CS255 Syllabus & Progress

Material covered are displayed in blue.

Search the lecture notes:

Intro to CS255: click here

Intro to Computer Architecture

What is a computer - introduction to programmable computing devices:
- Devices that help humans do computing: click here (show pictures)
- Devices that can be programmed: click here (show pictures)
- Computer: a programmable computing device click here (show pictures)
Structure of a computer:
- What the inside of a computer looks like: click here (show pictures)
- Functional/logical structure of the computer:
  - Logical components of a computer and their functions: click here
  - What can the computer system do: click here
  - What can the peripherals do for a computer system: click here
  - So if a computer can only execute arithmetic and logical operations, how can it drive a car ??? click here
- Inter-connecting the various parts of the computer: click here

The Computer System (details of the memory and the CPU)

The computer memory (RAM):
- Introduction to Computer memory click here
  - Computer memory and binary numbers: click here
  - What can you do with only binary numbers ?: click here
- Structure of computer main memory: click here
- What can computer memory do (function): click here
  - The effect of the number of wires in the data bus and address bus: click here
- Storing non-numerical information in computer memory: click here
The Central Processing Unit (CPU):
- The structure of the Central Processing Unit (CPU): click here
  - Usage of the general purpose registers: click here (***)
  - Program flow and the usage of the special purpose registers: click here (***)
- The Instruction Execution Cycle of the CPU: click here (I kept an older page: click here)
  - Details of the Instruction Execution Cycle with diagrams: click here (***)
  - Out-of-order program flow - branching: click here (***)
Exposition of the program reference concept: click here

The computer program - from the perspective of a Java programmer and a computer

The program translation process: click here
Program organization (where different parts of the program is put in memory): click here

Homework 1 re-enforces computer architecture concepts: click here

Before we can explain how the computer works - i.e., how it manipulates data, we must understand how information are stored inside the computer...

Storing Boolean data inside a computer

Introduction to information representation: click here
Storing Boolean values inside the computer: click here

Storing numerical data inside a computer

Storing unsigned integral values inside the computer:
- Numeric values: click here
- Positional value representation: click here
- Representing unsigned integers: click here
- Arithmetic with binary numbers: click here
- Arithmetic with base-5 numbers: click here
Other number systems that are related to the Binary number system (condensed representation of bit patterns):
- Octal numbers: click here
- Hexadecimal numbers: click here
Storing signed integral values inside the computer:
- Introduction - signed-magnitude representation: click here
- Prelude to 2's complement code: the 10's complement encoding: click here
- The 2's complement number encoding:
  - How are signed numbers encoded inside the computer (2's complement code): click here
  - The int, short and byte data types of Java: click here
  - Converting between the different integer types (int, short and byte): click here
- The "Excess-n" codes: an alternate binary encoding for signed values: click here
- So many codes - how to tell which code we are used (context)? click here
Storing fractional numerical values inside a computer:
- Fixed point numbers: click here
- Floating point numbers
  - Floating point representation: click here
  - Floating point round off error: click here
Converting between integer and float data representations: click here
Data type revisited: what is the value that is stored in these memory cells ? click here

Homework 2 re-enforces number system concepts: click here

Representing text data inside the computer:

ASCII code: click here
Unicode: click here
Human/Computer communication (explains the need for conversion from ASCII to other representation and vice versa):
- Introduction: input/output click here
- String: array of ASCII character codes click here
- Example application of ASCII code: email click here
Boolean input and output:
- How to enter Boolean inputs - converting between ASCII String representation and Boolean representation: click here
- How computers print out Boolean outputs - converting between Boolean representation to ASCII String representation: click here
Numeric input/output - Converting between ASCII String representation and int 2's complement representation:
- Introduction: click here
- Java pre-requisite on Character/String manipulation:
  - Computing with ASCII codes in Java: click here
  - Java statements that manipulate characters and strings: click here
- How to enter integer inputs - Conversion algorithm ASCII representation -> 2's complement representation:
  - Intro: what is the problem when you enter an integer number ? click here
  - The trivial (but not-practical) solution: click here
  - Converting a string of 1 digit integer to 2's complement representation: click here
  - Converting a TWO DIGIT decimal integer string to 2's complement representation click here
  - Converting any decimal integer string to 2's complement representation click here
- How computers print out integer values - Conversion algorithm 2's complement representation -> ASCII representation :
  - Intro: what is the problem when the program prints an integer number ? click here
  - The trivial (but not-practical) solution: click here
  - Converting a 1 digit decimal number to ASCII representation: click here
  - Converting a TWO-digits decimal number to ASCII representation: click here
  - Converting any decimal number to ASCII representation: click here
  (My old notes on conversion algorithms: click here)

