging
through the wires to give life to a spotlight.