it 252 computer organization and architecture introduction chia-chi teng
TRANSCRIPT
IT 252Computer Organization
and Architecture
Introduction
Chia-Chi Teng
What is computer architecture about?
• Computer architecture is the study of building computer systems.
• IT 252 is roughly split into four parts.– First, we will discusses instruction set architectures—the bridge
between hardware and software.– Second, we introduce more advanced processor
implementations. The focus is on pipelining, which is one of the most important ways to improve performance.
– Next, we talk about memory systems, I/O, and how to connect it all together.
– We will also introduce you to Assembly and C programming through out the course.
Why should you care?
• It is interesting.– You will learn how a processor actually works!
• It will help you be a better programmer.– Understanding how your program is translated to assembly
code lets you reason about correctness and performance.– Demystify the seemingly arbitrary (e.g., bus errors,
segmentation faults)• Many cool jobs require an understanding of computer
architecture.– The cutting edge is often pushing computers to their limits.– Supercomputing, games, portable devices, etc.
• Computer architecture illustrates many fundamental ideas in all computing discipline.– Abstraction, caching, and indirection …
Personnel
Lecturer— Prof. Chia-Chi Teng
—Office hours• MW 10-12• Or by appointment
TA— Michael Zanandrea (Lab)
• [email protected]— Francis Mensah (Lab & Homework)
—TA Office hours• TBD
Course webpage: http://it252.groups.et.byu.net/12wi/IT252.php
Administrivia
• The textbooks provides the most comprehensive coverage– "Computer Systems: A Programmer's Perspective" 2nd Edition,
by Randal E. Bryant & David R. O'Hallaron– The C Programming Language, Kernighan & Ritchie, 2nd ed.
• Read the text prior to class• class will supplement rather than regurgitate the
text• IT curriculum changes in Fall 2010
• IT 251 (4) -> IT 252 (3)• IT 104B (2) -> CS/ECEn 124 (3)• IT 104A (2) -> part of IT 327 (4)
• Did you take 104 or 124?
Grading
• Professionalism: Attendance, Attitude, Participation, 5% final grade
• Homework – Usually due on every Friday and Monday, check course website often for detail and update, 25% final grade
• Quizzes - about 6 – 8, take home, 10 pts each, 15% final grade
• Lab reports – Due date to be specified by TA, 25% final grade
• Exams - final and at least one mid-term; usually open-book, take home, untimed 30%
Homework
• Homework exercises provide added impetus to keep up with the reading.
• Textbook problems • Assignments are listed on course web page by weeks,
usually due on Monday of the following week.
• Turn in: on blackboard AND in paper.
• Homework locker.• We really want to encourage discussion, both in class and
in lab.• But zero tolerance for cheating, don’t go there. Don’t look
for solutions online.
• HW1 due two weeks from today on 9/12, due to Labor day. Start early.
Labs
No lab this week. Lab 1 next week. Room 335
—Hardware Description Language (VHDL), CPU design Room 365
—Memory system, I/O … Lab report: TA will give you detail
To-Do list
• Read chapter 1 before Thursday• please read the entire course web thoroughly, today
• Course web is work in progress, please check back often
• IT 252 blackboard• check your email daily• keep up with the reading: this week …• homework due
– Check website (again, turn in on Blackboard & on paper)• lab report due
– TA discretion via blackboard
What is Computer Architecture?It’s the study of the ___________ of computers Structure: static arrangement of the parts Organization: dynamic interaction of the parts and their
control Implementation: design of specific building blocks Performance: behavioral study of the system or of some
of its components
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Another definition: Instruction Set Architecture (ISA)
• Architecture is an interface between layers• ISA is the interface between hardware and software• ISA is what is visible to the programmer (and ISA might be
different for OS and applications)• ISA consists of:
– instructions (operations and how they are encoded)– information units (size, how they are addressed etc.)– registers (or more generally processor state)– input-output control
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Computer structure: Von Neumann model
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Memory hierarchy
I/Ocontrol ALU
RegistersPC
state
Memory busI/O bus
CPUData path +
Control
1945
Computer Organization• Organization and architecture often used as synonyms• Organization (in this course) refers to:
– what are the basic blocks of a computer system, more specifically
• basic blocks of the CPU• basic blocks of the memory hierarchy
– how are the basic blocks designed, controlled, connected?
• Organization used to be transparent to the ISA.• Today more and more of the ISA is “exposed” to the
user/compiler.
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Moore’s Law
• In 1965, Gordon Moore predicted that the number of transistors that can be integrated on a die would double every 18 to 24 months (i.e., grow exponentially with time).
• Amazingly visionary – million transistor/chip barrier was crossed in the 1980’s.– 2300 transistors, 1 MHz clock (Intel 4004) - 1971– 16 Million transistors (Ultra Sparc III)– 42 Million transistors, 2 GHz clock (Intel Xeon) – 2001– 55 Million transistors, 3 GHz, 130nm technology,
250mm2 die (Intel Pentium 4) - 2004– 140 Million transistors (HP PA-8500)– Today: 2.6 Billion transistors (10-core Xeon)– http://en.wikipedia.org/wiki/Transistor_count
Illustration of Moore’s Law
Power Dissipation
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Evolution of Intel Microprocessor Speeds
0
500
1000
1500
2000
2500
3000
3500
4000
1971 1974 1979 1982 1985 1989 1993 1997 1998 1999 2000 2001 2002 2003
Year
Sp
eed
(M
Hz)
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How about today?
POLL
Which type of CPU has the largest worldwide market share?—Intel—AMD—ARM—MIPS
http://www.polleverywhere.com/multiple_choice_polls/LTE2OTY2MjI
Where is the Market?
