IBM-standard
cables
Reference: Type 1 through Type 9 cable
features and specifications.
IDE (Integrated Drive Electronics)
These drives include the controller components on the drive's circuit board. IDE drives have a 40-pin cable-interface. Usually by cable, they connect to the 16-bit (AT) ISA-bus of the system-boards in some of the newer 286-, 386-, 486- and 586-class computers.
Installation in other computers requires a "host adapter" board, as do IDE drives designed for XT-class systems. (IBM XTs have a 10MegaByte drive; to install a drive with greater capacity, replace the controller and system BIOS). Unlike the ST506 interface, it does not require software drivers but uses a Translation Mode specification. The AT BIOS limited the maximum drive capacity to 528 MB. Newer BIOSes, those programed between 1992 and February 1996, can access drives up to 2.113 GigaByte (GB). Capacities greater than this limit cannot be recognized and could cause the system to freez after powering on. The solution is to update the BIOS. Contact the drive manufacturer. Flash BIOS can be programed to handle the greater capacity; nonflash (nonprogramable) BIOSes must be replaced.
Do not low-level format IDE drives unless the procedure is specifically suggested by the manufacturer&emdash;you could damage the drive.
Note: PC What's The Problem? includes installation, test, and repair suggestions.
IEEE-1394 (or P-1394) or simply
"FireWire"
Developed by Apple and endorsed by Intel and Microsoft, it
is a serial alternative to the parallel SCSI connection. The
original specifications transmitted data at 12.5 MegaBytes
per second (MBps). Subsequent revisions went to 80 MBps.,
then to 100, 200, and currently an isochronous data rate of
400 MBps can be achieved. It has the potential to exceed 1.2
GBps. Each 1394 bus can have up to 63 devices, or nodes
connected by a maximum 72 m of cables with no more than 4.5
m between each device/node. (Bridges can expand this
network.) Virtually any device can be connected (drives,
camcorders, air conditioners, lights, etc.); but there can
be no more than 15 in any path.
This bus automatically initializes itself when it is powered on and whenever a device/node is added or removed&emdash;even with the power on. This is a "hot pluggable," Auto ID (configuration) capability. A half-duplex packet bus, 1394 automatically arbitrates between asynchronous and isochronous (time-dependent) transmissions, setting fair intervals, so that all devices waiting to send data get a chance to do so.
The 1394 cable is made up of six-wires over two twisted-pair wires with a galvanic contact between the pair shields. It uses rugged 10-pin connectors: 6-pins for signals, two pins for power and two for returns. Specifications are available from the IEEE 1394 Trade Association at: http://www.firewire.org Other references: SSI, SSA-Fiber Channel, and Fiber Channel-A. Note:
Note: PC What's The Problem? includes installation and functional troubleshooting suggestions.
Inclinometer
A tool that measures the elevation of an object in degrees. It is used to orientate a satellite dish for optimum satellite signal reception.
Inductor
An electrical component. It is a coiled wire. When an electrical current moves through the wire, a magnetic field is generated around the wire. (Note, the coiled wire temporarily stores energy; when it is disconnected from its power source a spark appears.) Both the building and dissipating magnetic fields resist changes in the flow of electricity; i.e., they show reactance.
An inductor with an adjustable core allows its inductance to be changed plus or minus about 5 to 20 percent from its nominal value. A varying magnetic field is produced when an alternating current (AC ) alternates its direction as it moves through the coiled wire. The frequency with which the AC cycles in changing its direction is measured in Hertz (Hz). A 50-Hz current cycles its direction 50 times a second. The inductor creates an inductive-reactance that acts similar to resistance. The more coiled-turns in the wire, the more its inductance and the greater its reactance.
Inductance is measured in Henrys (H) or smaller: millihenry (mH) or microhenry (µH) ranges.
Reactance (in ohms ) equals the (2 ¹) constant for one cycle, multiplied by the current's frequency (in Hertz), multiplied by the wire's inductance (in Henrys).
All inductors are wound with wire; two functional types are available, coil and choke:
Coil inductors are used to resonate when an electrical current with a specific frequency is applied. Coil inductors are used in high-energy circuits and transformers.
