Computer Buyer's Glossary

Last updated 1998 July 9 Roedy Green © 1997-1998 Canadian Mind Products.
He who controls vocabulary controls thought.
Luigi Wittgenstein

Overview

This document defines terms used in advertisments for computer hardware. It is primarily about WinTel (Widows/Intel) computers, though some of it also applies to other platforms. The definitions are not always strictly accurate because they have been simplied for the first time computer buyer. First time buyers should ignore any sentences that begin "Technically ...". That is information for more advanced computer users.

If you come across a term in a computer advertisement not listed here, or any errors or omissions, please send me an email at roedy@mindprod.com.

Please excuse me, I have just started this, so most of the definitions are missing.

The Glossary

16-bit
Windows 3.1 programs process information two characters (or 16 bits at a time) at a time. To handle numbers bigger than 32,767, they must break the number up into pieces, and process each piece separately. Programs must be broken into chunks no bigger than 64K (65,536 characters). See 32-bit
32-bit
Windows-95 programs process information four characters (or 32 bits at a time. Thus they can handle numbers up to 2,147,483,648 as a single chunk. There is no practical limit on program size.
386sx
An Intel CPU. See CPU.
386
An Intel CPU. See CPU.
40486
An Intel CPU. See CPU.
486
An Intel CPU. See CPU.
AMD
a competitor to Intel that makes compatible CPUs. Some may soon be sold under the IBM brand name.
Apple
A company that makes a competive line of computers with completely different software from Windows. Apple MacIntoshes are based on the Motorola 68000 line of CPUS and IBM RISC PowerPC line.
applications
Applications or (apps for short) are programs written for some specific purpose, for example a word processor, a spreadsheet or a desktop publishing program. In contrast, the general purpose program that manages all the applications is called the operating system. Windows-95, Windows 3.1, OS/2, NT, NeXT, Linux, and Unix are common operating systems that all run on PCs.
ATA
AT Attachment (Interface specification for IDE disks, named after the PC/AT where IBM first used these things.) There a couple of improvements on the ATA standard to support larger disks, non-disk devices, and higher speeds. They named ATA-2 and ATA-3. Ultra-ATA and ATA-4 are in the works.
backup
see mag tape backup
BBS
Bulletin Board System. A computer with dial up phone lines. They allow group discussions, and electronic mail. The two main problems with BBSes are:
  1. getting a busy because all its lines are in use.
  2. You can't phone one in another city without paying long distance.
The Internet does not have these limitations, and has made the BBS all but obsolete.
BIOS
Basic Iput Output System. Your computer contains a permanent small uneraseable program burned into it stored in ROM chips. This program handles the very basic functions needed to get Windows-95 started. The BIOS can accept a keystroke, put a character on the screen, read the floppy, read the hard disk or tell the time of day.
bus
The various i/o cards (video controller, internal modem, sound card, SCSI controller etc.) inside the computer communicate with each other, the RAM and the CPU via a common set of wires embedded in the motherboard. The original XT used 62 conductors. Slots are the holes in the motherboard where you insert the i/o cards. Slots with only the original 62 connections are called ISA (Industry Standard Architecture) 8-bit slots because they allow the devices to transfer one character (8 bits) at a time, one bit over each wire. It sounds crazy that of 62 conductors, only 8 carry data and the rest are for housekeeping, but that's the way it is. The AT computer introduced an additional 36 connections for a total of 98. Slots with 98 connections are called ISA 16-bit slots. They can transmit data 2 characters (16 bits) at a time. Then evolved various experiments at extending the bus further including IBM's MCA bus (Microchannel Architecture), the VESA bus (Video Electronics Standards Association) and the EISA bus (Extended Industry Standard Architecture). All of these fizzled in the market place. Intel then invented the PCI bus (Peripheral Component Interconnect) which uses a great many tiny connectors. Such slots are called PCI 32-bit slots. A 64-bit PCI bus is in the works. Most modern PCs have 3 or more PCI slots plus 3 or more 16-bit ISA slots.
cache
Cache three meanings. It comes from the French cacher to hide.
  1. SRAM cache is some high speed SRAM where the most active data in DRAM are duplicated. SRAM can be accessed in about 10 nanoseconds (billionth of a second) where ordinary DRAM takes about 60 nanoseconds, six times slower than SRAM. In advertisements "256K cache" refers to this SRAM. It is usually 128K to 1 MB. Most CPUs also have a small ultra fast SRAM cache built right into the chip that augments the external cache. It is typically only 4 to 32K.
  2. Windows-95 duplicates the most active parts of the hard disk in a DRAM cache. A fast hard disk takes about 6 milliseconds (thousands of a second) to access, about 100,000 times slower than DRAM. Windows automatically decides the size of this cache, carved out of your ordinary RAM. It is usually about 1 to 2 MB. This extreme speed differential is why adding more DRAM is so effective in speeding up your computer. Windows-95 does not function well on less than 16 MB, and does better with 32 MB.
  3. Any time some higher speed storage is used to store the most active parts of some slower speed medium.
case
The bigger the case the easier it is to service, and the more room for expanision -- with bays for adding extra a extra disk, tape drive, CD-ROM, floppy, DVD etc. Most computers nowadays come in mini tower cases that can fit on the floor desktop.
CD-R
Compact Disc Recordable. A CD-ROM drive that lets you create your own CDs, or copy existing ones, computer or audio. The CDs you create cannot be erased and reused. The blanks cost about $2 US each. See CD-RW, multiread.
CD-ROM
Compact Disc Read Only Memory. Computer programs come written on discs that look just like ordinary audio CDs. They can hold about 600 MB of data, or the equivalent of 400 floppy diskettes. A computer CD-ROM drive is much like one in a home stereo, except that it spins 2X, 4X, 8X, 12X, 16X or even 24X as fast. The faster it spins, the faster data can be read. With the appropriate cable, you can even play audio CDs on a computer CD-ROM drive. Digital CDs can be read, but not written on. This means there is no practical way to brand them with your name, or even with a serial number. Often a magic password comes with a CD, on a piece of paper you are bound to lose. Without the password, you can't install (or re-install) the software. Use a Sharpie permanent marker to write the password/serial number/key on the top side of the CD where you can't lose it. Don't apply any sort of sticky label since it may come off inside the drive. The two most common kinds of CD-ROM are EIDE and SCSI. Unfortunately there are also several other proprietary types that cause nothing but trouble often bundled with sound cards. See DVD, CD-R, CD-RW, multiread.
