Goal 1 Textbook Notes

Question 1

Digital computer

Answer 1

A machine that can do work for people by carrying out
instructions given to it.

Question 2

Program

Answer 2

A sequence of instructions describing how to perform a certain task

Question 3

Machine Language

Answer 3

The people designing a new computer must decide what instructions to include in its machine language. Usually, they try to make the primitive instructions
as simple as possible consistent with the computer’s intended use and performance
requirements, in order to reduce the complexity and cost of the electronics needed.
Because most machine languages are so simple, it is difficult and tedious for people to use them

Question 4

L1 are executed by the computer, which, after all, can only execute programs written in its machine language,____.

Answer 4

L0

Question 5

Translation

Answer 5

One method of executing a program written in L1 is first to replace each instruction in it by an equivalent sequence of instructions in L0. The resulting program consists entirely of L0 instructions. The computer then executes the new L0
program instead of the old L1 program.

Question 6

Interpretation

Answer 6

write a program in L0 that takes programs in L1 as
input data and carries them out by examining each instruction in turn and executing
the equivalent sequence of L0 instructions directly. This technique does not require first generating a new program in L0.

Question 7

Interpreter

Answer 7

Program that carries out interpretation

Question 8

Translation and interpretation are similar. In both methods, the computer carries out instructions in L1 by executing _____ _____ of instructions in L0

Answer 8

equivalent sequences

Question 9

Translation and interpretation are different, in that, in translation, the entire L1 program is first converted to an ___ program, the L1 program is thrown away, and then the new L0 program is loaded into the computer’s memory and ______. During execution, the newly generated L0 program is running and in control of the computer

Answer 9

L0
executed

Question 10

In ______, after each L1 instruction is examined and decoded, it is carried out immediately. No translated program is generated. Here, the interpreter is
in control of the computer. To it, the L1 program is just data. Both methods, and
increasingly, a combination of the two, are widely used.

Answer 10

interpretation

Question 11

Virtual machine (level)

Answer 11

Language is L1 for the machine

People write L2 which can be translated to L1 or executed by an interpreter written in L1

Question 12

a computer with n levels can be regarded as n different ____ _____, each one with a different machine language.

Answer 12

virtual machines

Question 13

Level n

Level 3

Level 2

Level 1

Level 0

Answer 13

Virtual machine Mn, with
machine language Ln

Virtual machine M3, with
machine language L3

Virtual machine M2, with
machine language L2

Virtual machine M1, with
machine language L1

Actual computer M0, with
machine language L0

Question 14

Only programs written
in language L0 can be directly carried out by the ____ _____, without the
need for intervening translation or interpretation.

Answer 14

electronic circuits

Question 15

Programs written in L1, L2, …, Ln must be either interpreted by an interpreter running on a ___ ___ or translated to another language corresponding to a lower level.

Answer 15

lower level

Question 16

device level

Answer 16

At this level, the designer sees individual transistors, which are the lowest-level primitives for computer designers.

Question 17

Digital logic level:
gates

Answer 17

built from analog components, such as transistors,
gates can be accurately modeled as digital devices.

Question 18

Each gate is built up of at most a handful
of ______. A small number of gates can be combined to form a 1-bit memory,
which can store a 0 or a 1. The 1-bit memories can be combined in groups of (for
example) 16, 32, or 64 to form _____

Answer 18

transistors
registers

Question 19

register

Answer 19

hold a single binary number up to some maximum

Question 20

At this level we see a collection of (typically) 8 to 32 registers that form a local memory and a circuit called an
ALU (Arithmetic Logic Unit)

Answer 20

Microarchitecture Level

Question 21

The registers are connected to the ALU to form a ___ ____, over
which the data flow

Answer 21

data path

Question 22

On some machines the operation of the data path is controlled by a program called a _____. On other machines the data path is controlled directly by ______

Answer 22

microprogram
hardware

Question 23

Level 2 AKA

Answer 23

e Instruction Set Architecture level (ISA level).

Question 24

The new facilities added at level 3 are carried out by an interpreter running at
level 2, which, historically, has been called an ___ ___

Answer 24

operating system

Question 25

some of the level 3 instructions are interpreted by the operating system and some are interpreted directly by the microprogram (or hardwired control). This is what we mean by ‘‘hybrid’’ level. Throughout this book we will call this level the ___ ____ ____ _____

Answer 25

Operating system machine level

Question 26

interpreters and translators are written by people called _____ _____ who specialize in designing and implementing new virtual machines.

Answer 26

systems programmers

Question 27

Levels 2 and 3 are always ______. Levels 4, 5, and above are usually, although not always, supported by _______.

Answer 27

interpreted translation

Question 28

Machine languages of Levels 1, 2, & 3 is _____. Level 4 is more readable.

Answer 28

numeric

Question 29

Programs in assembly language are first translated to level 1, 2, or 3 language and then interpreted by the appropriate virtual or actual machine. The program that performs the translation is called an _______

Answer 29

assembler

Question 30

Level 5 usually consists of languages designed to be used by applications programmers with problems to solve. Such languages are often called ______ _____

Answer 30

higher-level languages

Question 31

Programs written in high-level languages are generally translated to level 3 or level 4 by translators known as _____, although occasionally they are interpreted instead. Programs in Java, for example, are usually first translated to an ISA-like language called Java byte code, which is then _______.

