1. CSC235 Computer Organization & Assembly Language
Introduction, Virtual Machines

2. Modern computing machines
Complex devices
Built using very large scale integrated circuits (VLSI)
Complex architectures
Programmable
“User friendly” high level languages: C++, Java, Python…
But a lot goes on to support this…

3. Goal of this course: Take a peak “under the hood” of a modern computer
Not absolutely necessary to use a computer
But… it will make you a better computer scientist!
Use a “ground-up” approach to learn about:
Digital Logic and Circuit Design
Machine architecture
Low level programming

4. Course Overview: Digital Logic Circuit Design
Examine basic principles of digital logic
Boolean operations
Binary Arithmetic
Circuit Design
Design basic logic circuits that implement logical and mathematical functions
Using “Logisim”
Combinatorial and sequential circuit design

5. Course Overview (cont):
Machine architecture
Examine major components of a computer
Central Processing Unit (CPU)
Arithmetic Logic Unit (ALU), Control Unit (CU), …
Memory
Discuss implementation using digital circuits
Concentrate on the Intel x86 family of processors
Underlying processor for Windows PC’s and Apple MAC’s

6. Course Overview (cont):
Low level programming
Machine code
Assembly Language
Basis for higher level languages like C++ and Java
MASM (Microsoft Macro Assembler)
Windows based assembler
Visual Studio
Use core libraries supplied with Irvine textbook

7. Virtual Machines Begin with the concept of a “Virtual Machine”
An abstraction
Computer is thought of as having multiple layers
Layers are a combination of software and hardware
Each level builds on capabilities of the lower level
Start with a simple 2 level abstraction…

8. Virtual Machines Tanenbaum: Virtual machine concept
Programming Language analogy:
Each computer has a native machine language (language L0) that runs directly on its hardware
A more human-friendly language is usually constructed above machine language, called Language L1
Programs written in L1 can run two different ways:
Interpretation – L0 program interprets and executes L1 instructions one by one
Translation – L1 program is completely translated into an L0 program, which then runs on the computer hardware
Irvine, Kip R. Assembly Language for Intel-Based Computers 7/e, 2015.

9. Modern computing machines
Digital
Large scale integrated circuits
Complex architectures
Binary arithmetic
Why? Easier to make circuits with only 2 states
as opposed to 10 (decimal)
More on this later…
Programmable
But at a very low level
Instructions, as well as data, are binary codes/numbers
Require many steps to accomplish even simple tasks
Not “user friendly”

10. Translating Languages
English: Display the sum of A times B plus C.
C++: cout << (A * B + C);
Assembly Language:
mov eax,A
mul B
add eax,C
call WriteInt
Intel Machine Language: A F E
Irvine, Kip R. Assembly Language for Intel-Based Computers 7/e, 2015.

11. Specific Machine Levels
(descriptions of individual levels follow )
Irvine, Kip R. Assembly Language for Intel-Based Computers 7/e, 2015.

12. High-Level Language Level 4 Application-oriented languages
C++, Java, Pascal, Visual Basic . . .
Programs compile into assembly language (Level 3)
Irvine, Kip R. Assembly Language for Intel-Based Computers 7/e, 2015.

13. Assembly Language Level 3
Instruction mnemonics that have a one-to-one correspondence to machine language
Programs are translated into Instruction Set Architecture Level - machine language (Level 2)
Irvine, Kip R. Assembly Language for Intel-Based Computers 7/e, 2015.

14. Instruction Set Architecture (ISA)
Level 2
Also known as conventional machine language
Executed by Level 1 (Digital Logic)
Irvine, Kip R. Assembly Language for Intel-Based Computers 7/e, 2015.

15. Digital Logic Level 1 CPU, constructed from digital logic gates
System bus
Memory
Implemented using MOS transistors
Irvine, Kip R. Assembly Language for Intel-Based Computers 7/e, 2015.
Modified John Carelli