Practice and communications systems: Part 2. Selecting computer hardware Martin N. Abelson, AB, DDS Rye, N.Y.
A n y advice offered to the reader on the subject of selecting computer hardware must, of necessity, be very genetic in nature. Specific recommendations cannot be made because of the meteoric way in which new developments are made, introduced, and become obsolete. Today's "best buy," or "most effective machine," is destined to be tomorrow's soon-to-be obsolete model. This article will cover only IBM compatible equipment. The reader can find a detailed discussion coveting the reasoning behind this choice in the first article of this series in the October issue of the JOURNAL. The original IBM personal computer had an Intel 8088, 8-bit microprocessor that ran at 4.77 MHz (megahertz). The next generation contained an 8088-2 processor that ran at about 7.8 MHz. In lime, 10 MHz then 12 MHz 8088 versions appeared. Before the 10 MHz and 12 MHz versions were introduced, the 8088 machines had long been obsoleted by the introduction of a series of Intel 80 286AT, 16-bit microprocessorbased machines that progressed in processor speed from early 10 MHz machines, then to 15 MHz, 20 MHz, and 25 MHz versions. During the evolution of the 286 machines, an 80386DX, 20 MHz machine with a 32bit microprocessor was introduced. Shortly after that, an 80386SX 16-bit microprocessor was introduced to compete with the 286 machines. The 386DX 25 MHz, 33 MHz, and 40 MHz machines soon became common. Meantime, an 80486DX microprocessor was introduced, as well as several completely new architecture designs for computers. Soon, an 80486SX was introduced; and so on and on and on. The transition from the simple 8088 to the 486 systems occurred in less than 5 years. During the same period, the capacities of floppy storage devices in common use, increased from 360 KB units to 720 KB, and then to 1.44 MB (Megabyte) units (a four-time increase). Now 4 MB floppy drives are becoming available. In the 8088 era, a 20 MB, 80-microsecond accessing speed hard drive was a desirable but exotic storage device used to speed
Diplomatc, American Board of orthodontists. 811139067
up program, data storage, and retrieval. Four and a half years later, the 130 MB 17 microsecond and 15 microsecond access speed hard drives had become almost standard equipment. The 1500 MB 13-microsecond hard drives had become available. Both the 130 MB hard drive and 1.44 MB floppy drives could be purchased at prices comparable to that paid for like devices in the 8088 microprocessor era. The same phenomenon occurred with memory chip capacity and costs. As machine capacities for memory, processing, and storage increased, software programs were produced to take advantage of these increases in capacity. First, new improved hardware is developed and introduced. Next, software is developed to take advantage of the newer capabilities. There seems to be a lag time of 1 to 2 years before a good assortment of software is available for newly developed capabilities. Once these facts of computer life are understood and taken into consideration, the following observations should prove helpful at any given time. A computer hardware system is basically comprised of the computer itself, a keyboard, a video monitor, and one or more printers. The computer is essentially a box that contains most of the hardware used to store and process data. The foundation is called a mother board, which has builtin circuits, sockets for a Bios chip, main microprocessor chip, numerical processor chip, expansion devices, memory chips, connectors for peripheral devices, and slots of different types to accept special purpose boards. The other major components are a power supply, floppy drives, hard drives, in/out (I/O) boards, controller boards, and a video processor board. The design of the mother board's built-in sockets, chips, and circuits set the limits of the maximum capabilities of the computer system produced. A mother board that contains 8-bit and 16-bit expansion slots can accept expansion devices designed for 8-bit or 16-bit machines. Such a mother board would not be capable of accepting and using a board designed to use 32-bit capabilities. Data are handled by a computer in bits that can be thought of as small chunks of information. A bit is comprised of eight pieces called bytes, rather like individual alphabet letters. Thus an 8-bit processor
471
4"12 Abelson
