Mainframe vs. Personal Computer
...e or two hard drives, with 40 Gigabytes of hard drive space each, and 256 to 512 MB of RAM. Mainframes on the other hand, can come with hundreds of hard drives in a sophisticated array and, typically, gigabytes of memory. You are able to purchase a PC at a computer store, or even on the Internet, for as little as $200.00 and have a relatively powerful machine. In contrast, to purchase a Mainframe, you generally need to custom-order it from the manufacturer. The cost can be in the millions. Software Software is another key difference. Most PCs will run Windows and function as Clients in a network environment while Mainframes exist only as Servers and typically run some form of UNIX/Linux or Z/OS. On the user's PC, you may install a new version of Windows every few years and most of your desktop products need to be upgraded. On the server, you install a new release of Unix and your database server needs to be upgraded. In addition you will upgrade your database product and most of your application packages for accounting, inventory, etc. Installing these products can be extremely time consuming and can cause a lot of downtime. Mainframe applications, on the other hand, seldom change and when updates are applied there is generally no downtime. Down time is an important factor because it can be very costly to companies – not to mention the possibility of corruption or loss of data. Comparisons There are many variables when comparing and contrasting the differences between PC's and Mainframes, including performance, reliability, and cost. In terms of CPU speed, oddly enough, the difference is not as vast as it once was. In this day and time, the differences lie mainly in reliability and Input/Output capabilities. Mainframes have a much larger I/O bandwidth than PC's. Mainframes also have a lot of redundancy and serviceability features automatically built in. A mainframe’s handling of I/O is much more efficient than the PC boxes. Also, instead of one pathway into memory – as in a PC – there are multiple memory banks providing multiple ports into memory. Compared to a PC, mainframes may have up to three times the bus speed, 10 times the cache speed, perhaps 32 or 64 overlapped data transfers. Multiply one times the other, and the combination makes a processing machine unlike anything else. When we compare the reliability of mainframes and PC's, the mainframe wins hands down. The main reason is the mainframe’s history of stability and uptime, meaning it is rarely, if ever, down. This amazing stability is the product of about 34 years of mainframe research and development. Thirty years is a long time for companies to perfect their systems and create a very formidable machine. PC’s, in contrast, have a much greater amount of down time and are only at the beginning of incorporating successful software, which will monitor its hardware and can report errors. Purchasing When you look at the price you need to look at a lot of things. Number of users, amount of work to be done by the computer, number of support personnel per user. A single NT-run server is cheaper than a single mainframe, however you may need a lot of NT-run servers to do the same amount of work as a single mainframe. The number of employees potentially using the computer is generally a major consideration. If a company has several o...