Project 3 re-enforces string ⟷ 2's complement conversion: click here

Representing computer instructions inside the computer (intro to hardware):

Intro: what kinds of instructions can a computer execute ? click here
Encoding computer instructions: click here
Fixed length (RISC) vs. variable length (CISC) instruction formats: click here
Sample instruction encodings:
- M68000 Instruction encoding: click here
- ARM Instruction encoding: click here

Intro to assembler programming using the ARM processor

Introduction: click here
The ARM processor's CPU architecture:
- The ARM processor from the point of view of an assembler programmer: click here
- How are the general purpose registers used in assembler programs: click here
- EGTAPI's display of the registers: click here
The "Hello World" program in assembler programming language: click here
Program organization illustrated using the "Hello World" assembler program with the help of EGTAPI: click here
What does an assembler program contain ? (directives and instructions): click here

The ARM assembler directives

ARM assembler directives used in the CS255 course: click here
The .text section of an assembler program (and labels): click here
The .data section of an assembler program (and labels): click here
- Alignment requirements: click here

Computing with integer values (integer constants and simple integer variables)

Introduction: click here
Moving an integer constant into a register
- Moving a small integer value into a register: click here
  - Moving/copying an integer value from one register into another register: click here
- Moving any integer value into a register: click here
- Moving an address into a register: click here
Using (the value stored in) a simple memory variable: click here
Updating (the value stored in) a simple memory variable: click here
Initializing and copying variables - simple high level programming statements in assembler: b = 4 and b = a click here
Store-ordering in memory: big and little endian ordering click here
What happens when you use an incorrect load/store instruction: click here
Arithmetic operations (instructions): click here
Assignment statement involving (only) simple variables: the c = a + b statement in assembler click here

Project 4 re-enforces the use of move, load and store instructions: click here

The array data structure (teach with demo/asm/3-array/demo.s)

How is an array data structure stored in computer memory: click here
Defining an array in assembler: click here
How to access an element in an array: click here
Load and store instruction formats used to access array data: click here
Assembler programming examples of accessing array: click here

The linked list data structure (teach with demo/asm/4-linked-list/demo1.s and demo2.s)

How is an object stored in memory: click here
How is a linked list stored in memory: click here (I kept my old note here: old)
Defining the head reference variable to a link list in assembler: click here
How to access a field in a (specific) list element: click here
Assembler programming examples of accessing fields in a linked list: click here
An example showing all the accessing techniques to simple variables, arrays and list data structures: click here
Inserting a list element at the start of a linked list: click here

Project 5 re-enforces access technique to structured variables (arrays and linked lists): click here

Summary: ARM assembler programming techniques used in CS255: click here
A single sheet summary of ARM instruction nmenomic codes : click here
Documentation - the complete ARM Instruction set and encoding (not part of syllabus material): click here

Now you know what the computer actually does when it executes an assignment statement: how it evaluates an expression and assigns the result to a variable in a high level programming language. We will discuss various program flow control structures next.