could process 64 letters at a time, whereas a 16-bit processor could handle 128, and a 32-bit processor 256, and so on. One also encounters the term computer bus. Think of the bus size as similar to a water pipe size. The bigger the bus, the greater the quantity of data bits that can pass through at any one time. A 386SX 20 MHz computer has a 16-bit bus, whereas a 386DX 20 MHz machine has a 32-bit bus. In both cases the processor type (386) and processing speeds (20 MHz) are the same, but the machine with a larger bus will handle more data faster because it moves it around through a larger pipeline. Just as the main microprocessor chip sets the processing capabilities of the computer, the Bios chip controls the environment and provides basic instructions that cannot be changed by the user. Unless a lot of number crunching operations are to be done, and the program being used supports a numerical processor chip, little is to be gained by installing one. In/Out (I/O) boards supply communication connections and capabilities with external peripheral devices, such as printers, telephone modems, mice, tape drives, CD ROM devices, musical keyboards, game controllers and other computers. Controllers for floppy and hard drives are sometimes built into a mother board, whereas others are installed on a card in an exapansion slot. Certain types of hard drives have built-in controllers. Some mother boards have built-in VGA video processors, whereas others use separate cards. Building capabilities into a mother board saves space and money and assures complete compatibility. On the other hand, these built-ins can cause problems if changes or upgrades to the technology are to be made or if defects in the mother board occur. Most IBM compatible computers come with at least one parallel port (usually used to connect a printer) and two serial ports. Serial ports can be used for printers, but serial communications are somewhat slower. Serial ports are used to connect most extemal devices such as modems, mice, and bridges to other computers. An internal modem installed in an expansion slot is less costly and neater. Mice are nice to have if you have programs designed to make use of them. They are not essential for orthodontic office application programs. Memory chips come in two types. Read only memory (ROM) such as in the Bios chip, and random access memory (RAM) in which data can be stored and changed, but in which the data are lost if the power is turned off. Since the ROM chips are dictated by the manufacturer, the reader should concern himself with RAM chips only. The RAM chips are used in d i f f ~ ' h t parts of a computer and for somewhat different purposes. These are conventional memory, extended mem-
Am. J. Orthod. Dentofac. Orthop. November 1992
ory, and machine memory. Conventional memory in an IBM compatible computer is limited to a maximum of 640K. The rated memory chip speed should match the capabilities of the microprocessor. Putting 60 nanosecond chips in an 8088 personal computer with an 8-bit microprocessor will not make an obvious difference in the overall performance. Generally speaking, use the fastest chips your machine can make use of. Bear in mind that the overall working speed of a computer is the product of many factors, hard drive access time, microprocessor speed, bus size, memory speed and management techniques, RAM caching, and application program design and size. Some machines are designed to use a relatively small but a very high speed (e.g., 20 nanosecond chips) RAM cache to enhance processing speed. These are often effective even if only 32K or 64K is provided. Many are expandable beyond the provided level, but such exapansion is not needed for general computing. Extended memory is discussed later on. The 8088 based personal computer was designed to run on the Microsoft DOS (disk operating system) system and had a system memory limitation of 640 KB of RAM. As machines and programs grew increasingly memory hungry, many approaches were taken to get around this 640K limitation. These approaches varied from experimentation with totally new or different operating systems, new hardware architecture, add on boards for older machines, software changes, software work-arounds, and combinations of several of these. Each approach was introduced with much fanfare and often, a great deal of controversy. Only the passage of time will provide the outcome. At the time this is being written, the largest available selection in software and hardware, and the most cost effective, still resides within the original DOS system. The recent introduction of DOS 5.0, a considerable improvement over earlier versions, may, to parapharase Mark Twain, cause reports of the death of DOS to be very premature. The DOS 5.0 system manages conventional memory far better than its predecessors, and it provides access to both expanded and extended memory. The 286AT machines and all their successors are capable of accessing expanded and extended memory beyond the 640K limitation. Add-on boards are available to expand even 8088 based machines so they can use expanded memory. There are at this juncture only a few programs that are capable of taking advantage of extended memory directly, but many application programs and shell programs are currently available that take advantage of expanded memory. Extended memory can be reconfigured as expanded memory. There seems to be no practical limit as to how much expanded and extended mem-
Volume 102 Number 5