CD-RW
Compact Disc Rewriteable. A CD-ROM drive that lets you create your own CDs, or copy existing ones, computer or audio. The blanks can be erased and cost about $18 US each. Usually the process of writing the reusable blanks is much slower than non-eraseable ones. UDF software such as DirectCD lets you treat the CD-RW as a giant floppy, adding to it a bit at a time. Most drives are either pure CD-ROM, or combination of CD-ROM, CD-R and CD-RW. See CD-R, multiread.
CDRAM
Cache Dynamic Random Access Memory. 100 MHz RAM.
CGA
Colour Graphics Adapter. An antique video card that gave low-resolution colour.
click
to point at something on the screen with the mouse and press the left mouse button.
CMOS
Complementary Metal Oxide On Silicon. A tiny 128 byte memory that does not lose its contents when the power is off. There is a battery to keep it working. It stores crucial configuration information such as the types and sizes of your hard disk, floppies, and RAM. If you use ordinary dry cells, you will lose the memory after a year. If you use a lithium battery it should last about 5 to 7 years. CMOSSave makes a copy of your CMOS on floppy and hard disk so that if it is ever corrupted or lost, you can restore it.
Colour Wax Printer
Colour wax printers are too expensive for most home users. They melt coloured wax to form very vivid images.
continuous forms
Laser and inkjet printers print on single cut sheets, usually 8.5x11. A dot matrix printer works best with very long sheets of paper, folded and perforated between pages with tractor holes along the side to keep it straight. Continuous forms sometimes have mulitparts with a carbon or with NCR carbonless 2nd and 3rd copies. Laser and inkjet printers cannot handle multipart forms.
CPS
Characters Per Second. This is a measure of printer speeed. 70 CPS is roughly equivalent to one page per minute.
CPU
The CPU is the part of the computer that does the calculations. A clock beats out a rhythm like a slave driver in a Roman oar-driven ship. The CPU does some calculation on each beat of the clock. The faster the clock beats the faster the work gets done. Roughly speaking then a 200 MHz CPU (the clock beats 200,000,000 times a second) will work twice as fast as one that works at 100 Mhz. In practice the whole computer will be considerably less than twice as fast because the other parts of the computer e.g. the RAM, hard disk etc. are no faster. Different CPU chips, even at the same clock rate, perform differently. More expensive CPU chips are designed to do more work per clock beat. They may do this by clever circuitry or by taking bigger hunks of data to process at once, or by doing more than one calculation per clock beat. Here are the Intel line of CPU chips used in MS-DOS/Windows personal computers ordered from slowest to fastest. People tend to focus too much on raw CPU speed. More RAM, faster hard disk, a smarter video card, faster RAM, or a bigger SRAM cache are often better places to spend your money to get an overall faster computer.
Intel chip bits grabbed
at once
bits calculated
at once
8088 (XT) 8 16
8086 16 16
80286 16 16
80386sx 16 32
80386dx 32 32
80486 32 32
Pentium (586) 64 32
Pentium Pro (686) 64 32
Pentium II (796) 64 32
CRT
Cathode Ray Tube. On a desk top computer this is the screen. Laptops use LCD panels instead. See monitor.
DAO
Disc At Once. In DAO format, the CD-ROM disc is created in one continous write. This format can be read by all platforms and all CD-ROM drives. To create this format often requires additional cost Nero 3.0 software, or CD Pro 95 version 2.11c. Without DAO, you may be limited to Win95/NT and/or places where special readers and software are installed.
Direct RDRAM
Direct Rambus Dynamic Random Access Memory. 500 MHz memory that should be showing up in 1998.
DDR-SDRAM
Double Data Rate Synchronous Dynamic Random Access Memory. Also known an SDRAM II, an enchanced form of SDRAM.
DMA
Direct Memory Access. PCs have a pair of tiny computers in addition to the main CPU. They are quite stupid. All they can do is arrange to send data from RAM to an i/o device or vice versa. The advantage is, they can do this without requiring much help from the main CPU. This frees the main CPU to do more useful work. Most of the time you can forget about DMA. However if you install a sound card, you may have to assign the card some DMA channels that don't conflict with any other device in your machine. In theory, Plug & Play sound cards will automatically select unused DMA cards, but does not always work. Each device that wants to use DMA needs its own private channel. Each controller can keep four "conversations" going at once. Each conversation gets assiged to a channel number. Here is how the DMA channels are assigned:
Channel width in bits Use
0 8 used to refresh DRAM memory
1 8 default low DMA for Sound Blaster card, used by a SDLC card
2 8 diskette drive
3 8 free, often used by a sound card.
4 8 cascade, a kludge to hook the two DMA controllers together.
5 16 default high DMA used by a Sound Blaster card.
6 16 free, often used by a sound card.
7 16 free
The ordinary slow style DMA is called 3rd party DMA because the DMA controller acts as a third party to mediate between two other devices (usually RAM and a peripheral). Because these built-in DMA controllers are so slow and so ineptly designed, sometimes a PCI card or ISA SCSI card will provide its own replacement high speed DMA controller that runs at full bus speed. This is called first party DMA. The standard DMA controller is so incredibly slow that, PIO is faster for hard disk access. See PIO.
dot matrix printer
a printer that uses tiny wires pressed into a ribbon to make the image.

The advantages are: The disadvantages are:
DRAM
Dynamic Random Access Memory is the garden variety RAM used to store the currently active programs and data. Technically it is usually fast-page, meaning once a row is accessed, only the column need be updated.
DSK
Dvorak Standard Keyboard. See Dvorak.
