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Midterm Review

Exam: Monday November 16,
During Class time

M. Hamdi
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COMP 381 Midterm Exam Review

. Any computer architect strives to design a
successful computer: A successful com-puter is a cost-effective computer.
Cost: Good price - it is related to die area.
Effectiveness: Good performance
Chapter 1


Cost
. Cost of integrated circuits
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Midterm Exam Review



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COMP 381 Midterm Exam Review

n CPU clock cycles = CPIi ICi i =1
. n .
CPU time = . CPIi ICi. Clock cycle time ..
i =1
n ICi
CPI = CPIi .--------------------------------------------------.

. Instruction count.


i =1
. Amdahls law
The performance improvement to be gained from using some faster mode of execution is limited by the fraction of the time the faster mode can be used.
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COMP 381 Midterm Exam Review

. To quantify Amdahls law, the term speedup has been de.ned as follows: It is the execu-tion time for the entire task without the enhancement over execution time for entire task using the enhancement when possible.
. Fractionenhanced.
ET = .(1 C Fractionenhanced) + ---------------------------------------------------.
new ETold
. Speedu penhanced.
. The overall speedup is de.ned as:
ETold 1
Speedu poverall = -------------------= --------------------------------------------------------------------------------------------------------------------------
ET Fractionenhanced
new
(1 C Fractionenhanced) + --------------------------------------------------
Speedu penhanced
Given two design choices, compare their perfor-
mance using Amdahls Law.
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Midterm Exam Review COMP 381

Midterm Exam Review

.
Encoding an instruction set

.
DLX, and RISC processors in general, favor simplicity - each instruction has the same length.


DLX has 3 types of instructions:


R-type:



I-type:

6 bits 5 bits 5 bits 16 bits

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Chapter 3

Offset added to PC . Pipelining: Pipelining the execution of instruc-26 bits
tions increases the performance and through-

Be familiar with the DLX (integer) architecture and the put of the CPU (A good choice of pipeline reasons behind those architectural choices (register

depth is 4-8 stages).

Change certain architectural features of the DLX, . Pipeline Performance
.
Pipeline Hazards : Their solutions

.
We have gone in detail through the DLX 5-stage pipeline (This part will not be tested)


. DLX has 2 addressing modes: immediate and dis-
Register indirect and absolute addressing are
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Midterm Exam Review COMP 381

Midterm Exam Review


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Midterm Exam Review
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Midterm Exam Review
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Technique Miss ra