Questions Beginners Ask

Tom R. Halfhill, Features Editor

Are you thinking about buying a computer for the first time, but don't know anything about computers? Or maybe you just purchased a computer and are still a bit baffled. Each month in this column, COMPUTE! will answer some questions commonly asked by beginners.

Q I'm looking around for my first personal computer, and am wondering if I should get an 8-bit or 16-bit computer. I don't really understand the difference, except I was told by a salesman that 16-bit computers are faster, have more memory, and will eventually replace 8-bit computers. Is this true? Are 8-bit computers becoming obsolete? Would I be better off with a 16-bit computer? What is the real difference, anyway?

A These questions come up fairly often, so let's deal with them in some detail.

First, it's not true that 8-bit computers are becoming obsolete. Most of the computers being sold today are 8-bit computers, especially the under-$1000 home computers. Although it is true that 16-bit computers will likely become increasingly common, 8-bit machines (especially in the low price range) will be around for a good while.

Nor is it true that 16-bit computers are necessarily faster or contain more memory.

The difference between 8- and 16-bit computers lies in their Central Processing Units. The CPU is the central "brain" of a computer. It fetches instructions written by programmers, performs arithmetic to execute the instructions, and stores the results of its calculations in memory. The CPU controls or oversees all the operations performed by the computer. Without a CPU, a computer would be a brainless collection of memory chips, support chips, and wires.

In very large mainframe computers, the CPU might be a unit the size of a refrigerator, made up of dozens of circuit boards. Microcomputers (including personal computers) have a microprocessor CPU – a CPU that fits on a single silicon chip smaller than a penny. Microprocessors work strictly with binary numbers (1's and O's). All instructions and numbers required for calculations must first be converted to groups of binary numbers before the microprocessor CPU can handle them.

Some microprocessors are designed to handle groups of binary numbers only four digits long. That is, all numbers and instructions must be broken up into groups of four 1's and O's, such as 1101 or 1011. This would be called a 4-bit microprocessor (a bit is a binary digit – a 1 or a 0). Portable calculators use these 4-bit chips.

Other microprocessors are more powerful and can handle numbers and instructions in groups of eight 1's and O's. These are 8-bit microprocessors. A 16-bit microprocessor handles 16 bits at a time, a 32-bit microprocessor handles 32 bits, and so on.

Generally speaking, the larger these groupings (called word size), the more powerful the computer. Computers which handle numbers internally in larger chunks of bits can work faster and more efficiently. Also, they generally have more memory because they are designed to run larger programs and therefore need more memory.

But keep in mind that these are general rules, and, as always, there are exceptions. Several other factors also determine the speed of a computer and the amount of memory it contains.

For instance, the only 16-bit home computer now on the market is the Texas Instruments TI-99/ 4A. Its maximum memory expansion is 48K, which is no more (and in some cases less) than the maximum memory available in such 8-bit computers as the Commodore 64, Apple II/IIe, Atari, Radio Shack TRS-80, Timex/Sinclair, etc. Also, most of these 8-bit computers can run BASIC programs somewhat faster than the TI-99/4A.

In one benchmark test we heard about, a small 8-bit Timex/Sinclair 1000 actually outran a larger and much more expensive 16-bit IBM Personal Computer. Yet, a business person who needs the powerful features of an IBM PC would not want to choose the T/S 1000 on the basis of speed alone.

That's why you shouldn't base a buying decision solely on the question of 8-bit versus 16-bit. Too many other factors are important. Instead, carefully evaluate your own needs, and then shop for a computer and software combination that serves them well.