The Selection (if, if-else) Statements:

Introduction: click here
Branching - out of order program flow: click here
How is the branch instruction implemented ? click here
The Compare (cmp) and Branch (beq, bne, blt, ble, bgt, bge, bal) assembler instructions of ARM: click here
Coding Selection statements in assembler:
- If-statement with a simple condition: click here
- If-else-statement with a simple condition: click here
- Compound condition using and: click here
- Compound condition using or: click here

The Loop Statements:

While-statment: click here
For-statment: click here
Do-statment: click here.
Traversing linked lists: click here

Project 6 re-enforces the use of compare and branching in writing your first assembler program containing a while loop and if-statements: click here

The midterm test will cover the material upto this point and will be scheduled soon.

Now you know what the computer actually does when it runs a program. The only thing that you still do not know is what happens in a function call (there is still a lot to learn...).

Subroutines (a.k.a. methods, procedures, functions)

Introduction: click here
Leaf subroutines and Non-Leaf subroutines: click here
Leaf subroutines: subroutines (= functions) that do not call any function
- Let's try to use what we have learned (branch) to implement subroutine call: click here
- Calling a functions - ARM's bl (branch and link) instruction: click here
- Returning from a leaf subroutine click here
Non-leaf functions -- functions that calls another function....
- What happens when a called function calls another function: click here
- The program stack of a running program: click here
- The ARM assembler push and pop instructions: click here
- Implementing non-leaf methods/functions using the program stack: click here
Using the non-leaf function technique to implement leaf functions: click here

Implementing other features of methods/functions: (1) Parameters, (2) Return Values and (3) Local Variables CPU registers

Introduction: click here
Prelude to using register to pass parameters and store local variables: click here
Passing parameters to a function and passing return values using CPU registers:
- Intro: using CPU registers to pass parameters and return values: click here
- A skeletal example: click here
- A fleshed out example - using CPU registers to pass parameters and return values click here
Allocating local variables using CPU registers: click here

Project 7 (Bubblesort) re-enforces the use of registers for passing parameters and storing local variables: click here
Problems when using CPU registers to store parameters and local variables: click here
Passing parameters and allocating local variables using the program stack:
- Intro: using the program stack to store parameters and local variables: click here
- Why can the stack avoid the overwrite problem in registers: click here
- How a subroutine returns --- tearing down a stack frame: click here
- Summary and a "How to" guide: click here
- A skeletal example: click here
- A fleshed out example of passing parameters and allocating local variables using the program stack: click here
Another usage of the program stack - saving registers in an interrupted computation: click here

Recursive subroutines/methods:

Introduction: click here
First recursive method in assembler, the classic factorial function: click here

Second recursive method in assembler, the Fibonacci function: click here

Programming project pj8 re-enforces storing parameters and local variables on stack with a recursive function: click here

I inserted some material here to help you understand how to write program using the recursion technique --- these material are not part of CS255 curriculum:

Recursion is a divide and conquer technique to solve problems:
- How to design recursive algorithms: click here
- Tower of Hanoi click here
  A Tower of Hanoi game page: click here
- A tougher example of divide and conquer using recursion: click here

But I will discuss these webpages (quicker than usual) to help you understand the next topic: use recursion to manipulate linked lists

Tower of Hanoi in ARM assembler code: click here (skipped for brevity - read through it yourself)

Recursion with linked lists:

Introduction: click here
Remember how linked lists are stored inside the computer: click here
Searching for an element in a linked list using a recursive algorthm:
- Designing a recursive search algorithm: click here
- Implementing the recursive search algorithm in ARM assembler code: click here
Inserting a new element at the tail of the list using a recursive algorthm:
- My CS170 page on designing a recursive "insert at tail of list" algorithm: click here
- Implementing the recursive "insert at tail of list" algorithm in ARM assembler code: click here

Programming project pj9 re-enforces recursion with inserting in an ordered linked list: click here

Parameter passing techniques:

Introduction: click here
Implementing Pass-by-value and Pass-by-reference mechanism in assembler: click here
Important note: click here

If you understand everything so far, you now know exactly what is going on when a computer executes a program. You can apply what you learn and write assembler programs in any assembler language, e.g., Intel Pentium, IBM PowerChip, DEC Alpha, SunMicrosystem SPARC... To program with a new chip, all you need to learn are:

its architecture (registers),

the addressing modes

the instruction mnemonic codes and what they do.

