Experiment 1

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Experiment 1

• COE 205
• Computer Organization Assembly Language
  Programming
• Term 032

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Outline

• Definition of a program.
• Instruction atomicity.
• Stored-program concept.
• Programming early computers.
• Assembly language.
• Tools.
• Setting up the environment.
• Policy.

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Definition of a Program

• A mix of instructions and data that causes a
  machine to perform one or more operations.
• An operation has two elements
• ? Instruction(s)
• ? Data

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Instruction Atomicity

• An instruction is atomic.
• ? Indivisible
• ? Non-interruptible operation
• Hardware ensures the non-interruptible execution
  of an instruction.
• A complex operation is made of simple
  instructions.
• ? Multiplication
• - AND For 2-bit multiplication
• - Shift
• - Add

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Stored-Program Concept

• Data instructions are stored in the memory.
• Central Processing Unit (CPU) loads instructions
  from memory one by one.
• Instructions are executed in sequence.
• User interacts with the system via Input/Output
  (I/O) devices.

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Programming Early Computers

• Computers were programmed by hand.
• Front panel switches were used to enter
  instructions and data into memory.
• Each instruction and data element was manually
  converted into bit patterns.
• ? Bit pattern of an instruction is called a
  Machine Instruction.
• To enter instruction/data into memory
• ? Address switches were toggled to the correct
  address.
• ? Next, data switches were toggled.
• ? Finally, write switch was toggled to write the
  binary value to the address specified.
• Once all instructions and data entered, the RUN
  switch was toggled to run the program.

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Major Drawbacks

• Dealing directly with instructions, data, and
  addresses in binary format.
• Manual conversion into bit patterns.
• ? Slow
• ? Cumbersome
• ? Error-prone

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Major Milestones

• Monitor programs became popular.
• ? Allowed entry of instructions and data via hex
  terminals.
• Paper tapes and punched cards became popular as
  storage methods for programs.
• To increase programmer productivity, assembler
  (or assembly) language was invented.
• ? An assembler takes machine instructions in
  human-readable form and translates them into
  binary automatically.

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Features of Assembly Language

• Raw binary values were replaced by symbols called
  mnemonics.
• ? Changes could be made easily and faster.
• Automatic translation into machine language.
• One-to-one mapping to machine language.

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Disadvantages of Assembly Language

• The programmer requires knowledge of the
  processor architecture and instruction set.
• Programs are machine dependent (Not Portable),
  requiring complete rewrites if the processor is
  changed.
• Many instructions are required to achieve small
  tasks (HL vs. LL).
• Source programs tend to be large and difficult to
  follow.

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Why know Assembly Language?
We do not have to learn assembly language. It is
enough to learn a high-level language, like C or
Java. We can get by fairly well in todays world
without knowing any assembly language.
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Reasons for Learning Assembly Programming

• Knowing an assembly language helps you understand
  what is happening inside a computer.
• When writing hardware drivers or software for
  embedded systems, you will need to code and debug
  in assembly language.
• Using assembly language lets you control exactly
  what happens in your program.
• Assembly programs runs fast and conserves memory.

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Tools

• MASM 6.11
• ? Assembling linking
• ConTEXT
• ? Editor
• Code View
• ? Debugger
• XVI32
• ? Hexadecimal editor

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Setting Up the EnvironmentStep 1

• Get the tools and install them on your machine.
• ? For MASM 6.11 ConTEXT, use the setup files
  and keep the default options.
• ? For XVI32, copy the application program XVI32
  into your hard disk.
• ? For Code View, it is part of the MASM 6.11
  package. It is run by entering CV at the command
  prompt.

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Setting Up the EnvironmentStep 2

• Create a new directory on your hard disk and call
  it COE 205 Experiments.
• For every new experiment, you should have a new
  sub-directory in the root directory COE 205
  Experiments.

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Setting Up the EnvironmentStep 3

• To be able to open a DOS screen from within
  ConTEXT, do the following
• 1. From the OPTIONS menu, choose Environment
  Options.

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2. Choose Execute Keys tab.
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3. When you press on the Add button, a dialog box
will appear. Enter asm and press OK.
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4. Choose F9 and type C\WINDOWS\system32\cmd.
exe in the Execute field. 5. Press OK.
Now, whenever you want to open a new DOS screen,
press on the F9 button on the keyboard.
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PolicyLab Sessions

• In every session, a programming problem will be
  given at the beginning of the lab.
• Concepts will be explained while the students are
  working on the problem.
• How to Prepare
• Try the sample programs in the lab manual.
• Study the related material from your class notes
  and textbook.

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PolicyLate Assignments

• You are supposed to finish all programming
  assignments in the lab.
• If you run out of time, you can send your
  assignment to the following email address.
• coe205_at_bareed.com
• Deadline is 1 am the next day.
• You lose THREE points for every late assignment.

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PolicyAbsence

• Three unexcused absences lead to a DN grade.
• Official excuse must be presented to the
  instructor no later than one week following the
  absence.
• Cheating is not allowed. Severe measures will be
  taken by the instructor.

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PolicyMark Distribution

• Lab weighs 20 of your final grade.
• 10 will be for lab work.
• 10 will be for the project.