ory can be installed either directly on the newer mother boards, or through add-on boards. Having a few megabytes of expanded memory available makes it possible to load any number of large applications into memory, and, through memory swapping, switch them back and forth between conventional memory for actual work and expanded memory for instant retrieval. The use of expanded memory has proven to be the most effective speed up approach even with the fastest microprocessors, hard drives, and memory chips installed. Over the years, the capacity of memory chips has been constantly increasing, whereas their physical size, current consumption, and cost have been constantly decreasing. The caveat for memory purchases is to lean toward the machine with the greatest built-in memory capacity, but only the memory you currently need for your current applications. Memory is easy to install and gets better and cheaper with the passage of time. Floppy drives for IBM compatible machines come in several sizes. It is useful to have a 5 1/4-inch high capacity drive so you can use all of the older programs. The newer 1.44 MB capacity 3 1/2-inch drives are a bit more useful for storage of back up copies of your data. They not only hold a little more data and take up less space, but they are also more solidly constructed. By having two drives it also facilitates copying disks. Hard drives are a major expense. Because they are a major purchase, they should be selected carefully. Basically, the faster they are, the quicker you can access and save data and application programs. As programs become more effective and versatile, they also become larger and require more storage space. My first word processing program could not only be run off a single 360K floppy disk, but the same disk also held the DOS operating system. WordPerfect version 5.1 and DOS version 5 take up four to five times as much storage space as their earlier versions did. In selecting a hard drive capacity, you can never have one too big or too fast. On the other hand, hard drives, as remarkably reliable as they are, do not last forever. It would be a shame to pay for capacity that never was put to use. It is possible to install a second hard drive internally or externally in a computer. Data compression programs are available that can at least double the storage capacity of a hard drive if the necessity should arise. A practical compromise is called for. Since hard drive prices, speed, and capacity are all linked, a relatively safe rule to follow is to purchase a hard drive with at least four times as much capacity as you think you will need. Monitors come in monochrome and color. For highest resolution at the lowest price, monochrome has always been the best choice. If the main use of a system
Special article 473 is for the production of text, and cost is important, go with monochrome. My preference is for the amber screen. Color has come a long way since the first red, green, blue (RGB) monitors were introduced for the 8088 IBM personal computers. Resolution was at best poor. The next level to appear computer graphics array (CGA) was an improvement overall, but did not even come close to T I ' L monochrome in quality. The introduction of VGA color began a new era. The VGA text resolution ability was quite acceptable. Early units were capable of 16 colors, later on there were 256 colors available if you had the memory capacity on the video board. At this writing, capabilities of 32,000 and 64,000 colors are readily available (S-VGA and UVGA) on noninterlaced (produces no obvious flicker) monitors with 0.25 mm dot pitch. The resultant images are stunning. If cost is not foremost and the reader wants to venture into color, I believe that the minimum entry level should be one of a VGA board with 512K memory expandable to I MB and an interlaced monitor with a maximum dot pitch of 0.31 mm. Bear in mind that a monitor can last for a long time. If in doubt, elect for the higher quality. It will be usable with your next computer. Keyboards come in a number of configurations. The most desirable placement of the function keys depends on the programs that will be used. Many users still prefer having the function keys arranged vertically down the left side rather than across the top. Keyboards are available that have both sets of function key placements. Separate cursor pad and number pad areas are helpful. Check to see if the keyboard has an acceptable tactile feel. Some keys are soft, others have a click when you hit them. My latest keyboard has all of these features, in addition to the ability to remap and program just about all of the keys. Most computers come with a mandatory keyboard. If a special set-up appeals to you, try to buy your computer separately. Selecting a printer presents an interesting problem. No one type of machine can do everything well, no matter what the cost. The evolution of printer technology has followed the hardware and software in pricing, flexibility, and functionality. Most offices will probably do best with two printers. At the time this article was written, a 24-pin dot matrix machine that is capable of producing near letter quality, and a basic model laser printer would be considered a very flexible combination. The dot matrix machine will accept multipart forms that require an impact printer. It will handle continuous paper for quick inexpensive production of bills and receipts, and it accepts all lengths and sizes of paper. Because of its near letter quality output, it can serve as an emergency replacement for the laser printer.