I have Intel assembler programming material after the C lecture notes to demonstrate this process. (These notes are not part of the CS255 curriculum - it's "for your eyes only")

Introduction to the (System Programming Language) C for Java programmers

Introduction to C programming: click here
Things that are identical in Java and C (I have highlighted things that are different in blue): click here
How a CS professional should learn a new programming language: click here
Introduction to the C Pre-processor:
- Intro: click here
- Comments in C (/* ... */ or // ... ): click here
- Macros (#define): click here
- Including files (#include): click here
- Conditional compilation: click here
- A trick to prevent a file being included multiple times: click here

C's data types and variables:

C's data types: click here
Defining variables in C: click here
Defining and declaring variables: click here
The const data type modifier: click here
C's expressions: (minimal casting !!!)
- Operations involving same and different data types: click here
- Conversion rules in C: click here

Basic input/output:
- Printing values of the built-in data types: click here
- Reading in values of the built-in data types: click here
Operators:
- Arithmetic Operators: click here ( +, -, *, / )
- Bit-wise-Operators: (used in CS350)
  - The bit-wise operators: ( &, |, ^, ~ ) click here
  - How to use the bit-wise operators: click here
  - Denoting bit patterns using values in base 2, 8 and 16: click here
  - Bit manipulation functions - clear a bit, set a bit, flip a bit and test a bit: click here
- Shift-Operators: (used in CS350) click here ( >>, << )
  - Intro: click here
  - Set bit at position n: click here
  - Clear bit at position n: click here
  - Flip bit at position n: click here
  - Test bit at position n: click here
- Assignment Operators: click here ( +=, -=, *=, /=, &=, |=, ~=, >>=, <<= )
- Increment/decrement Operators: click here ( ++, -- )
- Boolean data type and operations:
  - The Boolean data type and Boolean values in C: click here
  - Compare and Logic Operators: ( <, <=, >, >=, ==, !=, &&, ||, ! ) click here
  - Boolean variables in C: click here
- The conditional operator ?: click here
- The comma operator , click here
- The sizeof operator click here
- Priority and Associativity of the C operators click here
Statements:
- Assignment Statement: click here
- Selection Statements (if, if-else, switch): click here
- Loop Statements (while, for, do-while): click here
Arrays: (C has static arrays, Java has dynamic arrays)
- Defining and using one-dimensional array variables: click here
- Review: static and dynamic arrays: click here
- Array bound checks: click here
- Defining and using two-dimensional array variables: click here
- Declaring array variables: click here
- "Bit" arrays: click here
Function (= method) definition:
- Defining and calling a function in C: click here
- Array parameters click here
- No overloaded functions in C !!!! click here
- The Parameter passing mechanism of C: click here
- Automatic conversion of parameter types and return value types in function call:
  - Programming principles in a function call: click here
  - Automatic type conversion in function calls: click here
Function declaration:
- Implicit function prototyping in C: click here
- Function declarations and their scope: click here
Multi-files C programs - the importance of declaring functions:
- Introduction to multiple file compilation: click here
- How to compile a multiple files C program: click here
- The importance of function declaration in multi-file C programs: click here
- Declaring function using header files: click here
The make (UNIX) utility: (Make will not be covered in the final)
- Specifying dependency between files --- makefiles: click here
- Structure of "make files": click here
- The make utility: click here
- Example of make file for a multi-file C program project: click here
- If time permits:
  - Inference rules used in makefiles: (if time permits) click here
  - Macros in makefiles: (if time permits) click here
  - Miscellaneous makefile stuff (line continuation, comment, ...): click here
Hand out C Project 1: click here
Intermediate topics: language features that are available in C and Java but work differently
- User-defined types: (i.e.: structures)
  - Defining and using struct type and variables: click here
  - typedef: giving a (shorter) name to struct click here
  - Always use header files to store the struct's and typedef's in your C program: click here