DVD
Digital Video Disk. This is the technology that will replace CD-ROMS. DVD packs much more information onto a disc. DVDs will allow games with large amounts of high quality graphics, music and video. They will also allow entire movies to be put on a single disc. The standards still have not shaken out. We are still in the Betamax vs VHS stage.
Scheme Capacity Notes
DVD-Video 4.7 GB Time-Warner, Disney, MGM/UA etc. backing.
Divx n/a scheme to allow game or video rental
DVD-R 4.7 GB write once
DVD-RAM 2.6 GB/side
DVD+RW 3.0 GB/side compatible with DVD-RAM
Dvorak
A keyboard layout that lets you type considerably faster without wrist strain. Instead of the usual QWERTY layout, the keyboard is laid out like this with the most common keys in the home row (vowels on the left, consonants on the right), the less common in the upper row, and the least common in the bottom row. A friend at the Worker's Compensation Boards said eventually lawsuits over repetitive strain injuries will force employers to switch to Dvorak. I personally found touch typing with QWERTY too painful. For more information see my essay on DSK.
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ECP
Enhanced Capacity Port. A faster bi-directional parallel port. This allows the printer to interrogate the printer. A normal parallel port only allows the computer to send information to the printer, not the reverse, except for few bits of printer status. The bi-di port can also be used by LapLink to tie two computers back to back. An ECP port uses a DMA channel which allows you to efficiently send information to a printer without pestering the CPU with an interrupt for every character sent. See EPP.
EPP
Enhanced Parallel Port. A faster bi-directional parallel port. This allows the printer to interrogate the printer. A normal parallel port only allows the computer to send information to the printer, not the reverse, except for few bits of printer status. The bi-di port can also be used by LapLink to tie two computers back to back. See ECP.
EIDE
Enhanced Integrated Drive Electronics. The most common method for attaching hard disks and CD-ROMs to the computer. The alternative is SCSI. SCSI is more expensive, but is no faster if you use Windows-95. SCSI is faster if you use OS/2 or NT. EIDE uses ribbon cables with 40 conductors. You can't connect a SCSI drive to an EIDE controller or vice versa. Most modern PCs have two EIDE adapters. Each one can handle two devices, one designated as the master and the other the slave. You must configure jumpers on the devices to select standalone master, master with slave or slave.
EISA
see bus.
EDO RAM
Extended Data Out Random Access Memory. This is a faster style of DRAM used in some Pentium class machines. It gives about 10% more speed. Technically, it makes makes incremental alterations to DRAM access patterns, allowing data read during one access to remain valid while another read is taking place.
EGA
Extended Graphics Adapter. An antique video card that produced only 16 colours.
ESDI
Extended Small Disk Interface. an antique style of hard disk controller.
ESDRAM
Extended Synchronous Dynamic Random Access Memory. An enhanced form of SDRAM
Ethernet
You can connect computers together to let them share files, printers, or programs. Ideally you connect them in a star using 10-base T wiring, that looks like fat 8-conductor telephone wire with oversize clear plastic phone jack plugs. At the center of the star is a little box with indicator lights called a hub. The other technique is to snake a single coax cable (called ThinNet) through all the computers. Coax suffers from the same problem that cheap Christas tree lights do. If any link is not perfect, the whole system goes down. The advantage of coax is you need less wire altogether and you don't need to poke around in the ceiling threading wire all the way back to the hub to add another workstation. Ordinary Ethernet can transmit 10 million bits per second, about 1/8 the speed you can access data off a good quality hard disk. There are various Ethernet variants that allow you to transmit 100 million bits per second. For heavy duty applications there are now Ethernets capable of a gigabit per second, i.e. 1000 million bits per second. See LAN.
FaxModem
A faxmodem is a modem that can also act as a fax machine. The fax feature usually only costs a very few dollars more. Mainly you use the faxmodem to send unsigned documents generated on your word processor. To send paper documents, or to sign documents you need a scanner. You can view the fax documents on the screen, or if you have a printer, you can make hard copy. There are two kinds of faxmodem, class 1 and class 2. Class 1 are dumb, class 2 are smart. Class 1 are more flexible. Class 2 modems can usually also act as Class 1. Sometimes you will find your modem works in Class 1 mode better than it does Class 2. Class 1 and Class 2 have nothing to do with Group 1 and 2 and 3 and 4 used to classify fax machines. See modem, scanner.
Flash BIOS
Ordinary BIOS is permanent, set at the factory. Flash BIOS for all practical purposes is also permanent, but it can be upgraded by running a special program. See BIOS, ROM.
floppy
Floppy disks (sometimes called stiffies, diskettes, floppies or floppy diskettes) are used for transporting data and programs between computers, often through the mail. When you buy small software programs, they will often come on a few floppy disks. However, large programs like Windows-95, Microsoft Office or Adobe PageMaker would take far too many floppies to be practical, so they come on CD-ROM. The floppy disk is the 3½ object you insert into the floppy drive to read it or write on it. The word floppy by itself is ambiguous; it might mean a floppy diskette or a floppy drive. Modern 3½" high density floppy diskettes contain 1.44 MB. The older double density 3½" diskettes are missing the hole in the bottom right corner of the casing and hold half as much data at 720 KB. People in South Africa call the 3½" diskettes "stiffies" since the plastic case is quite rigid. However, the diskettes contain a flexible magnetic cookie inside that spins. The obsolete flexible 5¼" diskettes also came in two sizes, high density AT diskettes at 1.2 MB and double density diskettes with one third the capacity at 360KB. These two are hard to tell apart. The 1.2 MB usually do not have a hub reinforcing ring, while the 360KB do.
function keys
There are a row of keys across the top or down the left hand side of the keyboard. They are labelled F1 F2 .. F10 and sometimes F11 and F12. Unfortunately Microsoft never got around to assigning any standard meaning to these keys. They do different things in different programs. In one, F7 might mean print and another, F7 might mean do a spell check. F1 is usually Help. Alt-F4 (Hold down Alt, then tap F4, then let go of Alt) is usually Close. Ctrl-F6 is usually next document. Programs such as MS Word For Windows get carried away and assign meanings to function key combinations such as: F1, Shift-F1, Ctrl-F1, Alt-F1, Ctrl-Shift-F1 arrgh! These are almost impossible to remember without a template or cheat sheet.
