algorithm A mathematical formula or routine for solving a problem. An algorithm usually is a series of steps defining the most efficient way to get something done.
AUTOEXEC.BAT This is the second of DOS's startup files that you can modify. AUTOEXEC.BAT is a text file on disk that you can edit using a text editor such as ED. In AUTOEXEC.BAT, you place commands that configure the way DOS looks and behaves, as well as load startup programs.
BBS An acronym for Bulletin Board System. A BBS is a computer hooked into a phone line that waits for other computers to call it. When another computer does call, the BBS answers the phone and runs a special program for the calling computer.
Bernoulli drive A type of removable disk drive, somewhere between a floppy disk and a hard drive. Bernoulli drives operate off of aerodynamic principles discovered by the Swiss mathematician Daniel Bernoulli. A Bernoulli drive reads Bernoulli disks, which essentially are large capacity, high speed floppy disks.
bits The smallest unit of storage in a PC. A bit is a tiny switch that can be either on or off, thereby storing a value of either one or zero. The word bit actually is a contraction of binary digit, because ones and zeros make up the binary counting system.
boot disk The disk with which you start your PC. A boot disk has special files on it that the computer initially reads. Those files then take care of starting the computer and loading the disk operating system, DOS. On a PC, a boot disk can either be a floppy disk in drive A, or the hard drive C.
byte(s) The basic unit of information storage in a PC. A byte technically is a collection of eight bits. However, it helps to think of one byte as the amount of storage space required to hold one character. The word byte requires four bytes of storage space in a computer; one byte for each character. A kilobyte (1K) is 1024 bytes, and a megabyte (1Mb) is 1024K. A megabyte contains 1,048,576 bytes.
CPU An acronym for central processing unit. The CPU is your computer's microprocessor. (See microprocessor.)
cache (See disk cache.)
capacity Refers to how much something can hold. The capacity of a disk is measured in megabytes, although the capacity of some floppies is measured in kilobytes.
cluster(s) A storage unit for files on disk. DOS creates clusters from one or more sectors on a disk. Files are stored by the cluster. (See sector, File Allocation Table.)
compression Compression is how Stacker stores more files on disk. Files are compressed using special algorithms that can reduce the amount space a file occupies without subtracting from the file's content. Stacker compresses files as they're written to the Stacker drive. Files are decompressed when they're read from the Stacker drive. (See algorithm, decompression.)
compression ratio The difference between a file's actual size and the amount of space it occupies on a Stacker drive. Stacker strives to store files at a 2:1 compression ratio, meaning that a file will shrink to half size when stored on a Stacker drive. A compression ratio of 4:1 means the file is stored at one quarter size; a compression ratio of 1:1 means the file is stored at full size, which is lousy compression.
CONFIG.SYS This is the first of DOS's startup files that you can modify. CONFIG.SYS is a text file on disk you can edit using a text editor, such as ED. Commands in CONFIG.SYS configure your system and load special control programs called device drivers. Stacker is such a device driver. (See device drivers.)
console (See system unit.)
controller (See disk controller.)
cylinder(s) Two or more tracks on a disk are referred to as a cylinder. Because each side of a disk--including the multiple sides of a hard drive--contain the same track numbering scheme, the tracks are collectively referred to as cylinders. (See tracks.)
decompression The reverse of compression; restoring files to their original size and integrity. When files are copied off a Stacker drive, they're decompressed.
defragment To rebuild files on a disk, usually done by a disk optimization utility. Files are defragmented by the utility, which picks up the various pieces of a file and puts them back in contiguous order. (See fragmentation.)
density Refers indirectly to the capacity of a floppy diskette. Specifically, a disk's density is the number of tracks per inch. In the old days, this value, either double-density or single-density, referred to the capacity of a disk. Today the term density has been tossed aside; diskettes are referred to by their overall capacity. (See capacity.)
device driver A special program that controls a device in your computer. For example, device drivers exist to control memory, a mouse, a CD-ROM drive, external drives, etc. The Stacker device driver controls the Stacker drive. Device drivers are loaded in the CONFIG.SYS file using the DEVICE command.
directory entry When DOS creates a file on disk, it notes information about the file in the directory entry. Information stored in the directory entry includes the file's name, its size in bytes, date and time, plus the file's actual location on the disk.
disk cache A special type of program that uses memory to speed up disk operations. A disk cache is controlled by a program, such as SMARTDrive. It saves information read from disk and monitors all disk access. If the same information is read from disk more than once, the cache program reads it instead from memory. Because most information is read from disk repeatedly, this speeds up disk operations.
disk controller The electronic doohickey that controls the disk drives and allows your computer to communicate with them. Most disk controllers are expansion cards that plug into your computer's motherboard. There are five popular types of disk controllers: IDE, ESDI, SCSI, MFM and RLL. (See expansion card.)
