Chapter 2 Summary
Bit The smallest unit of data a digital computer can recognize; represented by a 0 or a 1.
Byte A group of 8 bits.
Kilobyte (KB) Approximately 1 thousand bytes (1,024 bytes to be precise).
Megabyte (MB) Approximately 1 million bytes.
Gigabyte (GB) Approximately 1 billion bytes
Terabyte (TB) Approximately 1 trillion bytes.
Petabyte (PB) Approximately 1,000 terabytes.
Exabyte (EB) Approximately 1,000 petabytes.
Zettabyte (ZB) Approximately 1,000 exabytes.
Yottabyte (YB) Approximately 1,000 zettabytes.
Decimal numbering system The numbering system that represents all numbers using 10 symbols
(0–9). EX:
104
103
102
101
100
10000
1000
100
10
1
(4
6
1
8
1)10
=4x10000+6x1000+1x100+8x10+1x1 = 46181
Binary numbering system The numbering system that represents all numbers using just two
symbols (0 and 1).EX:
24
23
22
21
20
16
8
4
2
1
(1
1
0 0 1)2
=1x16+1x8+0x4+0x2+1x1 = 25
ASCII (American Standard Code for Information Interchange)
-
A fixed-length, binary coding system used to represent text-based data for computer
processing on many types of computers.
- can represent up to 256 characters include the characters used in the English alphabet,
as well as some non-English characters, the 10 decimal digits, the other characters usually
found on a keyboard, and many special characters not included on a keyboard such as
Mathematical symbols, graphic symbols, additional punctuation marks, and other symbols
- consisting 1 byte (8 bits) per character
Unicode
-
An international coding system that can be used to represent text-based data in
any written language.
- a universal international coding standard designed to represent text-based data written in
any ancient or modern language, including those with different alphabets, such as Chinese,
Greek, Hebrew, Amharic, Tibetan, and Russian
- consisting of 1 to 4 bytes (8 to 32 bits) per character
Graphics data consists of still images comprised of a grid of small dots, called pixels are colored appropriately to represent an
image
audio data—such as a song or the sound of someone speaking—must be in digital form in order to be stored on a storage
medium or processed by a computer. To convert analog sound to digital sound, several thousand samples—digital
representations
Video data—such as home movies, feature films, video clips, and television shows—is displayed
using a collection of frames; each frame contains a still image
Machine Language Representing Software Programs
Machine language A binary-based language for representing computer programs that the
computer can execute directly.
System unit The main box of a computer that houses the CPU, motherboard, memory, and other
devices.
Motherboard The main circuit board of a computer, located inside the system unit, to which all
computer system components connect.
Central processing unit (CPU) the chip located on the motherboard of a computer that performs
the processing for a computer. Also called the processor
Microprocessor A central processing unit (CPU) for a personal computer.
Multi-core CPU A CPU that contains the processing components or core of more than one
processor in a single CPU.
Dual-core CPU A CPU that contains two separate processing cores.
Quad-core CPU A CPU that contains four separate processing cores.
Word Size
- A computer word is the amount of data (measured in bits or bytes) that a CPU can
manipulate at one time.
- While CPUs just a few years ago used 32-bit words (referred to as 32-bit processors), most
CPUs today are 64-bit processors
Cache Memory
- Cache memory is a special group of very fast memory circuitry located on or close to the
CPU. Cache memory is used to speed up processing by storing the data and instructions that
may be needed next by the CPU in handy locations
- Cache memory today is usually internal cache (built right into the CPU chip). In the past,
some cache memory was external cache (located close to, but not inside, the CPU),
Bus
- A bus is an electronic path over which data can travel.
- each wire in the bus acts as a separate lane, transmitting one bit at a time
Bus Width
- The number of bits being transmitted at one time
- The number of wires in the bus over which data can travel.
Bandwidth
- Throughput or bandwidth; that is, the amount of data that can be transferred via the bus in a
given time period
Random Access Memory (RAM)
- RAM (random access memory), also called main memory, is used to store the essential parts
of the operating system while the computer is running, as well as the programs and data that
the computer is currently using
- RAM is volatile; its content is lost when the computer is shut off.
- In static RAM, a bit of data is stored using the state of a flip-flop. This form of RAM is more
expensive to produce, but is generally faster and requires less power than DRAM and, in
modern computers, is often used as cache memory for the CPU
- DRAM stores a bit of data using a transistor and capacitor pair, which together comprise a
memory cell. The capacitor holds a high or low charge (1 or 0, respectively), As this form of
memory is less expensive to produce than static RAM, it is the predominant form of
computer memory used in modern computers.
- Most desktop and server memory modules today are dual in-line memory modules or DIMMs
notebook computers typically use a smaller type of memory module referred to as a small
outline DIMM or SO-DIMM
- A single in-line memory module (SIMM) has a 32-bit path to the memory chips whereas a
DIMM has 64-bit path
- SDRAM (synchronous dynamic RAM). SDRAM is commonly available in DDR (double-data
rate), DDR2, and DDR3 versions. DDR memory sends data twice as often as ordinary
- DDR RAM is based on the same architecture as SDRAM, but utilizes the clock signal
differently to transfer twice the data in the same amount of time.
- SDRAM to increase throughput, DDR2 transmits twice as much data in the same time period
as DDR, and DDR3 is about twice as fast as the highest-speed DDR2 memory available today.
Each type of SDRAM is typically available in a variety of speeds
Short for Synchronous DRAM, a type of DRAM that can run at much higher clock speeds than
conventional memory
Register High-speed memory built into the CPU that temporarily stores data during processing.
