Topic 2 - Computer Architecture

• The program counter (PC) holds the memory address of the next instruction that is going to be read/written to • The address is transferred to the MAR via the address bus • The MAR sends the memory address to RAM via the address bus to signal it to read the instruction at the specified memory address • The instruction is sent to the MDR via the data bus from the RAM and then copied into the CIR (Current Instruction Register) also via the data bus • The PC is incremented to the next instruction

• Th UI interprets and decodes the instruction in the CIR

• The ALU carries out the decoded instruction by performing arithmetic or logical operations • The ACC stores and accumulates the result of the calculations performed by ALU if needed.

Read only memory that stores the permanent and persistent instructions to boot up the computer (BIOS)

expensive before

It is not directly connected to CPU unlike primary memory

This is utilized when primary memory is overloaded. It works by sending less used data from primary memory to secondary memory in pages freeing up space in the primary memory. When primary memory needs the data sent again, it is sent back to the primary memory from secondary memory.

• Slower • Temporary

2 boxes next to each other with a gap in between 1 box = RAM 1 box = Hard disk (but secondary box inside it called Virtual memory (pagefile)) There are two arrows that connect the boxes. One arrow on the top going from RAM to hard disk called “less used data” One arrow under it going from hard disk to RAM called “data needed by the CPU”

Set of software that controls computer’s hardware and resources and provides services for computer programs

• User interface • Memory management • Multitasking

It is what facilitates the link between user and hardware

GUI CLI Natural LI (speak to computer like Siri) MBI (like CLI but no commands only menu options)

A role of OS. It refers to keeping tracking of storage devices, allocating the appropriate amount of RAM to programs in use and organizing and managing data files and folders.

A role of OS. The OS works with the BIOS and device drivers to translate signals from peripherals into instructions the system can understand and use.

A role of OS that allocates CPU time and resources to multiple programs in use, allowing them to run concurrently. This process is often managed using time slicing and ensures each program gets a fair share of CPU time based on priority and scheduling algorithms.

A role of OS. It involves the setting of usernames and passwords, setting user permissions and file permissions for reading and writing throughout the OS to enhance security.

• Word processor • Spreadsheets • Web Browser

1 byte = 8 bits 1 kb = 1024 bytes 1 mb = 1024 kb 1gb = 1024 mb 1 tb = 1024 gb

Binary digit. This is a measurement unit that can only have two states, 1 or 0 (or on or off)

1 byte

Base 2

These more efficiently represent large binary values. These are base 16.

• HTML colors • MAC addresses • IP addresses