1. Chapter 1 Computer Abstractions and Technology
Slides partially adapted from Computer Organization and Design,3rd Edition,
Patterson & Hennessy, © 2005 Elsevier, Inc.

2. Introduction This course is all about how computers work
But what do we mean by a computer?
Different types:
desktop, servers, embedded devices
Different uses:
automobiles, graphics, finance, genomics…
Different manufacturers:
Intel, Apple, IBM, Microsoft, Sun…
Different underlying technologies and different costs!

3. Introduction Analogy: Consider a course on “automotive vehicles”
Many similarities from vehicle to vehicle
e.g., wheels
Huge differences from vehicle to vehicle
e.g., gas vs. electric
Best way to learn:
Focus on a specific instance and learn how it works
While learning general principles and historical perspectives

4. Why learn this stuff? You want to call yourself a “computer scientist”
You want to build software people use
need performance
You need to make a purchasing decision or offer “expert” advice

5. The Computer Market
Millions of Computers

6. Why learn this stuff? Both Hardware and Software affect performance:
Algorithm determines number of source-level statements
Language/Compiler/Architecture determine machine instructions (Chapter 2 and 3)
Processor/Memory determine how fast instructions are executed (Chapter 5, 6, and 7)
Assessing and Understanding Performance in Chapter 4

7. “By the architecture of a system, I mean the complete and detailed specification of the user interface.
...
As Blaauw has said,
‘Where architecture tells what happens, implementation tells how it is made to happen.’”
The Mythical Man-Month,
Frederick P. Brooks, Jr.

8. What is a computer? Components: input (mouse, keyboard)
output (display, printer)
memory (disk drives, DRAM, SRAM, CD)
network
Our primary focus: the processor (datapath and control)
implemented using millions of transistors
Impossible to understand by looking at each transistor
We need...

9. Abstraction Delving into the depths reveals more information
An abstraction omits unneeded detail, helps us cope with complexity
Example:
High-level Language
Assembly Language
Machine Language
What are some of the details that appear in these familiar abstractions?

10. Instruction Set Architecture (ISA)
ISA: An abstract interface between the hardware and the lowest level software of a machine that encompasses all the information necessary to write a machine language program that will run correctly, including instructions, registers, memory access, I/O, and so on.
Enables implementations of varying cost and performance to run identical software
ABI (application binary interface): The user portion of the instruction set plus the operating system interfaces used by application programmers. Defines a standard for binary portability across computers.

11. ISA Type Sales
Millions of Processor
PowerPoint “comic” bar chart with approximate values (see text for correct values)

12. 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

13. 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.
1971: 2300 transistors, 1 MHz clock (Intel 4004)
16 Million transistors (Ultra Sparc III)
2001: 42 Million transistors, 2 GHz clock (Intel Xeon)
2004: 55 Million transistors, 3 GHz, 130nm technology, 250mm2 die (Intel Pentium 4)
140 Million transistor (HP PA-8500)

14. Processor Performance Increase
Intel Pentium 4/3000
DEC Alpha 21264A/667
DEC Alpha 21264/600
Intel Xeon/2000
DEC Alpha 5/500
DEC Alpha 4/266
DEC Alpha 5/300
DEC AXP/500
IBM POWER 100
HP 9000/750
IBM RS6000
MIPS M2000
SUN-4/260
MIPS M/120

15. DRAM Capacity Growth
512M
256M
128M
64M
16M 4M 1M
256K
64K
16K

16. Example Machine Organization
Workstation design target
25% of cost on processor
25% of cost on memory (minimum memory size)
Rest on I/O devices, power supplies, box
Computer
CPU
Memory
Devices
Control
Input
Datapath
Output

17. PC Motherboard Closeup

18. Inside the Pentium 4 Processor Chip

19. Example Machine Organization TI SuperSPARCtm TMS390Z50 in Sun SPARCstation20
MBus Module
SuperSPARC
Floating-point Unit
DRAM
Controller L2 CC
Integer Unit
MBus
L64852
MBus control
M-S Adapter
Inst
Cache
Ref
MMU
Data
Cache
STDIO
SBus
serial
SCSI
kbd
Store
Buffer
SBus
DMA
mouse
Ethernet
audio
RTC
Bus Interface
SBus
Cards
Boot PROM
Floppy

20. How do computers work? Need to understand abstractions such as:
Applications software
Systems software
Assembly Language
Machine Language
Architectural Issues:
i.e., Caches, Virtual Memory, Pipelining
Sequential logic, finite state machines
Combinational logic, arithmetic circuits
Boolean logic, 1s and 0s
Transistors used to build logic gates (CMOS)
Semiconductors/Silicon used to build transistors
Properties of atoms, electrons, and quantum dynamics

21. Instruction Set Architecture
A very important abstraction
interface between hardware and low-level software
standardizes instructions, machine language bit patterns, etc.
advantage: different implementations of the same architecture
disadvantage: sometimes prevents using new innovations
True or False: Binary compatibility is extraordinarily important?
Modern instruction set architectures:
IA-32, PowerPC, MIPS, SPARC, ARM, and others

22. MIPS R3000 Instruction Set Architecture
Registers
Instruction Categories
Load/Store
Computational
Jump and Branch
Floating Point
coprocessor
Memory Management
Special
R0 - R31 PC HI LO
3 Instruction Formats: all 32 bits wide OP rs rt rd sa
funct OP rs rt
immediate OP
jump target

23. Historical Perspective
ENIAC built in World War II was the first general purpose computer