Elements of Computer Architecture

Hardware

comprised of physical, tangible parts.

Example: CPU, monitor, motherboard

Software

comprised of programs and operating systems.
Example: Windows, Linux, Microsoft Office, Zoom

Programs

composed of collections of instructions and procedures
that perform specific tasks on a computer.

Windows Command Line (CMD)

Windows’ text-based command interpreter that lets users interact with the computer by typing commands.

WMIC (Windows Management Instrumentation Command-line)

utility that queries, configures, and manages system settings via the WMI framework.

Binary: computers use the binary system, a system with two states. passing current or no current —> 1 or 0 ← called bit

true

How does the computer run a program?

The program is stored in RAM (memory cells with binary addresses), and the CPU executes it using the fetch–decode–execute cycle.

Von Neumann Architecture

• One shared memory unit for program instructions and data, and one bus for memory access.

• One arithmetic unit and one program control unit.

• Instruction is fetched from memory and decoded, then relevant data is
  fetched, then instruction is executed.

• Requires at least two clock cycles to execute an instruction.

• Due to single memory unit and single bus, limited bandwidth causes a
  bottleneck situation.

• Most commonly used in PCs.
  

Harvard Architecture

• Two separate memory units: one for program instructions and one for

  data.

• A set of address and data buses to read and write data to memory, and another set of address and data buses to fetch instructions.

• Can fetch instruction and data simultaneously.

• Can execute an instruction in only one clock cycle.

• Faster and no bottleneck issues.

• Requires more memory and hardware.

• Most commonly used in embedded devices and signal processing.

• More and more modern computers are using this.

The algorithm can be described in a variety of ways

• Plain English

• Pseudo-code

• Flowchart

Pseudocode

• an artificial and informal language that helps
  programmers develop algorithms.

• "text-based" detail (algorithmic) design tool.

flowchart

a picture of the separate steps of a process in sequential

order. It is a generic tool that can be adapted for a wide variety of

purposes, and can be used to describe various processes, such as a

manufacturing process, an administrative or service process, or a

project plan.

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programming language

a formal language comprising a set of
strings that produce various kinds of machine code output.

Program code

Implementation of an algorithm in a programming language.

Compiled

-Compiler converts the whole program to executable (machine code) before running.

-Runs faster and compiler not required to run the executable, but is more complex to develop.

-Allows the developer to have more control over hardware specs, i.e., memory management, CPU usage.

Examples: C, C++, Java, Rust, Go

Interpreted

converts the program to machine code instruction by instruction.
Easy to debug but a little slower - always requires interpreter to run.
More flexible, offer dynamic typing and smaller program size.
Examples: Python, Javascript, PHP, Ruby.

Strongly typed

A language that requires variable and object data types to be specified (integer,
string, float).
Allows for more structure, but less flexible

Loosely typed

A language that does not require variable and object data types to be specified.
More flexible and faster, but errors are more likely to occur.
Examples: JavaScript, Perl, Python, Ruby.

Fetch–Decode–Execute

1. Fetch Instruction (Control Unit → Main Memory):

The CPU’s Control Unit gets (fetches) the next instruction from Main Memory and stores it in a register.

2. Decode Instruction (Control Unit):

The Control Unit decodes the fetched instruction, figuring out what needs to be done.

3. Get Data (ALU → Registers/Main Memory):

If the instruction needs data (like numbers for a calculation), the CPU retrieves it from memory or registers.

4. Execute Instruction (ALU):

The Arithmetic Logic Unit (ALU) carries out the action (e.g., add, compare, move data).

Results may be stored back in registers or main memory.

👉 Then the cycle repeats for the next instruction.