Data, Information and Memory

Question 1

What is a memory address?

Answer 1

A unique individual location in memory that stores 1 byte of information.

Question 2

What are variables?

Answer 2

Data created by computer programs and stored in memory at a specific address where they can later be accessed.

Question 3

How does the write function operate?

Answer 3

To store (Write) a value in memory, the CPU must write the value in the memory’s Data Register and the specify address where in memory it is to be stored in the Address Register. The CPU must also indicate a Write operation to memory using the R/W and control signals(wires).

Question 4

How does the read function operate?

Answer 4

To access (Read) a value in memory, the CPU must put the address of the location in memory to be read into the Address Register. The CPU must also indicate a Read operation to memory using the R/W and control signals. The memory responds by putting the contents of the location into the Data Register.

Question 5

What is machine code?

Answer 5

Programs in memory in binary is such that the program code can be directly understood and executed by the processor.

Question 6

What is a compiler?

Answer 6

Takes a HLL and converts it into the specific machine code of the processor that will execute it. Also generates a more human-readable form of the machine code specified called assembly language.

Question 7

What is the Von Neumann Architecture?

Answer 7

A programmable machine that can store, retrieve and process data. Consists of Input/Output, storage and CPU.

Question 8

List the CPU components.

Answer 8

-Registers
-Control Unit
-ALU Arithmetic Logic Unit

Question 9

What is the role of the register?

Answer 9

Store data in CPU (They are referenced by name not address e.g. Accumulator A.)
Update of registers controlled by Control Unit.
Data can come from or go to memory, ALU or other registers.

Question 10

What is the role of the ALU?

Answer 10

Performs operations, usually 2 inputs and 1 output per operation.
Controlled by signals from Control Unit.

Question 11

What are the functions and role of the Control Unit?

Answer 11

Control Unit:
Control Lines
Loads instructions from memory.
Decodes the instructions
Program Counter

Question 12

What is the memory address register?

Answer 12

contains the address of the memory location being referenced. The size of the address-register determines the range of addresses for memory.

Question 13

What is the memory data register?

Answer 13

contains the contents of the address that is read or written. Data-bus size called the Word size determines the maximum amount of data that transferred in 1 read or write operation.

Question 14

What are control signals?

Answer 14

Synchronise the transfer of data to/from CPU from/to memory.

Question 15

What is the instruction register?

Answer 15

holds the instruction currently being fetched from memory while it is being acquired from memory

Question 16

What is the status regitser?

Answer 16

The register is updated after the execution of every instruction, reflecting the status of the result.
Half carry (H) - set if there was a carry from bit 3 to bit 4 of the result when the result was calculated.
Interrupt mask (I) - set if the IRQ interrupt is disabled.
Negative (N) - set if the most significant bit of the result is set.
Zero (Z) - Set if the result is zero.

Question 17

What is the index register?

Answer 17

register usually used for temporary storage or as an index when indexed addressing is used.

Question 18

What is the instruction set?

Answer 18

The set of all possible instructions reference by op-codes that can be performed by the processor.