disk optimizer A program that marches through all the files on your disk and defragments them. (See fragmentation.)
download To copy files or information from a remote computer to your own. When you dial a BBS using your modem, you download software from that system to your own. You also can download files from a network server. (See BBS.)
drive A device in the computer that holds a disk. The drive reads and writes information from and to the disk. Drive is short for disk drive.
drive letter DOS assigns each drive in your system a letter, starting with A for the first floppy drive. The first hard drive is letter C, followed by any additional hard drives, RAM drives, Stacker drives, etc. The highest drive letter is Z.
drive letter swapping To maintain compatibility with files set up to run on a certain drive, Stacker will swap drive letters between a Stacker drive and the host drive. Drive letter swapping is handled by the SSWAP program and can be viewed by the SWAPMAP utility.
expansion card A circuitry board that you plug into your computer. An expansion card plugs into an expansion slot on your computer's motherboard. The expansion card then gives your PC extra features and abilities. The Stacker co-processor hardware comes on an expansion card.
expansion slots These are a several long slots near the back of your computer's motherboard. Expansion cards are plugged into the expansion slots. These allow you to expand the abilities of your computer by adding more options.
FAT (See File Allocation Table.)
File Allocation Table (FAT) A map of a disk's storage space. DOS creates the FAT, which maps out all the clusters on a disk into which DOS can store files. The FAT tells which clusters are used, which are available, and which have been marked unusable or bad by the FORMAT program when it created the disk. A link between a file's directory entry and the FAT is how DOS tells where a file is located on the disk. (See clusters, directory entry.)
file name The name given a file. Under DOS, a file name can be from one to eight characters long, followed by an optional period (or dot) and from one to three additional characters. The first part of the file name is called the filename; the second part is the extension. DOS allows a variety of characters to be used in a file name, although for brevity's sake, assume that only numbers and letters of the alphabet can be used.
floppy disk/floppy drive The floppy drive is a device that ``eats'' floppy disks. A floppy disk is a removable type of disk storage in your PC. For the computer to access information on the floppy disk, you must insert it into a floppy drive. Under DOS, two floppy drives are available: A and B.
format The process of preparing a disk for use under DOS, carried out by the FORMAT command. When DOS formats a disk, it creates a series of tracks, which are divided up into sectors. Files are stored on those tracks and sectors, similar to the way people sit at tables and chairs in a restaurant.
fragmentation The process of splitting up large files into available space on a disk. Fragmentation allows large files to be stored when no large spaces exist. When that occurs, DOS splits the file up into fragments, storing them in available space. The FAT keeps track of the pieces, so DOS can assemble the file contiguously when you need it. However, over a period of time, too many fragmented files slows disk access. When that occurs, you need to run a disk optimizer to defragment your drive.
hard drive The physical device that contains your hard disk and the mechanics that spin it around and access information on the disk. Unlike the floppy drive, a hard drive contains both the mechanics as well as the disk itself.
host drive Under Stacker, the host drive is the original hard drive or the drive that contains the STACVOL.DSK file. The Stacker device driver converts the STACVOL.DSK file into the Stacker drive. In some cases, the host drive letter is swapped with the Stacker drive letter.
logical drive A logical drive is a disk drive in your system. One that's assigned a drive letter, but which might not have a physical counterpart. For example, a single hard drive can be partitioned into several logical drives; your first physical hard drive might contain logical drives C, D, and E. If you have only one floppy drive, then it can be either logical drive A or logical drive B.
memory management The art (as opposed to science) of controlling memory in a PC. DOS has only a limited amount of memory available--640K. To make the most of that, special memory management software is available. The main purpose of this software is to load device drivers and TSRs high, thereby leaving more of the 640K available to other programs. (See device drivers, TSRs.)
memory-resident program (See TSRs.)
microchannel This is the name IBM gave to its new expansion slot system on the PS/2 line of computers. Presently only IBM computers and a few clones use the Microchannel architecture or MCA. Stacker's MC/16 co-processor hardware is designed for such a system. (The other expansion slot system is referred to as the ISA system.)
microprocessor This is your computer's brain, the main chip which is responsible for all activity inside the PC. Microprocessors in a PC are referred to by their numbers: 8088, 8086, 80286, 386, etc.
modem A contraction of modulator-demodulator. A modem is a device that translates electronic signals from a computer into sounds that can be sent over ordinary phone lines. A modem on the receiving end translates the sounds back into electronic signals -- bits and bytes -- for the other computer.