474
Abelson
Am. J. Orthod. Dentofac. Orthop. November 1992
The 24-pin dot matrix machines are inexpensive to purchase and to run. They are very flexible and offer a wide range of print fonts. In an office with a tight budget, a 24-pin dot machine can do it all. Their biggest draw back is that they are rather noisy. This can be handled by building an enclosure, putting the printer in another room, on a closet shelf, or by doing a minimal amount of printing when the office is active. Laser printers are also becoming more reasonably priced. They are very quiet and offer high quality output. Laser printers will produce the best communications image for an office. They are excellent for producing forms, including lines and shading. With proper memory expansion, they are the best printer for graphics, brochures, and newsletters. Paper handling is limited to smaller sizes, and some do not handle envelopes well. Memory boards, accessories, and supplies are expensive.
is not necessary or even practical, to purchase the most advanced version of the hardware. Software that takes advantage of the newest technology will be sparse. The most advanced version will usually cost almost twice as much as a practical "entry level" machine. A practical entry level should be defined as the fastest and most advanced technology readily available at the current time. All the hardware parts should be easily replaceable, and at a reasonable cost. All the software you have selected should be available and should be able to run well on the selected hardware. Expect that your new hardware will be sufficiently obsolete in about 5 years to warrant replacing most of it. Since you will have paid only about half as much as the top of the line would cost, you will later have sufficient funds left over to purchase a second machine that will be far superior to today's top of the line. You will also have the original computer for your home and children.
CONCLUSIONS
Reprhzt requests to: Dr. Martin N. Abelson 165 Polly Park Rd. Rye, NY 10580
Practical evaluations of computer parts have been provided. Suggestions have been offered to aid in the selection of computer hardware. After reviewing the past history of computer hardware purchasing and subsequent occurrences, my conclusions are as follows: It
A n y advice offered to the reader on the subject of selecting computer hardware must, of necessity, be very genetic in nature. Specific recommendations cannot be made because of the meteoric way in which new developments are made, introduced, and become obsolete. Today's "best buy," or "most effective machine," is destined to be tomorrow's soon-to-be obsolete model. This article will cover only IBM compatible equipment. The reader can find a detailed discussion coveting the reasoning behind this choice in the first article of this series in the October issue of the JOURNAL. The original IBM personal computer had an Intel 8088, 8-bit microprocessor that ran at 4.77 MHz (megahertz). The next generation contained an 8088-2 processor that ran at about 7.8 MHz. In lime, 10 MHz then 12 MHz 8088 versions appeared. Before the 10 MHz and 12 MHz versions were introduced, the 8088 machines had long been obsoleted by the introduction of a series of Intel 80 286AT, 16-bit microprocessorbased machines that progressed in processor speed from early 10 MHz machines, then to 15 MHz, 20 MHz, and 25 MHz versions. During the evolution of the 286 machines, an 80386DX, 20 MHz machine with a 32bit microprocessor was introduced. Shortly after that, an 80386SX 16-bit microprocessor was introduced to compete with the 286 machines. The 386DX 25 MHz, 33 MHz, and 40 MHz machines soon became common. Meantime, an 80486DX microprocessor was introduced, as well as several completely new architecture designs for computers. Soon, an 80486SX was introduced; and so on and on and on. The transition from the simple 8088 to the 486 systems occurred in less than 5 years. During the same period, the capacities of floppy storage devices in common use, increased from 360 KB units to 720 KB, and then to 1.44 MB (Megabyte) units (a four-time increase). Now 4 MB floppy drives are becoming available. In the 8088 era, a 20 MB, 80-microsecond accessing speed hard drive was a desirable but exotic storage device used to speed
Diplomatc, American Board of orthodontists. 811139067
