CS Revision EOY (weak terms)

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Define embedded system (2)

Microprocessor-based system within a larger-scale machine that is designed for a specific task

Role of microprocessor in a control system (3)

1) Input: The microprocessor takes in inputs from various sensors

2) Comparison: Compares sensor signals with predefined values

3) Signals output: Sends signals to output transducers/actuators

Explain how the OS manages interrupts (4)

1) Priority: OS identifies priority of the interrupt

2) Pause: Suspends the current process

3) Interrupt handler: Transfers control to the interrupt handler

4) Resume: Resumes process once interrupt is handled

Explain why hexadecimal numbers are used for shorter representation of data (3)

A single hexadecimal digit contains 4 binary digits, a direct 1-to-4 mapping. Computers store and handle binary digits so they are able to read hexadecimal numbers. This condenses long binary numbers and improves human readability by shortening it into a more readable format.

Distinguish between data and information (3)

Data is raw, unprocessed, and unstructured building blocks, information is data that has been processed, structured, and contextualized so it becomes meaningful and usable for decision-making

Define data integrity (2)

The accuracy, consistency and completeness of data throughout its different lifecycles

State the purpose of MDR (1)

Holds the data of the instruction that will be stored into/fetched from primary memory

Define primary key (2)

A field that uniquely identifies each row of a table

Outline the purpose of a database schema (2)

To define the structure of the database, defining tables, fields, and relationships

State where the program is held (1)

RAM

Explain the importance of data types in a database table (4)

1) Ensures that only valid data is entered.

2) Defines how the computer should store and process data

3) Optimizes storage space

4) Prevents errors during calculations

Identify three potential causes of data loss (3)

1) Accidental deletion

2) Hardware failure

3) Malicious activity

Identify two characteristics of a relational database (2)

1) Data is stored in tables

2) Tables are linked by keys

Outline the steps involved in the FDE cycle, specifically how the PC is updated (4)

1) Address fetched from PC

2) PC increments by one to point to the address of next instruction

3) Instruction sent to the MDR

4) Sent to the IR to be decoded

Explain the steps involved in the FDE cycle, making reference to MAR and MDR (5)

1) MAR stores the address of the next instruction

2) That is to be read from RAM

3) Data is then sent from RAM to MDR

4) The instruction is decoded by the CU

5) Executed by the ALU

Outline one reason for using Unicode to represent data in a computer system (2)

Unicode is a standardized encoding system that represents data, including unique symbols and characters, so that data can be transported through many devices

Outline two purposes of paging as as OS resource management technique (4)

1) To remove fragmentation by divinding memory into equal blocks of memory so that there is no wasted space

2) To enable processes to access virtual storage so that when a process tries to access a page not in RAM, OS brings in a page from secondary memory

Outline the primary purpose of secondary memory in a computer system (2)

To provide permanent, non-volatile storage for data that is not frequently used, because primary memory is volatile and loses data when power is turned off.

A database transaction occurs when a patient pays their bill at a clinic. To maintain data consistency and integrity during the transaction, the database goes through several states. Describe the change in database states when a transaction is updated. (3)

1) Initial state: Patient’s account shows a balance. It is in a consistent state.

2) Transition state: During payment processing, patient’s records are temporarily locked for updating. Intermediate state.

3) Final state: After successful payment, a new balance is shown, returning the database to a consistent state.

Log files are stored prior to database updates. If the database crashes, the log files are used to recover the database. Describe the steps used in log recovery when a database crashes. (3)

1) A consistent version is returned from backup logs

2) The log file is scanned to determine its most recent checkpoint

3) Committed transactions are redone and non-committed ones are rolled back.