motherboard This is the main piece of circuitry inside a computer. On the motherboard, you'll find memory chips, the microprocessor, special control chips or BIOS chips, plus the expansion slots. Everything in the computer plugs into the motherboard, which then connects it with the computer's brain, the microprocessor. (See microprocessor.)
mount This is the act of adding a Stacker drive to your system. Usually applied to removable drives, such as Stacker floppies, you mount a disk using the STACKER program. Only after mounting the disk can it be accessed.
partition A partition is a separate logical drive on a single physical drive. For example, your first physical drive might be logically partitioned into drives C and D. This was required in the olden days, back when DOS could handle only a 32Mb hard drive. You still can partition a drive today, dividing it up into smaller logical drives, although after DOS 4.0 this isn't necessary. (See logical drive.)
physical drive The physical disk drive; the device itself as opposed to the drive letter assigned to it. If you have only one floppy drive, then it's the physical drive A. If you access drive B, then physical drive A becomes logical drive B. On a hard drive, the first physical drive can be partitioned into one or more logical drives, each independent of the others and with its own drive letter.
platter The technical term used to define the number of disks in a hard drive. A floppy drive has only one disk, but hard drives can have many. Because the whole unit is called a hard disk, the individual disks within the drive are referred to as platters.
RAM drive (also RAM disk) This is a special disk drive created from memory, usually by a device driver such as RAMDrive, which is included with DOS. A RAM drive is much faster than any mechanical disk drive. They're limited, however, by two important factors: RAM drives require memory, which usually is at a premium. Also, RAM drives are volatile; when you turn off the power or reset, the contents of the RAM drive are erased.
reboot Also known as reset, restart or a warm boot, this is the act of resetting your computer. A reboot is similar to turning the power switch on and off again; it allows you to start over without completely turning the computer off. On a PC, you can reboot by pressing the Ctrl, Alt, and Del keys at the same time. If your PC has a reset button, you can push it instead.
sector(s) Sectors are sections of the tracks DOS creates when a disk is formatted. Each sector typically contains 512 bytes. The number of sectors per track depends on the overall size of the disk.
stack The act of creating a Stacker drive or, more specifically, creating a Stacker drive out of an existing drive on your system. For example, if you were to stack drive C, the INSTALL program would create a Stacker drive and then copy all the files from drive C to that Stacker drive. Through additional wizardry, the Stacker drive then would become your C drive.
stacked The way to refer to a drive after it has been made into a Stacker drive; the past tense of stack.
stacked volume (See Stacker drive.)
Stacker drive A drive on your system created by Stacker, specifically the STACKER.COM device driver in CONFIG.SYS. A Stacker drive can be an empty drive you create or an existing drive on your system. You use a Stacker drive just as you would any other drive in your system.
STACVOL.xxx file This is a special, hidden file on disk. Stacker uses the STACVOL file to create the Stacker drive. The STACVOL file is the Stacker drive. The extension, xxx, is normally DSK, although empty Stacker drives can have the extension 000, 001, etc. This file should never be deleted or altered.
system unit This term refers to the basic computer box, which contains the PC's motherboard, expansion cards, disk drives, power supply, and so on.Another term for system unit is console.
text editor Like a mini-word processor, a text editor is a special program that creates and edits text-only, or ASCII, files on disk. Stacker's text editor is called ED. You can use it to create or edit any text file, including CONFIG.SYS and AUTOEXEC.BAT.
track(s) These are concentric circles of information DOS creates on a disk as it's formatted. Tracks are divided into sectors. It's in those sectors that program information (bytes) will be held. When tracks appear on both sides of a floppy disk, or multiple sides of a hard drive, they're referred to as cylinders.
TSR This is a horrid acronym for any program that stays in memory after it's done executing. TSR stands for terminate and stay resident. It's a programmer's routine inside DOS that allows programs to remain hidden in memory and carry out special tasks. STACKER is a TSR that monitors activity on your Stacker drives.
uncompressed drive This refers to the host drive or, if an empty Stacker drive was created, to the part of the disk not used by the STACVOL file. Files stored on the uncompressed drive will not benefit from Stacker's improved disk storage abilities. (See compression.)
un-mount This is the process of deactivating a Stacker drive. To access a Stacker drive, it must first be mounted. To discontinue access, the Stacker drive must be un-mounted. Stacker floppies are un-mounted when you switch disks in the drive. Also, any Stacker drive can be un-mounted using the STACKER program.
utility/utilities Special types of computer programs that carry out maintenance chores or other repetitive tasks. Stacker comes with several utilities, plus the integrated utility package, STAC.
volume A fancy term for a disk. Some manuals might refer to the Stacker drive as the Stacker volume. DOS refers to a disk as a volume in the DIR command or with the VOL and LABEL commands.
volume partition A fancy term for a logical hard drive. (See partition, logical drive.)