Over the years computer technology has gone through many changes. Today there are numerous choices for an organization when deciding on a computer system to implement. Of course, many factors come into consideration with this decision such as, the size of the organization, the type of application, functional needs, and cost. There are small workgroups consisting of a handful of PCs, larger Client/Server configurations, midrange computer systems, such as the IBM AS/400, and mainframe computers. In this paper I will compare and contrast mainframes to PCs or microcomputers. The main topics I will discuss are performance and reliability, centralization, utilization, size and cost.

Large computers called mainframes prevailed many years ago when computer technology was first emerging. Today, mainframes are still in use in many organizations. These computers have many benefits to an organization. First, these massive computers are very fast. Processing power is what these computers are known for. They are optimized for large amounts input / output (IO) requests, and as a result, are capable of handling thousands of connections at one time without compromising performance.

Secondly, mainframes are designed to store large amounts of data. One of these computers is able to hold hundreds and even thousands of gigabytes of data making them ideal for database applications or data warehousing. Mainframes are very reliable also, usually having redundancy and fault tolerance with power supplies and disk drives, and system checking features informing operators of overall system health. Another advantage of using a mainframe is its centralized management. Connections to mainframes are usually a telnet session or some form a terminal emulation. The device accessing the computer could be what is called a "dumb terminal", which is basically a monitor and a keyboard that has a direct connection to the mainframe.

The device could also be a computer running an emulator to simulate one of these dumb terminal connections. The benefits of this environment are centralized control of administration, programming, and security. This centralization makes administering security, and programming upgrades easier, by only having to apply them to the mainframe and not each device. Also, many different types of computers can access the mainframe as long as there is an available emulator. There are some disadvantages to mainframe computers.

They are typically large computers, but as technology advances, their size is reducing. Many organizations do not have a room large enough with the appropriate temperature controls to store a mainframe. These computers are also very expensive. They can cost anywhere from hundreds of thousands of dollars to millions.

Another disadvantage of mainframes is that they are generally used for one purpose or one program. An organization like a bank or hospital may use a mainframe to run its core program and that is it. There is no other functionality to the system. Utilizing personal computers in an organization have many advantages. First, the processing power of PCs is increasing every year. It may be safe to say that a high end PC of today may have the processing speed of an early mainframe.

The amount of disk storage available to PCs is also increasing at leaps and bounds. Available storage is in the one hundred gigabyte range. Flexibility of personal computers is a big advantage. In the work place they can give an employee access to the organizations midrange or mainframe computer application, allow them to run client applications suites, and to communicate with coworkers through a mail client.

Also, the size of PCs seems to be shrinking year by year. A smaller personal computer is appealing as it takes up less space in an office. Finally, personal computers are inexpensive. A low end PC may cost an organization $800.

00 to $1, 000. 00, while a high end PC can cost anywhere from $2, 000. 00 to $3, 000. 00. Personal computers have some disadvantages also. Most PCs do not have any redundancy or fault tolerance built in.

If a power supply burns up, the computer will not function until your replace it. If a hard drive crashes, the data is usually unrecoverable. Another drawback to personal computers is its decentralization. If a company utilizes a network consisting of servers and PCs, each computer will have to be individually maintained. This maintenance can include hardware upgrades, software updates, and even some security. It is true that today's technology allows centralized management of networked computers for software and security deployment, but many organizations may to have this ability and each computer may have to be individually maintained.

As you can see, there are advantages and disadvantages to mainframes and personal computers. Deciding on a technology is depending on many factors including size of the organization, application, and cost. Both have their advantages and it takes an understanding of which one could be more fully utilized in an organization's environment. As technology advances with microcomputers and server-based computing, will mainframes may be a second choice to server farms and thin client technology?