Answer 31

compilers interpreted

Question 32

The set of data types, operations, and features of each level is called its _______ * deals with aspects visible to user of certain levels * EX) memory numerical amount shown

Answer 32

Architecture

Question 33

Implementation aspects, such as what kind of technology is used to implement the memory, are not part of the architecture. The study of how to design those parts of a computer system that are visible to the programmers is called ____ _____

Answer 33

Computer architecture

Question 34

electronic circuits, along with the memory and input/output devices, form the computer’s ______

Answer 34

hardware

Question 35

Software

Answer 35

consists of algorithms (detailed instructions telling how to do something) and their computer representations—namely, programs. Programs can be stored on hard disk, CD-ROM, or other media, but the essence of software is the set of instructions that makes up the programs, not the physical media on which they are recorded.

Question 36

Analytical Engine

Answer 36

The analytical engine had four components: the store (memory), the mill (computation unit), the input section (punched-card reader), and the output section (punched and printed output). The store consisted of 1000 words of 50 decimal digits, each used to hold variables and results. The mill could accept operands from the store, then add, subtract, multiply, or divide them, and finally return the result to the store. Like the difference engine, it was entirely mechanical.

Question 37

The von Neumann machine had five basic parts:

Answer 37

the memory, the arithmetic logic unit, the control unit, and the input and output equipment.

Question 38

Together, the arithmetic logic unit and the control unit formed the ‘‘brain’’ of the computer. In modern computers they are combined onto a single chip called the _______

Answer 38

CPU (Central processing Unit)

Question 39

Inside the arithmetic logic unit was a special internal 40-bit register called the _______. A typical instruction added a word of memory to the accumulator or stored the contents of the accumulator in memory.

Answer 39

accumulator

Question 40

bus

Answer 40

a collection of parallel wires used to connect the components of a computer. This architecture was a major departure from the memory-centered IAS machine and has been adopted by nearly all small computers since

Question 41

Moore’s law has created what economists call a ____ _____. Advances in technology (transistors/chip) lead to better products and lower prices. Lower prices lead to new applications.

Answer 41

virtuous circle

Question 42

Cloud computing

Answer 42

mainframe computing V2.0. The idea here is that everyone will have one or more simple devices, including PCs, notebooks, tablets, and smartphones that are essentially user interfaces to the cloud

Question 43

cache memory

Answer 43

used to hold the most commonly used memory words inside or close to the CPU, in order to avoid (slow) accesses to main memory.

Question 44

CPU (Central Processing Unit)

Answer 44

‘‘brain’’ of the computer. Its function is to execute programs stored in the main memory by fetching their instructions, examining them, and then executing them one after another.

Question 45

The components are connected by a _____, which is a collection of parallel wires for transmitting address, data, and control signals. Buses can be external to the CPU, connecting it to memory and I/O devices, but also internal to the CPU, as we will see shortly. Modern computers have multiple buses.

Answer 45

bus

Question 46

CPU: control unit

Answer 46

responsible for fetching instructions from main memory and determining their type.

Question 47

CPU: arithmetic logic unit

Answer 47

performs operations such as addition and Boolean AND needed to carry out the instructions.

Question 48

CPU: high-speed memory

Answer 48

used to store temporary results and certain control information. This memory is made up of a number of registers, each having has a certain size and function. Usually, all the registers have the same size. Each register can hold one number, up to some maximum determined by its size. Registers can be read and written at high speed since they are internal to the CPU.

Question 49

CPU register: Program Counter (PC)

Answer 49

points to the next instruction to be fetched for execution. ( The name ‘‘program counter’’ is somewhat misleading because it has nothing to do with counting anything, but the term is universally used.)

Question 50

CPU register: Instruction Register (IR)

Answer 50

holds the instruction currently being executed.

Question 51

data path

Answer 51

consists of the registers (typically 1 to 32), the ALU (Arithmetic Logic Unit), and several buses connecting the pieces.

Question 52

Register-memory

Answer 52

allow memory words to be fetched into registers, where, for example, they can be used as ALU inputs in subsequent instructions. (‘‘Words’’ are the units of data moved between memory and registers. A word might be an integer.

Question 53

The process of running two operands through the ALU and storing the result

Answer 53

Data path cycle

Question 54

Fetch-decode-execute cycle- CPU executes these instructions in a series of small steps:

Answer 54

1. Fetch the next instruction from memory into the instruction register. 2. Change the program counter to point to the following instruction. 3. Determine the type of instruction just fetched. 4. If the instruction uses a word in memory, determine where it is. 5. Fetch the word, if needed, into a CPU register. 6. Execute the instruction. 7. Go to step 1 to begin executing the following instruction.

Question 55

A program that fetches, examines, and executes the instructions of another program

Answer 55

interpreter

Question 56

A direct hardware (i.e., not interpreted) implementation was used only on the most expensive models. Simple computers with interpreted instructions also some had other benefits. Among the most important were

Answer 56

1. The ability to fix incorrectly implemented instructions in the field, or even make up for design deficiencies in the basic hardware. 2. The opportunity to add new instructions at minimal cost, even after delivery of the machine. 3. Structured design that permitted efficient development, testing, and documenting of complex instructions.