Document

Machine Language
Alex Ostrovsky
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Introduction
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Hierarchy of computer languages:
1. Application-Specific Language (Matlab
compiler)
2. High-Level Programming language (C++,
Java)
3. Assembly Language (Machine dependent)
4. Machine Language (Machine dependent)
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Introduction (Cont.)
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There is nothing “below” machine
language – only hardware.
Machine Language is the only language
understood by computers (i.e. it’s native
to processor)
Impossible for humans to read. Consists
of only 0’s and 1’s.
• 0001001111110000
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History
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1943 – Colossus
Computer. Based on
the same working
principles as modern
computers.
British mathematician
Max Newman was one
of the main founders of
Colossus.
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History: Colossus - Visual
insight
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Architecture
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Modern computers are using Von
Neumann Architecture (also called
stored-program concept)
It was derived by Von Neumann
(obviously), John Mauchly, and Presper
Eckert.
See picture on a next page for structural design of simple CPU based on Von
Neumann Architecture
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Requirements

Every machine language must contain
following commands:
•
Load instruction (CPU loads data directly from
memory into ac register) consists of:
• Operation code (opcode)
• Address of main memory cell from which ac register will
be loaded
0010000111100011
•
Opcode address
Store instruction stores computed information into a
memory cell or CPU(ALU) register
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Requirements

Normally even the simplest instruction
set includes:
• Arithmetic operations – ADD, SUB (subtract),
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MUL (multiply), DIV (divide), INC (increment),
DEC (decrement)
Logic operations – AND, OR. XOR, NOT
Additional operations like SHIFT, ROTATE
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Assembly Language
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To program in assembly you need to understand
concepts behind machine language and execution-fetch
cycle of CPU.
Assembly is a mnemonic form of machine language.
As noted before, assembly is a machine specific
language.
Although Assembly and machine language might look
similar, they are in fact two different types of languages.
•
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Assembly consists of both binary and simple words
Machine code composed only of 0’s and 1’s
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Assembly language (cont.)
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It is possible to code machine language
directly, thus bypassing assembly instructions.
This is done by replacing Assembly
instructions by machine instruction numbers
directly.
•
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For example:
• Instead of load instruction we might say 0004; thus
load001000110001 is equal to 0004001000110001
• Add might equal to 2005
Execution speed remains the same because
basic instructions (like ADD, SUB, LOAD,
STORE, and etc.) are hardwired into CPU.
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ALU Registers
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Simplest ALU design usually includes:
•
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Program counter register
Accumulator register
Stack pointer register
Memory and ALU exchange information in
words. Word is a fixed chunk of data and
depends on system design. Usually it is
chosen so that one word fits into one memory
slot.
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Execution Process
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Future of Machine Language
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With the introduction of 64-bit CPUs (Itanium, Itanium-2,
AMD 64, new assembly language instructions have to be
added, old ones have to be either redesigned or
eliminated. This also puts stress on compiler designers as
well as hardware implementation.
Most recent introduction of Intel’s family of dual-core
CPUs puts even higher demands on proper hardware and
software implementation.
Possibly current 16 and 32-bit instruction set will become
obsolete in near future in order to avoid backward
compatibility problems and minimize production costs.
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References
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courses.cs.deu.edu.tr/cse122/Machine%20Language.ppt
www.cs.rpi.edu/~hollingd/cpp/lectures/Background.ppt
www.cis.ksu.edu/classes/450/jason/arch_overview.ppt
www.cs.kent.edu/~kschaffe/teaching/f04/chap1.ppt
williams.comp.ncat.edu/COMP375/MachineLanguage.pdf
www.cc.gatech.edu/classes/AY2002/cs2130_spring/cs2130pres02_mo
reintrohistorycintro.ppt
www2.hawaii.edu/~walbritt/ ics312/basicConcepts/lecture.ppt
www.cen.uiuc.edu/~cs101/spr04/lect10.ppt
cs2.cs.brown.edu/lectures/lecture8.pdf
www.andrew.cmu.edu/course/ 45-870/powerpoint/45870wk2-1.ppt
http://www.codesandciphers.org.uk/lorenz/colossus.htm
http://www.coledd.com/electronics/cpu/arch.png
http://www.fact-index.com/m/ma/machine_language.html
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Thank You
Education is what remains after
one has forgotten everything he
learned in school.
A. Einstein
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