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Survey of Program
Compilation and Execution
Bangor High School
Ali Shareef
2/28/06
Main Components of a
Computer
External Devices
Processor
Memory
Memory
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Temporary holding area where instructions
are stored while they are waiting to be
executed.
Data and intermediate values are also
stored in memory.
Memory is Volatile

When the power is shut off, everything in
memory is lost
Processor
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Executes Instruction
Pentium 4 is a 32 bit processor
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Processors can process a 32 digit “bit”
number at a time.
Processor executes instructions one at a
time, (technically).
Instructions are represented as binary
numbers.
Processor

Registers
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Fast memory within the processor where
data is stored while an instruction is being
executed.
Processor
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Pentium 4 processor uses a 2.3 MHz
clock.
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Clock oscillates at 2,300,000 cycles/sec
Most instructions take about 5 cycles
2,300,000/5 ~ 460,000 instructions are
executed per second
Even though a processor is executing one
instruction at a time, user interaction is
very smooth.
Execution Process
1)
2)
Program is loaded into memory from
external storage (hard drive, floppy
disk.)
Processor executes instructions from
memory
Execution
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Can the processor understand C code?
Can it execute C code?
Compilation
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The processor cannot understand most high
level languages such as C.
Need to translate C code to assembly code.
Assembly code corresponds to actual numeric
values for the instructions that the processor
can understand.
A compiler is used to translate code written in
C to assembly code, so that the processor
can understand it.
Demo

Compile program in Visual Studio and
see the assembly code.
Comparison
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Is it better to program in a high level
language like C?
Or assembly code?
Comparison
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Pros : High Level language
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Easy to use,
Easy to debug,
Quickly develop programs
Cons :
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Depend on compiler to produce code
May not be efficient
Comparison
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Pros : Assembly Code
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Can write very efficient, optimal code
Can utilize the full functionalities of the
processor
Cons :
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Hard to write code, hard to debug
Requires knowledge of the architecture of
the processor that you are using
Conclusion
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Main Components of a Computer

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Memory
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Processor, Memory, External devices
Temporary holding area for instructions
Processor
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Executes instructions
Conclusion
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Program Execution
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Load instructions to memory
Processor executes instructions
Compilation

Compiler translates high level language to
assembly
Conclusion

High level language or Assembly use
depends upon application