  - struct parameter variables are passed-by-value: click here
  - Size of a struct "object": click here
- Life time and scope of variables in C:
  - Review: Life time and Scope of the variables: click here
  - Kinds of variables in C: click here
  - Life time of variables in C (and when is a variable initialized ?): click here
  - Scope of variables in C:
    - Scoping rules for: (1) global, (2) static global and (3) static local variables: click here
    - Scoping rules for local and parameter variables in C: click here (pay attention !)
- Applying the scoping rules --- how to make sure variables in a C program are accessible in multi-files C programs
  - Intro: accessing variables in a multi-files C programs: click here
  - Making global variables accessible in multi-files C programs through declaration: click here
- Debugging a C program: (debugging will not be covered in the final)
  - Using the gdb debugger: click here
  - Debugging with printf: click here
C language features that are not found in or different from Java (pointer data type !)
- The reference data type and reference (pointer) variables (Java does NOT have this data type !!!)
  - Reference (pointer) data type and variables: click here
  - The reference (&) operator click here
  - Storing the result of reference (&) operator in reference data typed variables: click here
  - Using reference variables --- the dereference (*) operator: click here
  - First application of reference variables: pass parameters pass-by-reference: click here
- Pointer to user-defined type:
  - Pointer to user-defined (struct) variables: click here
  - The short-hand operator ->: click here
- Using pointers to create and maintain linked lists in C:
  - Introduction to linked lists in C: click here
  - Memory management - you must de-allocate list elements when you delete them !!! click here
  - Insert at head of list: click here
  - Delete at head of list: click here
- Pointer arithmetic and Arrays
  - Pointer arithmetic: click here
  - Accessing arrays with pointers : click here
  - The [ ] operator: click here
    CS255 repeat final will cover upto here
  - The equivalance of pointers and arrays in C: click here
  - Using the [ ] operator to implement Dynamic arrays: click here
  - The ++ and -- operators used in pointer arithmetic: click here
- Take a look at precedence and associativity of the new C's operators that you have learned: click here
- Strings in C --- arrays of char: click here
- Some Strings functions in C Standard library click here
- Array of Strings --- command line arguments: click here
Miscellaneous topics in C
- Special kinds of variables in C:
  - register variables: click here
- Function parameters:
  - Passing a function as a parameter to a function: click here
C documentations:
- The C99 standard: click here
- Obituary of Dennis Ritchie (co-inventory of C): click here
That's all, Folks !
Additional Enrichment Material: Intel 80x86 programming (not covered in CS255)
- A free Intel Macro Assembler (if you want to write assembler on your PC): RIGHT click here and SAVE AS
- An online documentation on Assembler programming with MASM: click here
- Intel Assembler Code Table: click here
- The Intel 80x86 CPU architecture: click here
- The Intel 80x86 directives: click here
- The Intel 80x86 Addressing modes: click here
- Arithmetic operations: click here
- Compare and Branch: click here
- Subroutine call and return: click here
- The Art of Assembler Language Programming book: click here
  Check out chapter 6
Rough notes on Intel Assemler programming:
- Intel registers: click here
- Intel registers: click here
- Reserving space for variables: click here
- Addressing modes (MOV): click here
- Arithmetic: click here
- CMP and Jump: click here
- Stack, procedure call/return: click here
Other resources:
- Matloff GNU assembler programming tutorial: click here
- Sourceforge GNU assembler programming tutorial: click here
- Free Intel Macro Assembler (if you want to write assembler on your PC): RIGHT click here and SAVE AS
- Intel Assembler Programming book - this book is like the CS255 course using Intel Assembler code: click here
- Step by step Windows programming tutorial shows you how to write window programs, menus, call backs, etc: click here
- The Art of Assembly Programming (a very good online book, but the 32 bit version uses a non-standard assembler called "HLA" - High Level Assemble language) click here