Goal 1 Textbook Notes Flashcards
Digital computer
A machine that can do work for people by carrying out
instructions given to it.
Program
A sequence of instructions describing how to perform a certain task
Machine Language
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
L1 are executed by the computer, which, after all, can only execute programs written in its machine language,____.
L0
Translation
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.
Interpretation
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.
Interpreter
Program that carries out interpretation
Translation and interpretation are similar. In both methods, the computer carries out instructions in L1 by executing _____ _____ of instructions in L0
equivalent sequences
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
L0
executed
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.
interpretation
Virtual machine (level)
Language is L1 for the machine
People write L2 which can be translated to L1 or executed by an interpreter written in L1
a computer with n levels can be regarded as n different ____ _____, each one with a different machine language.
virtual machines
Level n
Level 3
Level 2
Level 1
Level 0
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
Only programs written
in language L0 can be directly carried out by the ____ _____, without the
need for intervening translation or interpretation.
electronic circuits
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.
lower level
device level
At this level, the designer sees individual transistors, which are the lowest-level primitives for computer designers.
Digital logic level:
gates
built from analog components, such as transistors,
gates can be accurately modeled as digital devices.
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 _____
transistors
registers
register
hold a single binary number up to some maximum
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)
Microarchitecture Level
The registers are connected to the ALU to form a ___ ____, over
which the data flow
data path
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 ______
microprogram
hardware