gig
see gigabytes
gigabytes
A gigabyte is 1024 megabytes or 1,073,741,824 bytes (characters). Hard disk capacities are usually 1, 2 or 4 gigabytes. Most disk vendors cheat and state the capacity of their drives in short gigabytes of a billion (1,000,000,000) bytes.
graphics accelerator
First read the definition of a graphics adapter. A graphics accelerator is a just a very fast graphics adapter card. In an ordinary graphics adapter card, the computer must change each pixel individually to change the image on the screen. In constrast, a video adapter takes over much of this work from the computer using high speed specialised circuitry. The computer can say "draw an A" rather than specifying the colours of each dot of the A and its background. Similarly the computer can say "draw a green circle 3 inches in diameter" and the accelerator card will change all the individual pixels inside the perimeter to green. Without the accelerator, the computer would have to individually change each pixel inside the circle. Graphics accelerator cards are now cheap enough that there are almost no situations left where it makes sense to buy a non-accelerated graphics adapter. I can't in good conscience recommend any adapter. The best of a bad lot are a pair of Canadian companies ATI, and Matrox. ATI driver software has always been buggy. Matrox cards are a beast to install. Take your pick.
graphics adapter
The graphics adapter is card that fits in one of the PCI slots in the computer that generates the image that appears on the screen. The image is made of dots called pixels. For example, on a 17" monitor the image might be 1024 dots wide by 768 deep. There are thus 786,432 pixels. People with 21 inch monitors may have an image 1280x1024 pixels. The smallest monitors might support only 640x480 pixels. About 70 times a second, the graphics adapter sends the entire picture, dot by dot, to the screen. For high resolution colour, inside the video graphics adapter, there are three numbers for each dot. One tells how red the dot is, a number from 0 for no red, to 255 for very red, one tells how green it is, and one how blue. 0,0,0 is black. 255,255,255 is white. 255,0,0 is bright red. 0,255,0 is bright green. 0,128,0 is dark green. 0,255,255 is bright yellow. The computer changes the picture by manipulating the numbers associated with each pixel. This scheme gives over 16 million colours. Low res colour might have only one number 0 to 15 associated with each pixel. This works much faster and requires less hidden RAM on the video card, but allows only 16 different colours on the screen at once. A compromise might be 256 or 65,536 different colours. See graphics accelerator, resolution.
gray scale
a monitor that displays only shades of gray.
hard disk
The computers main storage for programs and information. In past PCs used hard disks as small as 5 megabytes; today the smallest manufactured is 2 gigabytes, or 2,048 megabytes. 2 gig is adequate for Windows-95. Little mechanical arms sweep over the rotating magnetic disk surfaces inside the disk. The faster they can move to get to the data you want, the more responsive the disk. The time it takes to traverse 1/3 the distance from outer edge to innermost track is called the average seek time. The smaller this number is, the better. Typical seek times might be 7 milliseconds. The two most common type of hard disks are EIDE and SCSI.
Herc
see Hercules
Hercules
Hercules is a company that made an early popular monochrome graphics card. All such cards, including clones, became known as Herc cards. Hercules now manufactures a line of high end video graphics ards.
IDE
Integrated Drive Electronics. An obsolete, quasi-standard for hard disk controllers. Because of the lack of standardisation, IDE had horrible problems mixing and matching drives even from the same manufacturer. The drive instead of the controller contained most of the smarts. This means the adapter card was very simple, sometimes just an extension to the ISA bus. IDE has been replaced by ATA/EIDE.
IDE is also used in a technical context to mean that the functions formerly performed by the disk adapter card are on the disk drive. So strictly speaking even a SCSI drive is IDE.
ink jet printer
Ink jet printers spray coloured ink onto paper.

The advantages are: The disadvantages are:
Intel
a maker of CPU chips, high quality motherboards, and chip sets (interface chips to help the CPU hook to other parts of the computer).
Internet
a global collection of computers connected by phone lines, satellite links and and fibre optics. You can connect your own personal computer to this network using a modem and a dial up phone line. You have to pay a fee for this privilege to an ISP (Internet Service Provider). From there you can connect to any computer on the net.
IRQ
Interrupt Request. Whenever you install new hardware, improperly assigned IRQs are nearly always the cause of failure.The computer has 16 "shoulders" that i/o devices can tap to get the CPU's attention. For example, every time you hit a key, the keyboard controller taps the CPU on shoulder number 1. This interrupts the CPU from what it was doing, and makes it run a little program to save the keystroke. In general, every device needs its own private shoulder (IRQ), not used by any other device. When you install new hardware, sometimes two devices accidentally get assigned the same IRQ. Under some circumstances IRQ 3 and 4 can be shared by COM2:/COM4: and COM1:/COM3: respectively. Sometimes, especially when you install something like a sound card that needs 3 or more IRQs, there simply are not enough IRQs to go around. You have to remove some device to make room. Cheap 8-bit cards can only use IRQs 0..7. More expensive 16-bit ones can alse use so some of 8..15. Plug & Play devices attempt to assign IRQs automatically. However, 50% of the time it does not work perfectly, and you have to assign them manually, by setting switches and jumpers, by running configuration programs, or by assigning them in the Windows-95 Control Panel / System / Device Manager / Properties / Resources. By clicking on Device Manager / Computer you can see how the various IRQs are currently allotted. Getting these right is tricky and usually requires someone with experience.
IRQ Device Use
0 Timer allows computer to say to iself "interrupt me in 30 milliseconds", a sort of reminder alarm clock.
1 CON: keyboard
2 cascade not available. A kludge used hook the two interrupt controllers together.
3 COM2: or COM4: serial port. Often the modem
4 COM1: or COM3: serial port. Often a mouse
5 LPT2: parallel port for the second printer. Printers can work without any IRQ. IRQ5 is often used by sound cards or bus mice.