ROM (read-only memory) Nonvolatile chips located on the motherboard into which data or
programs have been permanently stored.
Flash memory Nonvolatile memory chips that can be used for storage by the computer or user;
can be built into a computer or a storage medium.
Expansion slot A location on the motherboard into which expansion cards are inserted.
Expansion card A circuit board that can be inserted into an expansion slot location on a
computer’s motherboard to add additional functionality or to connect a peripheral device to
that computer
ExpressCard module a module that can be inserted into a computer’s ExpressCard slot to add
additional functionality or to connect a peripheral device to that computer; commonly used
with notebook computers.
Bus An electronic path on the motherboard or within the CPU or other computer component
along which data is transferred.
Expansion bus A bus on the motherboard used to connects peripheral devices.
Memory bus The connection between the CPU and RAM.
Frontside bus (FSB) The bus that connects the CPU (via the I/O bridge) to
the rest of the bus architecture.
PCI Express (PCIe) bus (peripheral component interconnect express) One of the buses most
commonly used to connect peripheral devices. Universal Serial Bus (USB) A universal bus used
to connect up to 127 peripheral devices to a computer without requiring the use of additional
expansion cards.
FireWire A high-speed bus standard often used to connect digital video cameras and other
multimedia hardware to a computer.
Port A connector on the exterior of a computer to which a device may be attached.
CPU (Central Processing Unit)
1- Arithmetic/logic unit (ALU) The part of a CPU core that performs logical operations and
integer arithmetic.
2- Floating point unit (FPU) The part of a CPU core that performs decimal arithmetic.
3- Control unit The part of a CPU core that coordinates its operations.
4- Prefetch unit The part of a CPU core that attempts to retrieve data and instructions before
they are needed for processing in order to avoid delays.
5- Decode unit The part of a CPU core that translates instructions into a form that can be
processed by the ALU and FPU.
6- Bus interface unit the part of a CPU core that allows it to communicate with other CPU
components.
System clock The timing mechanism within the computer system that synchronizes the
computer’s operations.
Machine cycle The series of operations involved in the execution of a single machine level
instruction.
1. Fetch—the program instruction is fetched.
2. Decode—the instructions are decoded so the control unit, ALU, and FPU can understand
them.
3. Execute—the instructions are carried out.
4. Store—the original data or the result from the ALU or FPU execution is stored in the CPU’s
registers.
Pipelining The capability of a CPU to begin processing a new instruction as soon as the previous
instruction completes the first stage of the machine cycle.
WITHOUT PIPELINING
Without pipelining, an instruction finishes an entire machine cycle before another instruction
is started.
WITH PIPELINING
With pipelining, a new instruction is started when the preceding instruction moves to the next
stage of the pipeline.
Multiprocessing The capability to use multiple processors or multiple processing cores in a
single computer, usually to process multiple jobs at one time faster than could be performed
with a single processor.
Parallel processing A processing technique that uses multiple processors or multiple processing
cores simultaneously, usually to process a single job as fast as possible.
NanotechnologyThe science of creating tiny computers and components by working at the
individual atomic and molecular levels.
Quantum computing A technology that applies the principles of quantum physics and quantum
mechanics to computers to direct atoms or nuclei to work together as quantum bits (qubits),
which function simultaneously as the computer’s processor and memory.
Optical computer A computer that uses light, such as from laser beams or infrared beams, to
perform digital computations.
Questions
1. A parallel processing processing technique that uses multiple processors or processing cores
simultaneously, usually to process a single job as fast as possible.
2. ASCII A fixed-length, binary coding system used to represent text-based data for computer
processing on many types of computers.
3. Byte A group of 8 bits.
4. Universal Serial Bus (USB) a universal bus used to connect up to 127 peripheral devices to a
computer without requiring the use of additional expansion cards.
5. RAM (random access memory)Chips connected to the motherboard that provide a
temporary location for the computer to hold data and program instructions while they are
needed.
6. Central processing unit (CPU) The chip located on the motherboard of a computer that
performs the processing for a computer.
7. Motherboard The main circuit board of a computer, located inside the system unit, to which
all computer system components connect.
8. Binary numbering system The numbering system that represents all numbers using just two
symbols (0 and 1).
9. Control unit the part of the CPU that coordinates its operations.
10. Nanotechnology The science of creating tiny computers and components by working at the
individual atomic and molecular levels.
1. T a storage medium that can hold 256 GB can hold about 256 billion characters.
2. F The amount of data that can be transferred over a bus in a given time period determines
The bus’s volatility.
3. T Cache memory is typically built into a CPU.
4. T A bus is a pathway, such as on the motherboard or inside the CPU, along which bits
can be transferred.
5. F Computers that process data with light are referred to as quantum computers.
6. The binary number 1101 is equivalent to the decimal number 13.
7. A CPU with four separate processing cores is referred to as a(n) Multi-core CPU.
8. A (n) port is a connector on the exterior of a computer into which a peripheral device
may be plugged.
9. Multi-core CPUs allow multiprocessing, in which the CPU is able to work on multiple jobs at
one time.
A.
B.
C.
D.
E.
F.
KB Kilobyte
RAM Random Access Memory
ROM Read Only Memory
USB Universal Serial Port
PCIe Peripheral Component Interconnect Express
CPU Central Processing Unit
3. Supply the missing words to complete the following statements.
A. The smallest piece of data that can be represented by a computer (a 0 or 1) is called
a(n) bit .
B. UNICODE is an international coding system for text-based data using any written
language.
C. L1 is a type of cache.
D. The part of the CPU that performs logical operations and integer arithmetic is the ALU.