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A shopping list for microcomputer hardware.

A shopping list for microcomputer hardware

Buying a microcomputer system is not a simple task. A great variety of hardware and software is often sold in parts that have to be put together like a jigsaw puzzle. If you are not careful, you could buy parts of different puzzles. They may squeeze together, but you will have an odd-performing whole rather than the efficient system you sought.

Making the appropriate decision on an item and learning how to use it may cost more money in terms of personnel time than the item itself does. For that reason, most organizations with more than five computer users should have a person who advises them on computer purchases and uses.

My purpose here is to provide a checklist of the items you need to purchase. This column will deal with the microcomputer itself; next month I will discuss attachments. Software will be the subject of two Computer Dialog columns early next year.

In previous articles, I recommended the purchase of IBM-compatible microcomputers (or clones) and explained how to convert your organization to them if you currently have assorted computer models.1-4 There are two basic configurations for IBM-type microcomputers: PC/XT and AT compatibles. The PC and XT use an 8088 or 8086 microprocessor, while the AT uses the 80286 microprocessor. The type of microprocessor determines the internal structure and speed of the computer and what kind of programs can be run.

The main differences between the PC and XT are that the XT, like the AT, usually has a hard disk (fixed to the computer in most cases, faster and with much larger capacity than a floppy disk), and some XTs have a bigger power supply than the PC. You can add a hard disk to a PC, however.

In fact, many differences among PCs, XTs, and ATs have become blurred through improvements in technology. For example, the AT used to be faster than the PC, but one can now buy accelerator cards that bring the PC close to AT performance.

A computer may be bought as a fairly complete product from a single manufacturer or as parts to be assembled from one or more manufacturers. The parts include:

The "motherboard' or basic computer structure. This consists of random access memory (RAM), which is fast electronic memory; the microprocessor or central processing unit; and a variety of circuitry for internal and external computer connections.

Disk drive. A couple of common configurations are 1) two floppy disk drives and 2) one floppy and one hard disk drive (usually referred to as the XT configuration).

Keyboard. Most often the user gets the keyboard the manufacturer has selected, but it is possible to buy a different one. Users who assemble their own computers obviously make the keyboard choice themselves.

Display driver, commonly called the display card or display board. These electronics are used to display information on the screen of a monitor. A text-only driver displays only letters, numbers, and symbols. The text, of very high quality, is usually monochrome. A graphics driver displays graphics and text in monochrome or color. Sometimes its text is lower in quality than that of a text-only driver. Recent graphics cards have excellent text quality, however, and I recommend their purchase since they cost the same as text-only cards or boards. Monochrome drivers generally have higher resolution and cost less than color drivers.

Monitor. Apart from whether the monitor is monochrome (often green or amber) or color, key differences are in size and resolution.

Interfaces. Two commonly used interfaces let your computer communicate with other machines. The parallel interface provides a connection with a printer. The serial interface--RS 232 is the most common type--connects one computer to another with cable or through a telephone using a modem. It also connects a computer with a printer.

In summary, a basic computer should have two disk drives or one disk drive and one hard disk, a keyboard, 256K or more RAM, one serial RS 232 interface and one parallel interface, a display card, and a monitor.

Competition has driven prices down. In the following brief rundown, the prices are approximate and can go lower with discounts or when vendors have sales:

IBM PC compatible with two disk drives, a monitor plus monochrome graphics driver, keyboard, and 256K RAM: $1,800 for an IBM, $1,200-$1,500 for other major brands, and $900 for a lesser known brand. A color driver costs $100 to $800 extra, depending on the number of colors and the resolution. A color monitor is $200 to $500 extra.

XT compatible with most of the same components but one disk drive and a 10 megabyte hard disk: about $400 more.

AT compatible with one disk drive (1.2 megabytes versus 360 kilobytes for the PC) and one hard disk: $2,500 to $4,500.

An alternative is to assemble your own computer by purchasing the major parts from stores. It's relatively easy: You can put the parts together with a few screws in about one hour; soldering is rarely required. In general, magazine reviews indicate that do-it-yourself computers are quite reliable. They are certainly cheaper, and you can also save money by performing your own repairs on simple breakdowns.

If you buy an IBM computer, you specify the display driver and monitor that you want. If you buy such other IBM-compatible brands as Tandy, Zenith, AT&T, Compaq, ITT, Leading Edge, and Epson, the computer usually comes with its own display driver and monitor as well as other built-in items, such as the parallel and serial interfaces. Some of these brands' display cards have better resolution than the IBM display cards.

Some PC/XT compatibles run 30 to 100 per cent faster than IBM PCs and XTs because they incorporate different chips and other technology needed for faster operation. Most computers now have a standard 256K of RAM; they used to come with 64K or 128K. The traditional maximum of 640K of RAM for the IBM PC or compatibles may now be expanded to 4,000K (4 megabytes) by using additional boards.

The XTs usually have a bigger power supply than the PCs, as do most PC/XT compatibles. That makes power supply problems less likely when you add peripherals.

Buying a PC compatible rather than an IBM PC, one also may obtain a lower price, free software, and a longer warranty. There's no IBM nameplate on the computer, though. In a large bureaucratized organization, the computer buyer is more likely to pick the IBM product. If problems arise, everyone will say he or she bought the best and is blameless. IBM compatibles are often found in smaller organizations, where the buyer is either the boss or accountable to fewer individuals.

The AT is approximately three times faster than traditional PC/XT models. Its disk drives store 1.2 megabytes. They can read the PC's 360-kilobyte disks but often cannot write into the 360K format.

For those who want a network of connected computers and require greater memory and speed, the AT holds significant advantages. If you perform complex mathematical calculations on real time (i.e., you need the results immediately), if you access a large data base and must have the answers as soon as possible (to answer phone inquiries, for example), or if you require extensive graphics, the AT is probably a better buy than the PC or XT.

Gas-liquid chromatography with a capillary column, as in toxicology, involves the kind of real-time calculations the AT is better suited for. Another example is determining whether a multichannel analyzer in use needs calibration. Speed is also important in interactive analysis, where the user must sit in front of the screen and wait for an answer before taking the next step.

On the other hand, if you plan to use the computer primarily for data entry or word processing, the PC or XT is more cost-effective than the AT. It is also more cost-effective if you need to have calculations performed but can wait for the results--overnight preparation of bills and routine reports, spreadsheet projections in budget planning, etc. Remember, you can purchase at least two PCs for the price of one AT, which could give you one computer for word processing and another for lengthy calculations.

As you can see, there are many considerations to juggle when you shop for a microcomputer. And we haven't even gotten into the many available attachments. That will be the subject of next month's column.

1. Siguel, E.N. Why the IBM PC? MLO 17(10): 97-98, October 1985.

2. Siguel, E.N. How to become IBM compatible. MLO 17(11): 97-98, November 1985.

3. Siguel, E.N. Tips on buying microcomputer hardware and software. MLO 16(9): 113-117, September 1984.

4. Siguel, E.N. The advantages of buying rather than writing software. MLO 16(8): 95, August 1984.
COPYRIGHT 1986 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1986 Gale, Cengage Learning. All rights reserved.

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Author:Siguel, Edward N.
Publication:Medical Laboratory Observer
Date:Sep 1, 1986
Previous Article:Earthquake! MT duty on a medical aid team.
Next Article:No more runaway health care spending.

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