6 A: B: floppy disk drives
7 LPT1: parallel port for the printer. Printers can work without any IRQ.
8 real time clock time of day
9 free sometimes used by network Ethernet LAN cards
10 free often used by sound cards
11 free often used by SCSI cards
12 PS/2 mouse Mouse with tiny round connector
13 numeric coprocessor for the chip that does scientific calculations and trigonometry.
14 C: D: EIDE hard disk controller for hard disk, CD-ROM.
15 E: F: Secondary EIDE hard disk controller for extra hard disk, CD-ROM.
ISA
see bus.
ISP
Internet Service Provider. A local company that owns a computer (or computers) with a permanent 24-hour Internet connection. You pay them a monthly fee, usually about $20. You are then allowed to phone their computer up with your computer modem. From there you can connect to any computer in the world on the Internet without a long distance call. Your connection goes through the all-digital Internet satellite or fibre optic links to the computers of your choice. A poor ISP will not install enough dial-up ports on its computer to handle all the customers. You often will get a busy when you dial up. You can test an ISP before you sign up by phoning its number and seeing how often you get a busy. A poor ISP will not have a sufficiently "thick" (technically, high enough bandwidth) pipe to the rest of the Internet to handle all the traffic. Before you sign up, ask other subscribers if their access seems to bog down severely at peak hours. This is a symptom of an inadequate bandwidth. ISPs that offer unlimited access are often a worse buy than ones that limit you to one or two hours a day, because with no incentive to limit use, other subscribers will hog all the lines and never get off to give you a turn.
keyboard
Keyboards come in two main types, clicky/stiff touch and silent/soft touch. You have to try both to see which you prefer. If you don't already touch type QWERTY, you might want to consider learning the modern DSK layout instead. Computers usually come with very low quality keyboards. Spending even $10 extra on the keyboard will greatly enhance your enjoyment. Keys that stick down or keys that don't register when you hit them can drive you nuts. Replacement keyboards cost from $30 to $100 Canadian. If the one you are using offends you, throw it out and get another.
LAN
Local Area Network. LANs let you link computers together so that you can share files, printers or programs. Windows-95 comes bundled with simple LAN software. All you need extra are some Ethernet cards and cabling. Businesses use more complicated and efficient LANs where some computers on the net are designated as servers. Nobody sits at them. The servers do work on behalf of the workstation computers. These business LANs would typically use Novell Netware software. There are other types of LAN besides Ethernet. You may find Arcnet, Lantastic and Token Ring, however Ethernet is by far the most common. See Ethernet.
laptop
Laptop computers are so compact you can carry them around.

The advantages of laptops over desktop computers are: The disadvantages of laptops are:
laser printer
Laser printers work by a Xerographic dry toner process similar to a copier.
The advantages of lasers are: The disadvantages of lasers are:
LCD
Liquid Crystal Display. Laptops use a flat panel screen that works much like the display on a digital watch. The problems with LCD are washout if there is high ambient light, and viewing angle. You have to look at the screen from just the right angle to see the display. Technology is gradually solving these problems, but it still has a way to go to match the brightness of the CRT technology used on desktop computers. Large flat panel displays are still too expensive, though they are now appearing in Japanese wall-mounted TVs. It won't be too much longer till you can panel your desk with them to form a giant wrap-around screen or wear a headset that gives the same effect.
MacIntosh
Apple produces a competing line of computers to the PCs. The older Apples are based around the Motorola 68000 series of CPUs. The newer ones are based around the IBM PowerPC RISC CPU. Windows-95 has borrowed many ideas from the Mac. The MacIntosh market share has been gradually dwindling primarily because of the lack of applications.
mag tape backup
Sooner or later you will turn on your machine and you will discover everything you ever put into it (programs, images, word processing, tax data, your company's books, spreadsheets, your great Canadian novel) is gone. There are several ways this can happen: Usually no amount of wailing, gnashing or teeth, or money will bring it back. You have to start all over from scratch. For many people this would be catastrophic. If you are one of these people, I strongly reccommend getting a mag tape backup unit, and use it to make a copy of your entire hard disk each night, or at least all of your data. Keep at least one backup tape offsite just in case of a fire or theft. Then if your machine fails, you get a new hard disk, and read the tape back onto the hard disk, and you are back in business, losing at most a day's work. Unfortunately the need for mag tape backup units has not yet sunk into the public awareness. They are still almost a specialty item. Units big enough to backup the whole disk can cost over $1,000. This may seem expensive, but on average it would cost about $40,000 to recreate the records in the average computer used for a home business. If you don't use a mag tape, you must back up at least your most crucial data to floppy or ZIP drive. Make sure you do a fire drill to make sure your backup system is working. You would be surprised how many people when it comes time to restore, discover their backup tapes or floppies are empty or are missing crucial data.
MCA
see bus.
meg
see megabytes
megabytes
A megabyte is 1024K or 1,048,576 bytes (characters). Older small hard disk capacities are measured in megabytes. Most disk vendors cheat and state the capacity of their drives in short megabytes of a million (1,000,000) bytes. RAM is always measured in true megabytes.
megahertz
a way of rating the speed of a CPU. Megahertz means millions of cycles per second. A 200 MHz CPU, all else being equal, will calculate twice as fast as a 100 MHz CPU. See CPU.
MFM
Manchester Frequency Modulation or Modified Frequency Modulation. An antique style of hard disk controller.
MHz
see megahertz
MIDI
Musical Instrument Digital Interface. A connector to various MIDI-compatible electronic musical instruments such as keyboard, synthesiser, electronic drum set etc. It allows you to play an instrument and have the computer convert your playing to sheet music, or to automatically play electronic MIDI sheet music, much like a player piano. A sound card usually comes with a built-in MIDI compatible synthesiser. It usually is a crummy sounding FM synthesiser, but on higher end sound cards it can be a full wave table synthesiser that can accurately simulate any combination of acoustic instruments. MIDI is very compact way of storing music. You can pick up a whole song off the Internet in a few seconds and start playing it immediately using the Crescendo add-in software to your web browser. The main limitation of MIDI is that it currently cannot handle the human voice.
