40 terms

Computer Architecture

As shown in the Toy Machine and in the Powerpoint
STUDY
PLAY
Bus
Provides a pathway to transfer data to different parts of the computer (CPU, memory, peripherals, etc.).They are labelled "control", "data" and "address".
Data Processor
Part of the machine that contains the Arithmetic Logic Unit, the Temporary Registers, and the Registers.
It provides a faster form of storage than main memory.
Arithmetic Logic Unit (ALU)
Carries out all arithmetic and logical instructions. These include addition, subtraction, multiplication, division. It can also perform other operations, e.g. logic operations (AND, OR, NOT, XOR, etc.) and shifting left and right.
Is situated in the Data Processor.
Temporary Register (TEMP)
Registers used by the Arithmetic Logic Unit during computations. Is situated in the Data Processor.
Control Processor (Control Unit)
Part of the machine and consists of the hardware to perform the instruction execution cycle and to execute operations.

It moves instructions from RAM to a special register, carries out those instructions, and figures out where to read and write data. The _____________ __________ also regulates how fast the computer runs.
Program Counter (PC)
Contains the address of the instruction in memory to be executed next. Is situated in the Control Unit.
Memory Address Register (MAR)
Contains the address of a memory location to be accessed.
Is a type of register situated in the Control Unit.
Memory Buffer Register (MBR)
When a memory location is accessed this register holds the value extracted from or to be replaced in the location specified by the Memory Address Register. Is a type of register situated in the Control Unit.
Instruction Register (IR)
Contains the current instruction fetched from memory. Is a type of register situated in the Control Unit.
Instruction Decoder
Controls the action of all the microprocessor registers and the ALU through the timing and control section. It uses opcodes and operands. It is situated in the Control Unit.
Main Memory
Memory used to store instructions and data.
Fetch-Execute Cycle
In executing a program, a computer goes through a methodical process.
1. The computer fetches an instruction from memory
and then executes this instruction. The next instruction is fetched and then it is also executed. This process is continued; and each cycle only takes a few microseconds.
Secondary Storage
Responsible for keeping information for extended periods of time. This could be a hard disk, CD or DVD.
Central Processing Unit (CPU)
The heart of the computer. It performs all the work required for the computer's operation.
Random Access Memory (RAM)
It stores information but it is volatile storage. That means, it is temporary and whenever the computer is turned off, the storage is erased. It can be read from, as well as have data written to any memory location. However it is useful when the computer is running, because the CPU writes information to it, and reads information from it.
Read-Only Memory (ROM)
It stores information but provides non-volatile storage. That means, when the computer is turned off, its contents are not erased. It is used to store instructions and data that will never change. The contents of this storage cannot be changed, and the information on it can be read, but not written.

A small amount of permanent storage.
Instructions and Data (Data and Instructions)
The two types of information stored in RAM and ROM: I_________ tell the computer what to do. D____ is the input or result of an operation.
Random Access Memory (RAM)
Is known as primary memory. It is the primary location where information is stored while the computer is running.
Word
While a byte always consists of 8 bits, the number of bits in a _______ varies from one computer to another, and they are present in a computer's microprocessor. Common sizes of ________ in today's computers are 32 bits or 64 bits.
Memory Addressing
A number that is assigned to each byte in a computer's memory that the CPU uses to track where data and instructions are stored in RAM. Each byte is assigned a memory address whether or not it is being used to store data.
Cache Memory
A very small amount of rapid access storage

In addition to primary memory, most computers contain a special kind of memory called ________ __________. It is faster to access than primary memory, but much more expensive. ________ __________ is used to store recently accessed instructions and data.
Computers use _______ ___________ to improve their speed. Several different parts of a computer have their own __________ ___________. These include the CPU, video card and disk drive.

It's auxiliary, supplementary memory. It assists the operation of the computer.
Read-Only Memory (ROM)
It contains instructions that control how a computer starts up, reads input, and writes output.
1024 (2^10)
How many bytes in a kiloByte?
Register
Provides temporary storage of critical information. Special storage locations which are directly accessible by the CPU. Different computers have different numbers of these. It is situated in the control unit.
Control Processor (Control Unit)
Has functions including:
Timing
Instruction Selection (FETCH)
DECODE
Instruction Processing (EXECUTE)
Addressing (takes care of RAM)
Interrupt processing
Opcode and Operand (Operand and Opcode)
Each instruction consists of two parts: o________ and o_______
Fetch-Execute Cycle
The process of carrying out instructions takes place in four steps:
1. Fetch: Move the instruction from RAM into a special
Register
2. Decode: Determine what action is required
3. Execute: Carry out the action
4. Store: Save the result in memory or register
Opcode
Contains coded instructions. Written as the first 8 bits.
e.g. load, add, multiply, store
Operand
Tells you pieces of data and memory location. Written as the last 8 bits.
e.g. value of __________, address of __________
Accumulator
Stores the immediate results of arithmetic and logical operations. It is a special register.
Disk Cache
Stores part of the instructions on the disk (hard drive) as an extension of RAM. However it is a lot slower because it has to go through input/output ports.
Used if the program is too big to put in the RAM.

Much slower than its memory equivalent.
Interrupt Handling (Interrupts)
Temporary suspension of the Fetch-Execute cycle while it does another task (e.g. waits for data received from an Input/Output task).
A bunch of these at high speed create the illusion of multi-tasking and operating in a queue structure (FIFO).
Arithmetic Logic Unit (ALU)
Input - Gets data from memory and registers
Process - Performs arithmetic and logical operations
Output - Stores result in accumulator
Pipelining
Overlap
While one instruction is fetched, another instruction can be executed, another one can be stored.
Parallel Processing
The simultaneous use of more than one CPU or processor core to execute a program or multiple computational threads. Ideally, this makes programs run faster because there are more engines (CPUs or cores) running it.
Word Size
Determines the amount of data the computer will process in a single operation, and how much data can be transferred backwards and forwards, how much memory can be accessed in a single operation, etc.
It also checks compatibility.
Address Bus
A collection of wires connecting the CPU with main memory that is used to identify particular locations (addresses) in main memory.
Control Bus
The physical connections that carry control information between the CPU and other devices within the computer.
Data Bus
The bus used to carry data. The width of a ___________ bus refers to the number of bits (electrical wires) that make up the bus. Common _________ bus widths include 1-, 4-, 8-, 16-, 32-, and 64-bit.
Memory Location
Each location in memory has a unique address.
Each location contains 1 byte. Each byte has a different address. A byte is the smallest addressable unit of memory.
_____________ ________________ start at address 00000000