up program, data storage, and retrieval. Four and a half years later, the 130 MB 17 microsecond and 15 microsecond access speed hard drives had become almost standard equipment. The 1500 MB 13-microsecond hard drives had become available. Both the 130 MB hard drive and 1.44 MB floppy drives could be purchased at prices comparable to that paid for like devices in the 8088 microprocessor era. The same phenomenon occurred with memory chip capacity and costs. As machine capacities for memory, processing, and storage increased, software programs were produced to take advantage of these increases in capacity. First, new improved hardware is developed and introduced. Next, software is developed to take advantage of the newer capabilities. There seems to be a lag time of 1 to 2 years before a good assortment of software is available for newly developed capabilities. Once these facts of computer life are understood and taken into consideration, the following observations should prove helpful at any given time. A computer hardware system is basically comprised of the computer itself, a keyboard, a video monitor, and one or more printers. The computer is essentially a box that contains most of the hardware used to store and process data. The foundation is called a mother board, which has builtin circuits, sockets for a Bios chip, main microprocessor chip, numerical processor chip, expansion devices, memory chips, connectors for peripheral devices, and slots of different types to accept special purpose boards. The other major components are a power supply, floppy drives, hard drives, in/out (I/O) boards, controller boards, and a video processor board. The design of the mother board's built-in sockets, chips, and circuits set the limits of the maximum capabilities of the computer system produced. A mother board that contains 8-bit and 16-bit expansion slots can accept expansion devices designed for 8-bit or 16-bit machines. Such a mother board would not be capable of accepting and using a board designed to use 32-bit capabilities. Data are handled by a computer in bits that can be thought of as small chunks of information. A bit is comprised of eight pieces called bytes, rather like individual alphabet letters. Thus an 8-bit processor
471
4"12 Abelson
could process 64 letters at a time, whereas a 16-bit processor could handle 128, and a 32-bit processor 256, and so on. One also encounters the term computer bus. Think of the bus size as similar to a water pipe size. The bigger the bus, the greater the quantity of data bits that can pass through at any one time. A 386SX 20 MHz computer has a 16-bit bus, whereas a 386DX 20 MHz machine has a 32-bit bus. In both cases the processor type (386) and processing speeds (20 MHz) are the same, but the machine with a larger bus will handle more data faster because it moves it around through a larger pipeline. Just as the main microprocessor chip sets the processing capabilities of the computer, the Bios chip controls the environment and provides basic instructions that cannot be changed by the user. Unless a lot of number crunching operations are to be done, and the program being used supports a numerical processor chip, little is to be gained by installing one. In/Out (I/O) boards supply communication connections and capabilities with external peripheral devices, such as printers, telephone modems, mice, tape drives, CD ROM devices, musical keyboards, game controllers and other computers. Controllers for floppy and hard drives are sometimes built into a mother board, whereas others are installed on a card in an exapansion slot. Certain types of hard drives have built-in controllers. Some mother boards have built-in VGA video processors, whereas others use separate cards. Building capabilities into a mother board saves space and money and assures complete compatibility. On the other hand, these built-ins can cause problems if changes or upgrades to the technology are to be made or if defects in the mother board occur. Most IBM compatible computers come with at least one parallel port (usually used to connect a printer) and two serial ports. Serial ports can be used for printers, but serial communications are somewhat slower. Serial ports are used to connect most extemal devices such as modems, mice, and bridges to other computers. An internal modem installed in an expansion slot is less costly and neater. Mice are nice to have if you have programs designed to make use of them. They are not essential for orthodontic office application programs. Memory chips come in two types. Read only memory (ROM) such as in the Bios chip, and random access memory (RAM) in which data can be stored and changed, but in which the data are lost if the power is turned off. Since the ROM chips are dictated by the manufacturer, the reader should concern himself with RAM chips only. The RAM chips are used in d i f f ~ ' h t parts of a computer and for somewhat different purposes. These are conventional memory, extended mem-
Am. J. Orthod. Dentofac. Orthop. November 1992