MMX
Multi-Media Extension. This is mostly a marketing ploy by Intel, akin to Gleam toothpaste's GL/70 and Chloret's Retsyn. Other chip manufacturers are now also offering MMX. Intel wants you to think MMX is a true digital signal processor, but it is not. Technically, MMX is a SIMD (Single Intruction Stream Multiple Data) auxiliary 64-bit processor integrated with the CPU than can handle 2 identical 32-bit calculations at once, 4 16-bit or 8 8-bit. If your machine has a non-accelerated video card, MMX may help. True dedicated hardware does the job faster and cheaper. MMX is primarily for jazzing up sound and 3D graphics in games. Not much software currently exploits it, but most new computers are being sold with it, so software should soon follow. You might think of it as a solution in search of a problem.
modem
A modem is a device that allows your computer to communicate with other computers over an ordinary phone line. If you listen in on the call, you can hear whistles, honks, and what appears to be white noise static. Most of the time you connect to a computer owned by a local ISP (Internet Service Provider). From there, you can be connected to any other computer in the world currently attached to the Internet.
There are two kinds of modem, internal, which takes the form of an add-in card you insert into a free ISA slot in the motherboard, and external which takes the form of a box with indicator lights that attaches via a cable to your computer's COM2: serial port. Internal modems are cheaper and take up less space. External modems are easier to troubleshoot and reset if they go mad.
Buying a non-name generic modem will waste days in frustration trying to get it to work. Ask your ISP what brand he recommends. You will have most luck if your modems exactly match his. My personal favourite no-nonsense modems are the US Robotics Sportster and Courier.
Modem speeds are measured in BPS, bits per second. Anything less than 28,000 BPS or (28K for short) is obsolete. 33K are most common. There are three kinds of 56K modems, X2, K-Flex and V.90. V.90 is the new standard. X2 and K-Flex were interim experiments and are rapidly on the way out. Very few ISP's support 56K, so you may end up running at 33K even if you buy a 56K modem. Even when your ISP supports 56K, you may end up running somewhat slower unless you have perfectly clean phone lines. For very high speeds, 500K+ you use a cable modem or an ADSL modem. These attach to your machine via an Ethernet LAN connection, and are provided by your ISP. High speed lines are remarkably inexpensive, but are only available in urban areas.
What can you do with a modem?
  1. Directly phone other people who have computers and send them files using a program like Telix. This is so awkward to do, people rarely do it now-a-days. It is much easier to use the Internet email.
  2. Phone local free BBSes (Bulletin Board Systems).
  3. Send your word processing files to people who have FAX machines or who have FAX modems using a program like Faxworks Pro.
  4. Surf the internet looking for information or pornography in the form of text, pictures, movies and sound using a Web browser program such as Netscape.
  5. Download free or shareware programs from computers on the Internet using a web browser or a program like WinFTP.
  6. Send people electronic mail, including electronic enclosures of documents, pictures, MIDI musical scores, or sounds using a program like Eudora or Agent. You can leave email for other computers that only periodically connect via a modem. Each time you connect, you pick up any mail that arrived while you were not connected.
  7. Set up your own pages on the world wide web. Post your art, writing, club notices, photos, advertising etc. for the whole world to come and see, using authoring tools and an uploader program like NetLoad.
  8. Read or participate on global public discussions on every topic you can imagine using a newsreader program like Agent or Galahad.
  9. Meet people from all over the world, and exchange electronic mail.
  10. If you have a FAXmodem, allows you to send and receive faxes.
  11. Contact information services providers such as BIX, Compuserve and AOL. Discussions in these forums is usually more civilised than on the Internet Newsgroups. You don't need to deal with renegades who insist on placing advertisements where they have no relevance.
  12. Most important, you can get free technical help with your computer problems via the newsgroups or vendor web pages. You can pick up free bug fixes and program upgrades. Without a modem, you would never even know they existed.
See ISP, BBS, faxmodem.
monitor
The box that sits on your desktop that display the picture that looks something like a TV. Monitor manufacturers usually lie about the size of the image. You will often find a screen advertised as 15 inches has a picture closer to 13 inches on the diagonal. A 21 inch monitor has twice the display area of a 15 inch monitor. Lots of screen real estate makes it easy to keep many windows at a time open on the screen. Unfortunately 21 inch monitors are considerably more expensive. For serious use, consider at least a 15 or 17 inch monitor.
monochrome
an antique monitor that displays only two colours: black and white, black and green or black and orange.
mouse
A mouse is a puck containing a rolling ball you move around on a flat surface called a mouse pad. A pointer correspondingly moves on the screen. You use it to point at buttons or options on the screen. A mouse has two (Microsoft) or three buttons (Logitech) you can press to initiate some action. Before you buy a mouse, try it out for at 10 minutes or more. Mice are often designed to be comfortable only for left or right-handed people. Also consider the alternative, a track ball which needs less free desk space.
Windows-95 requires you often to double click, i.e. click the left mouse button twice, at exactly the right cadence. It can leave you babbling and drooling trying to get the interval just right. If you click too fast your double click gets treated as a single click. If too slow, it gets treated as two single clicks. With a 3-button mouse, you just press the middle mouse button to simulate a perfect double click. Generally, the older you are, the more trouble you will have with double clicks.
Mice frequently stop working. There is no need to buy a new one. Just open them up, and use a pick to remove the impacted lint. and wash the ball and rollers in isopropyl alcohol. Mice usually wear out after a year or two. It pays to get a good quality mouse such as a Logitech or Microsoft.
There are three kinds of mice:
  1. PS/2: has a small round connector. Does not require a adaptor card, but does require a motherboard with a PS/2 mouse connector. This would be your first choice.
  2. Serial mouse: usually attaches to COM1: connector. You may need an adapter if the mouse and port don't have the same number of pins. Mice usually have 9 pins and COM ports either 9 or 25. Serial mice are not quite as responsive as the other two.
  3. Bus mouse: requires an adapter card installed in a slot. It is often difficuslt to find a free IRQ for this style of mouse. These are the most responive type. They are getting harder to find.