Choke inductors make a circuit react to a range of frequencies. They are used for signal blocking, and in AC filtering and resonant (tuned) circuits.
Note: PC What's The Problem? includes identification, test, repair and replacement suggestions.
Instrument and Communications Cable
These cables are for both internal and external connection of electronic equipment, such as test equipment, data terminals, displays, printers, telecommunications, control and monitoring devices, and similar equipment.
Integrated Circuit (IC) chip
These chips may be composed of microscopic capacitors, diodes, resistors, transistors and logic gates. Visually, you can't tell what is inside a chip, but the number of pins is an indicator of its complexity. A schematic or the chip manufacturer's documentation is required to understand the functions of individual pins, particularly for very-large scale (VLSIC) and application-specific (ASIC) chips.
There are several trends that affect IC packaging: integrating ever more functions inside the chip, reducing the size of the chip, reducing its power consumption, operating at near ambiant terperatures, ease of installation and final proximity to other components on the circuitboard.
Note: PC What's The Problem? includes identification, testand replacement suggestions.
Internal, ( -i )
Label indicates an internal drive with no outer case or powersupply--designed for installation inside a computer's or printing device's case. It interfaces with the "host" either by direct connection via a slot or by separate cables to a controllerboard and powersupply.
IPI (Intelligent Peripheral Interface)
This specification is usually associated with 8- and 14-inch drives used by mainframe computers. Specification includes a 16-bit bus which can be split into dual 8-bit interfaces. Up to eight devices can be connected to one interface, and from two to 16 devices in pairs can be connected using both interface. Cables can be up to 125 meters long. Data transfer rate is 80 megabits per second (Mbps).
IPI-2
Devices with this interface can be daisy chained using single cables to support data transfer rates from 60 to 72 Mbps. It is a device-level interface without intelligent features and error correction.
IPI-3
This is a 32- or 63-pin high-performance parallel interface (HPPI) that transfers multiple blocks of data in one direction at a time using a half-duplex protocol. IPC-3 has no timing requirement. Unlike other HPPI implementations that support full-duplex data transfers, IPI-3 adds a command set to the native HPPI sources and destination sets. The 32-pin IPI-3 interface supports an 800 Mbps data transfer rate; the 62-pin interface supports 1,600 Mbps.
Typically, IPI-3 interfaces use coper twisted-pair (TP) cables of up to 36 meters (approximately 118 feet) long. For distances up to 10 kilometers, it can be adapted to use fiberoptic cables.
IRD
Integrated Receiver Descrambler box controls a satellite dish's movement and selects the channels received
IR
Infrared Radiation
IR
Insulation Resistance
IRD
Integrated Receiver Descrambler box controls a satellite dish's movement and selects the channels received.
IRQ
hardware device such as a keyboard or a drive controller indicating that it needs the CPU's attention. IRQ signals are transmitted along IRQ lines, which connect peripheral devices to an interrupt controller. The interrupt controller prioritizes the incoming interrupt requests from the different devices and delivers them to the CPU.
ISA
Industry Standard Archecture bus was the original IBM PC bus (which was superceeded by the EISA bus). As a label, it indicates that a device is compatible with PC-, XT-, and AT-class systems.
ISDL
ISDN DSL, covered with other DSL service types.
ISDN
Integrated Services Digital Network.
ISOC
Internet Society.
ISO
International Organization for Standardization.
ISO 10149
The international standard which describes the specifications for CD-ROM. Consider: Yellow Book specifications.
ISO 9660
The international standard which describes the file structure for computer files on compact disc. The original version was known as the High Sierra Format.
ISP
In-system Programmable.
IT8
Industry standard colour reference target used to calibrate input and output devices.
ITS
Institute for Telecommunication Sciences.
ITU
International Telecommunications Union.
ITU-R
ITU radio communications unit.
ITU-T
ITU telecommunications unit.
IXC
Interexchange carrier.
References are samples only. Each one is presented in greater detail in the
Technical Research Assistant for 2001
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