ory, and machine memory. Conventional memory in an IBM compatible computer is limited to a maximum of 640K. The rated memory chip speed should match the capabilities of the microprocessor. Putting 60 nanosecond chips in an 8088 personal computer with an 8-bit microprocessor will not make an obvious difference in the overall performance. Generally speaking, use the fastest chips your machine can make use of. Bear in mind that the overall working speed of a computer is the product of many factors, hard drive access time, microprocessor speed, bus size, memory speed and management techniques, RAM caching, and application program design and size. Some machines are designed to use a relatively small but a very high speed (e.g., 20 nanosecond chips) RAM cache to enhance processing speed. These are often effective even if only 32K or 64K is provided. Many are expandable beyond the provided level, but such exapansion is not needed for general computing. Extended memory is discussed later on. The 8088 based personal computer was designed to run on the Microsoft DOS (disk operating system) system and had a system memory limitation of 640 KB of RAM. As machines and programs grew increasingly memory hungry, many approaches were taken to get around this 640K limitation. These approaches varied from experimentation with totally new or different operating systems, new hardware architecture, add on boards for older machines, software changes, software work-arounds, and combinations of several of these. Each approach was introduced with much fanfare and often, a great deal of controversy. Only the passage of time will provide the outcome. At the time this is being written, the largest available selection in software and hardware, and the most cost effective, still resides within the original DOS system. The recent introduction of DOS 5.0, a considerable improvement over earlier versions, may, to parapharase Mark Twain, cause reports of the death of DOS to be very premature. The DOS 5.0 system manages conventional memory far better than its predecessors, and it provides access to both expanded and extended memory. The 286AT machines and all their successors are capable of accessing expanded and extended memory beyond the 640K limitation. Add-on boards are available to expand even 8088 based machines so they can use expanded memory. There are at this juncture only a few programs that are capable of taking advantage of extended memory directly, but many application programs and shell programs are currently available that take advantage of expanded memory. Extended memory can be reconfigured as expanded memory. There seems to be no practical limit as to how much expanded and extended mem-
Volume 102 Number 5
ory can be installed either directly on the newer mother boards, or through add-on boards. Having a few megabytes of expanded memory available makes it possible to load any number of large applications into memory, and, through memory swapping, switch them back and forth between conventional memory for actual work and expanded memory for instant retrieval. The use of expanded memory has proven to be the most effective speed up approach even with the fastest microprocessors, hard drives, and memory chips installed. Over the years, the capacity of memory chips has been constantly increasing, whereas their physical size, current consumption, and cost have been constantly decreasing. The caveat for memory purchases is to lean toward the machine with the greatest built-in memory capacity, but only the memory you currently need for your current applications. Memory is easy to install and gets better and cheaper with the passage of time. Floppy drives for IBM compatible machines come in several sizes. It is useful to have a 5 1/4-inch high capacity drive so you can use all of the older programs. The newer 1.44 MB capacity 3 1/2-inch drives are a bit more useful for storage of back up copies of your data. They not only hold a little more data and take up less space, but they are also more solidly constructed. By having two drives it also facilitates copying disks. Hard drives are a major expense. Because they are a major purchase, they should be selected carefully. Basically, the faster they are, the quicker you can access and save data and application programs. As programs become more effective and versatile, they also become larger and require more storage space. My first word processing program could not only be run off a single 360K floppy disk, but the same disk also held the DOS operating system. WordPerfect version 5.1 and DOS version 5 take up four to five times as much storage space as their earlier versions did. In selecting a hard drive capacity, you can never have one too big or too fast. On the other hand, hard drives, as remarkably reliable as they are, do not last forever. It would be a shame to pay for capacity that never was put to use. It is possible to install a second hard drive internally or externally in a computer. Data compression programs are available that can at least double the storage capacity of a hard drive if the necessity should arise. A practical compromise is called for. Since hard drive prices, speed, and capacity are all linked, a relatively safe rule to follow is to purchase a hard drive with at least four times as much capacity as you think you will need. Monitors come in monochrome and color. For highest resolution at the lowest price, monochrome has always been the best choice. If the main use of a system