See mouse pad, trackball.
mouse pad
a foam rubber pad that sits on your desk. It provides traction for the mouse's rolling ball. Most desk surfaces are too smooth. Finding room for the pad can be a problem for people like me whose desk is usually covered in books and papers. These cost about $1.50 wholesale. If you buy one retail, you might pay up to $20 for it. Normally a retailer will be happy to throw in a free mouse pad with another purchase, if you ask, especially if it is imprinted with advertising of any sort.
multiread
A CD-ROM, CD-R or CD-RW that can read the erasable CD-ROM discs. Most older CD-ROM drives cannot. All drives can read the non-erasable type, so long as they were written in DAO format. See CD-ROM, CD-R, CD-RW, DAO.
NT
New Technology. Microsoft's serious operating system. It runs most Windows programs. It is not suitable for the average home user. The advantages of NT are: The disadvantages of NT are: See Operating System.
OCR
Optical Character Recognition. A scanner just creates an electronic picture of a page, composed of millions of electronic dots. You can't edit this with a word processor. You need optical character recognition software to analyse the dots, and "see" patterns in them and convert the dots to text. Hewlett Packard bundles WordScan with its scanners. This software is worse than useless. If you fork over several hundred dollars more, you can upgrade to WordScan Plus which is, to be charitable, inadequate. I found Xerox Textbridge cheap (under $100) and much faster and much more accurate. Before you buy a scanner or OCR software, try out the process on someone else's computer. It is incredibly time consuming and just about the most boring thing a human can do. See scanner.
parallel port
The connection on a computer to which you attach a printer. The connector on the computer is a 25-pin D-shaped female connector. The cable has a 25-pin D-shaped male connector on the computer end, and a round, mouth-like Centronics connector for the printer end. A common dirty trick of retailers is to leave out the printer cable, then charge $25 extra for it later. Make sure the cable is included when you buy a computer or a printer. Most computers have only one port, called LPT1: Some have a second one labelled LPT2: and a handful have even a third LPT3:. Printer cables should be as short as possible. Every extra foot means extra headaches and flaky operation. Never go beyond 10 feet unless you have special low capacitance cables. Since Windows-95 does not use the IRQs for its printer support, Windows-95 is fairly forgiving about configuring your parallel ports improperly. However, the following is how they should be set up.
port address IRQ
LPT1: 3BC 7
LPT2: 378 7
LPT3: 278 5
See IRQ, serial port.
PCI
Peripheral Component Interconnect. see bus.
Pentium
an Intel CPU. See CPU.
Pentium II
an Intel CPU. See CPU.
Pentium Pro
an Intel CPU. See CPU.
PIO
Programmed Input Output. A slow form of i/o where the cpu has to spoon feed the peripheral a byte or word at a time. The standard DMA controller is so incredibly slow that, PIO is faster for hard disk access. See DMA.
Plug & Play
Assigning port addresses, IRQs and DMA channels in a way that does not conflict is a black art. Often you don't have full documentation. Every card has a different set of possible choices, and different ways of telling it what to use. Plug & Play is a half-baked attempt to automate this process. The main problem is the legacy cards that don't know the Plug & Play conventions. You have to manually nudge Plug & Play along. The other problem is software that expects long standing conventions to be adhered to. Plug & Play left to itself comes up with some eccentric assignments. Ironically, it can be harder to configure a system that is partly slippery-eel Plug & Play than one with none at all. Happily most Plug & Play devices allow the feature to be turned off, and let you tell the devices which IRQs, address ports and DMA channels to use. Happily Windows-95 now has tools to help in detecting conflicts. Some day, all devices, including the motherboard will be 100% Plug & Play, and the PC will finally evolve to the state the Apple MacIntosh was a decade ago. See IRQ, port address, DMA.
PostScript
PostScript printers have intelligence. The computer can send them a compact computer program mathematically describing the image to produce, then the printer itself composes the tiny dots that form the image, and prints it. In contrast, with most non-Postscript printers, the computer has to compose the dots, then labouriously send the millions upon millions of them over to the printer. If you send the same PostScript computer program to a typesetter, you will get the same results, except with finer detail. With an non-PostScript printer there will be many small differences, including different line endings and page breaks.
power supply
The power supply is a box inside the computer that convents 115 Volts AC to the 5 and 12 volts DC that the electronic components use. The best quality power supplies are PC Power and Cooling Turbo Cools. The extra expense may be worthwhile if:
  1. You have poor quality AC power.
  2. You have several high current devices, such as large disk drives in the machine.
  3. It is crucial that the machine run reliably without hiccoughs.
If have problems with severe sags or power outages, you also need a UPS. See UPS.
PPM
Pages Per Minute. A way of rating the speed of printers. See CPS. Printer.
port
A connection on the computer to which some device is connected such as a printer, modem, mouse.
port address
to come
print cartridge
A pod containing ink or toner. These can be very expensive. Check the costs out of such cartriges and how long they last before you are seduced by what appears to be a low-cost printer.
printer
A device that puts ink on paper. There are five main types:
  1. laser
  2. ink jet
  3. dot matrix
  4. Risograph
  5. colour wax
For details see entries under each type.
RAM
Random Access Memory. The computer's high speed memory. Its contents are lost when you turn off the power or if there is a momentary power failure. This is why every 10 minutes or so you save you work to the hard disk, which retains its information even when the power is off. The more RAM, the more programs you can run at once, and the faster your machine runs. 16 to 32 Megabytes of RAM is adequate for running Windows-95.
RDRAM
RAMBUS Dynamic Random Access Memory is ultra high speed memory. Technically RAMBUS memory can be accessed at 500 MHz effective rate. It does this by using a 250 MHz clock and transferring data on both the rising and falling edge of the clock.
resolution
Resolution is used in several contexts:
See screen, graphics adapter, monitor, printer, scanner, OCR.
Risograph
Risograph printers are for high volume work, when you want 30 to 20,000 copies of each page. They work by melting wax to form a silkscreen master that is then used much like an offset press plate to crank out the copies faster than a page a second. The silk screen masters cost about fifty cents each, so this printer is not suitable when you need less than 30 copies of each page. It can print in various colours of ink. By doing several passes you can get multiple spot colours. The masters come in a roll, so the printer can do a multipage run unattended. After printing, you need to collate the copies. Risograph printers use very little power since no heat is used, and the printing process requires no toxic solvents. The print quality is only about 300 DPI, but not as crisp a laser.