290
933
488
1143
892
135
4
862
1294
1122
1315
0
200
400
600
800
1000
1200
1998 1999 2000 2001 2002
Embedded
Desktop
Servers
Mill
ions
of C
ompu
ters
ISA Type Sales
0
200
400
600
800
1000
1200
1400
1998 1999 2000 2001 2002
Other
SPARC
Hitachi SH
PowerPC
Motorola 68K
MIPS
IA-32
ARM
What’s in your cell phone?
Mill
ions
of P
roce
ssor
Processor Performance Increase
1
10
100
1000
10000
1987 1989 1991 1993 1995 1997 1999 2001 2003
Year
Per
form
ance
(S
PE
C I
nt)
SUN-4/260 MIPS M/120MIPS M2000
IBM RS6000
HP 9000/750
DEC AXP/500 IBM POWER 100
DEC Alpha 4/266DEC Alpha 5/500
DEC Alpha 21264/600
DEC Alpha 5/300
DEC Alpha 21264A/667Intel Xeon/2000
Intel Pentium 4/3000
DRAM Capacity Growth
10
100
1000
10000
100000
1000000
1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
Year of introduction
Kb
it c
apac
ity
16K
64K
256K
1M
4M
16M
64M128M
256M512M
Impacts of Advancing Technology
• Processor– logic capacity: increases about 30% per year– performance: 2x every 1.5 years
• Memory– DRAM capacity:4x every 3 years, now 2x every 2 years– memory speed:1.5x every 10 years– cost per bit: decreases about 25% per year
• Disk– capacity: increases about 60% per year
ClockCycle = 1/ClockRate
500 MHz ClockRate = 2 nsec ClockCycle1 GHz ClockRate = 1 nsec ClockCycle4 GHz ClockRate = 250 psec ClockCycle
Example Machine Organization
• Typical workstation design target– 25% of cost on processor– 25% of cost on memory (minimum memory size)– Rest on I/O devices, power supplies, box
CPU
Computer
Control
Datapath
Memory Devices
Input
Output
PC Motherboard Closeup
Inside the Pentium 4 Processor Chip
Some Computer families• Computers that have the same (or very similar) ISA
– Compatibility of software between various implementations• IBM
– 704, 709, 70xx etc.. From 1955 till 1965– 360, 370, 43xx, 33xx From 1965 to the present– Power PC
• DEC– PDP-11, VAX From 1970 till 1985– Alpha (now Compaq, now HP) in 1990’s
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More computer families• Intel
– Early micros 40xx in early 70’s– x86 (086,…,486, Pentium, Pentium Pro, Pentium 3, Pentium 4)
from 1980 on– IA-64 (Itanium) in 2001
• SUN– Sparc, Ultra Sparc 1985 0n
• MIPS-SGI– Mips 2000, 3000, 4400, 10000 from 1985 on
– CISC vs RISC– Complex Instruction Set vs Reduced Instruction Set– What is an instruction?
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Where Are We Now?
CS142 & 124
IT344
Registers• Registers are the “bricks” of the CPU• Registers are an essential part of the ISA
– Visible to the hardware and to the programmer• Registers are
– Used for high speed storage for operands. For example, if variables i,j are in registers ax,cx respectivelyadd ax,cx # i = i + j
– Easy to name (most computers have limited number of registers visible to the programmer)
– Used for addressing memory
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Registers (ct’d)• Not all registers are “equal”
– Some are special-purpose (e.g. program counter, stack pointer)
– Some are used for integer and some for floating-point– Some have restricted use by convention
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Memory system Memory is a hierarchy of devices with faster and more
expensive ones closer to CPU—Registers—Caches (hierarchy: on-chip, off-chip)—Main memory (DRAM)—Secondary memory (disks)
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Information units Basic unit is the bit (has value 0 or 1) Bits are grouped together in units and operated on
together:—Byte = 8 bits—Word = 2 or 4 bytes—Double word = 2 words—Etc.
Integer: usually 4 bytes
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Memory addressing
• Memory is an array of information units– Each unit has the same size– Each unit has its own address– Address of an unit and contents of the unit at that
address are different
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address
012
-123170
contents
Addressing• In most of today’s computers, the basic unit that can be
addressed is a byte. (how many bit is a byte?)– MIPS (and pretty much all CPU today) is byte addressable
• The address space is the set of all memory units that a program can reference– The address space is usually tied to the length of the registers– Intel 384/486/Pentium has 32-bit registers. Hence its basic
address space is 4G bytes– MIPS has 32-bit registers. – Older micros (minis) had 16-bit registers, hence 64 KB address
space (too small)– Some current (Intel CoreX, Alpha, Itanium, Sparc, Altheon)
machines have 64-bit registers, hence an enormous address space
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Addressing words Although machines are byte-addressable, 4 byte integers are the
most commonly used units Every 32-bit word starts at an address divisible by 4
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int at address 0
int at address 4
int at address 8
Big-endian vs. little-endian Byte order within an int:
RS-232 Ethernet Frame
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0
0
123
1 2 3
Little-endian (we’ll use this)
Big-endian
012
Memory address
3
int #0byte
int #0
The CPU - Instruction Execution Cycle
The CPU executes a program by repeatedly following this cycle1. Fetch the next instruction, say instruction i2. Execute instruction i3. Compute address of the next instruction, say j4. Go back to step 1
Of course we’ll optimize this but it’s the basic concept
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What’s in an instruction?• An instruction tells the CPU
– the operation to be performed via the OPCODE– where to find the operands (source and destination)
• For a given instruction, the ISA specifies– what the OPCODE means (semantics)– how many operands are required and their types, sizes etc.
(syntax)• Operand is either
– register (integer, floating-point, PC)– a memory address– a constant
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