Special article 473 is for the production of text, and cost is important, go with monochrome. My preference is for the amber screen. Color has come a long way since the first red, green, blue (RGB) monitors were introduced for the 8088 IBM personal computers. Resolution was at best poor. The next level to appear computer graphics array (CGA) was an improvement overall, but did not even come close to T I ' L monochrome in quality. The introduction of VGA color began a new era. The VGA text resolution ability was quite acceptable. Early units were capable of 16 colors, later on there were 256 colors available if you had the memory capacity on the video board. At this writing, capabilities of 32,000 and 64,000 colors are readily available (S-VGA and UVGA) on noninterlaced (produces no obvious flicker) monitors with 0.25 mm dot pitch. The resultant images are stunning. If cost is not foremost and the reader wants to venture into color, I believe that the minimum entry level should be one of a VGA board with 512K memory expandable to I MB and an interlaced monitor with a maximum dot pitch of 0.31 mm. Bear in mind that a monitor can last for a long time. If in doubt, elect for the higher quality. It will be usable with your next computer. Keyboards come in a number of configurations. The most desirable placement of the function keys depends on the programs that will be used. Many users still prefer having the function keys arranged vertically down the left side rather than across the top. Keyboards are available that have both sets of function key placements. Separate cursor pad and number pad areas are helpful. Check to see if the keyboard has an acceptable tactile feel. Some keys are soft, others have a click when you hit them. My latest keyboard has all of these features, in addition to the ability to remap and program just about all of the keys. Most computers come with a mandatory keyboard. If a special set-up appeals to you, try to buy your computer separately. Selecting a printer presents an interesting problem. No one type of machine can do everything well, no matter what the cost. The evolution of printer technology has followed the hardware and software in pricing, flexibility, and functionality. Most offices will probably do best with two printers. At the time this article was written, a 24-pin dot matrix machine that is capable of producing near letter quality, and a basic model laser printer would be considered a very flexible combination. The dot matrix machine will accept multipart forms that require an impact printer. It will handle continuous paper for quick inexpensive production of bills and receipts, and it accepts all lengths and sizes of paper. Because of its near letter quality output, it can serve as an emergency replacement for the laser printer.
474
Abelson
Am. J. Orthod. Dentofac. Orthop. November 1992
The 24-pin dot matrix machines are inexpensive to purchase and to run. They are very flexible and offer a wide range of print fonts. In an office with a tight budget, a 24-pin dot machine can do it all. Their biggest draw back is that they are rather noisy. This can be handled by building an enclosure, putting the printer in another room, on a closet shelf, or by doing a minimal amount of printing when the office is active. Laser printers are also becoming more reasonably priced. They are very quiet and offer high quality output. Laser printers will produce the best communications image for an office. They are excellent for producing forms, including lines and shading. With proper memory expansion, they are the best printer for graphics, brochures, and newsletters. Paper handling is limited to smaller sizes, and some do not handle envelopes well. Memory boards, accessories, and supplies are expensive.
is not necessary or even practical, to purchase the most advanced version of the hardware. Software that takes advantage of the newest technology will be sparse. The most advanced version will usually cost almost twice as much as a practical "entry level" machine. A practical entry level should be defined as the fastest and most advanced technology readily available at the current time. All the hardware parts should be easily replaceable, and at a reasonable cost. All the software you have selected should be available and should be able to run well on the selected hardware. Expect that your new hardware will be sufficiently obsolete in about 5 years to warrant replacing most of it. Since you will have paid only about half as much as the top of the line would cost, you will later have sufficient funds left over to purchase a second machine that will be far superior to today's top of the line. You will also have the original computer for your home and children.
CONCLUSIONS
Reprhzt requests to: Dr. Martin N. Abelson 165 Polly Park Rd. Rye, NY 10580
Practical evaluations of computer parts have been provided. Suggestions have been offered to aid in the selection of computer hardware. After reviewing the past history of computer hardware purchasing and subsequent occurrences, my conclusions are as follows: It