RLL
Run Length Limited. A notoriously unreliable, thankfully antique, style of hard disk controller.
ROM
Read Only Memory. Your computer contains a small permanent uneraseable BIOS program burned into it, stored in ROM chips. This program handles the very basic functions needed to get Windows-95 started. Ordinary RAM loses its contents when you turn off the power. ROM retains its factory-set contents indefinitely.
scanner
A scanner is a device that can look at a page and turn it into an electronic picture, made of millions of dots. Most scanners can see colour, but others see only shades of gray. Most scanners are maddeningly slow, especially if you are trying to scan piles of text. A scanner typically scans at 300 DPI (dots per inch) or 600 DPI. The higher the resolution the more detailed the image. Some low-cost scanner manufacturers advertise bogus high resolutions such as 1200 DPI. They fake this with software that just fills in by averaging a scan done at 300 DPI. The 1200 DPI image actually has no additional detail, it just takes up 16 times as much RAM/disk space. For OCR (Optical Character Recognition) all you need is 300 DPI. With software such as Faxworks Pro, you can use your scanner as a FAX machine to send black and white images to people who have fax machines. You can use a scanner as a sort of colour FAX. You scan an image and enclose it with your Internet email. You can also use the scanner as a very slow copier, by scanning and then printing the image. If you have a colour printer, you can use it like a colour copier. Scanned images take up enormous amounts of room. You can very quickly fill up even the largest hard disk if you keep too many images on file. However, if the images are of printed text, after they have been converted to word processor format with OCR software, they are very compact. See OCR, resolution.
screen
to come
SCSI
Small Computer Systems Interface. SCSI controller cards can handle up to seven devices, usually hard disks, CD-ROMS, back up tape drives or scanners. SCSI hard disks are more expensive than the garden variety EIDE hard disks. SCSI won't buy you any more speed if you use Windows-95. You have to use a true multi-tasking Operating System like OS/2 or NT to get the SCSI speed benefits. There are six flavours of SCSI. Home machines mostly use SCSI-2.
type bits pins async
MHz
sync
MHz
cable
meters
raw
throughput
Mbytes/sec
SCSI 8 50 4 5 6 5
SCSI-2 8 50 8 10 3 10
wide SCSI-2 16 68 8 10 3 20
differential SCSI-2 16 68 8 10 25 20
Fast20 aka Ultra 1 16 68 8 20 3 40
Ultra 2 SCSI 16 68 8 40 12 80
SDRAM
Synchronous Dynamic Random Access Memory is very high speed RAM, up to 150 MHz (7.5 ns). Technically it is synchronous memory that works in sync with the system bus, thereby avoiding wait states. It also has an on-chip burst facility. SDRAM DIMMs are now the prevailing memory architecture, edging out EDO RAM.
serial port
A connector to which you can connect a serial mouse, an external modem or a serial printer (not recommended!). On the computer is a 9 or 25-pin D shaped male connector. There can be up to four COM ports. They must be assigned the following way for all software to work. If they are improperly done, likely some software will work. If there is an internal modem taking up COM2: then there must not be an external COM2: port. Never assign COM1: and COM3: without a COM2:, or any other skip. Unfortunately, there is only about a 1 in 3 chance your retailer will properly configure your COM ports.
port address IRQ
COM1: 3F8 4
COM2: 2F8 3
COM3: 3E8 4
COM4: 2E8 3
SGRAM
Synchronous Graphics Read Only Memory is a fancy type of RAM used to speed up video cards. Technically it is an enhanced version of SDRAM that supports masked writes and block writes, both used primarily to accelerate graphics operations.
SLDRAM
SyncLink Dynamic Random Access Memory. Similar to DirectRDRAM. 400 MHz throughput.
socket
Expensive chips such as the Pentium CPU plug into connectors rather than being soldered in. Intel has recently patented the connectors it uses to block its competitors from fitting their CPUs into Intel-compatible sockets. There are six types of socket of interest:
Type Speed Where used
socket 7 100 MHz Pentium, AMD K6, Cyrix 6x86, Winchip
socket 8 200 MHz Pentium Pro
slot 1 100 MHz Pentium II mainstream
slot 2 100 MHz Pentium II high end
mobile slot 100 MHz Pentium II portables
slot A 100 MHz AMD K7
sound card
to come
speakers
to come
SRAM
to come
static RAM
see SRAM
stiffy
see floppy
super VGA
to come
tag RAM
to come
trackball
A trackball is a ball you spin with your palm or thumb to move the mouse pointer on the screen. These are slightly more expensive than mice. They are less likely than mice to malfunction from impacted lint. For people with a hand tremor, the trackball is easier to use. There are heavy duty versions for small children. Try both a mouse and a trackball before you buy. See mouse.
UPS
Uninterruptible Power Supply). A UPS is a box containing a battery that goes between your computer and the AC wall outlet. If the power fails, it keeps your computer going for 10 minutes on battery backup power. Most power outages are less than 3 seconds long. Ten minutes gives you time to shut down the software gracefully, saving all your work in the event of a long outage. See power supply.
VESA bus
Video Electronics Standards Association bus. This bus was a kludgy attempt to extend the ISA bus. It was replaced by the PCI bus. See bus, PCI, ISA.
VGA
to come
video card
see graphics adapter
VRAM
Video Random Access Memory is used to speed up video cards. Technically it is dual-ported RAM optimized for graphics. It has a special serial output to supply data in a stream mode for graphics updates to refresh the screen.
wait states
to come
wave table
to come
web
to come
Windows-95
to come
WRAM
Windows Random Access Memory is used to speed up video cards. Technically it is yet another version of VRAM that contains special hardware for graphics functions like Blts and fills.
Zip drive
to come

Acknowledgements

Steve Mastrianni of IBM provided the technical information on the various types of RAM. Bruce Stewart and Rj Sypek helped with the acronyms used in the various types of hard disk controllers. Joanne Dow and John Strom also helped.

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