CPU and Memory Organization

Flashcards covering CPU components, register types, memory volatility, memory hierarchy, and byte ordering based on Chapter 3 lecture notes.

CPU (Central Processing Processing)

Interprets and carries out basic instructions that operate a computer; it controls the action, performs calculations, and manipulates data.

Microprocessor

An integrated circuit residing on a micro chip that contains all the functions of a CPU, including arithmetic, logic, and control.

Control Unit (CU)

Coordinates and directs most operations in the computer by interpreting the execution of instructions following a fetch-execute cycle.

Instruction Decoder

The part of the CU that interprets the bit pattern appearing in the instruction decoder register to determine how to proceed with the instruction.

Arithmetic Logic Unit (ALU)

Performs arithmetic operations such as addition, subtraction, multiplication, and division, as well as logical operations like AND, OR, and NOT.

Comparator

An ALU component that compares the magnitude of two numbers in buffer registers and outputs results in conjunction with the Status Register.

Shifter

A component that moves the contents of a register one or more positions left or right, and can perform rotate operations.

Registers

Temporary storage areas within the CPU that hold data and instructions before processing.

Instruction Register (IR)

A specific register that holds the actual instruction currently being executed by the computer.

Program Counter (PC)

Both a counter and a register that holds the address of the next instruction to be executed and increments by $1$ after each generation.

Memory Address Register (MAR)

Holds the address of the memory location that is to be opened for data retrieval or storage.

Memory Data Register (MDR)

Also known as the Memory Buffer Register (MBR); it holds the data value being stored to or retrieved from the memory location currently addressed by the MAR.

Status Register (Flags)

Keeps track of special conditions within the CPU, such as arithmetic carry and overflow.

Bus

A structure of parallel electrical lines or paths used for the specific exchange of data between various parts of the CPU and other components.

Clock

A device that produces a periodic sequence of pulses to synchronize all computer operations and control timing.

Clock Cycle Time

The interval between corresponding edges of two consecutive pulses generated by the system clock.

Machine Cycle

The combination of the instruction time (i-time) for fetching and the execution time (e-time) for processing an instruction.

RAM (Random Access Memory)

Volatile main memory used to store currently active programs and data; its contents can be changed or deleted.

ROM (Read Only Memory)

Non-volatile memory used to store fixed routines, such as boot-up routines, which cannot be changed or deleted.

DRAM (Dynamic RAM)

A type of RAM that is less expensive and requires extra electronic circuitry to refresh memory periodically.

SRAM (Static RAM)

Faster memory that does not require refreshing, often used for cache memory or in high-speed computers.

MRAM (Magnetoresistive RAM)

A type of RAM that stores data using magnetic charges, consuming less power and offering faster access times.

EPROM (Erasable Programmable ROM)

A type of ROM that can be programmed by the user and erased by exposure to ultra-violet light.

EEPROM (Electrically Erasable Programmable ROM)

A type of ROM that can be programmed and erased electrically using a concept called Fowler-Nordheim tunneling.

Flash ROM

A type of non-volatile memory similar to EEPROM that is faster and more flexible because it can erase and write data in blocks.

Access Time

The average time it takes a computer to locate data and read it, often measured in $\text{milliseconds}$, $\text{microseconds}$, or $\text{nanoseconds}$.

Data Transfer Rate

The amount of data that moves per second, often measured in $\text{KB/sec}$.

Memory Capacity Formula

If an address scheme has $m$ bits, the maximum number of cells directly addressable is $2^m$.

Gigahertz (GHz)

A measurement of clock speed representing one billion ($10^9$) ticks per second.

Megahertz (MHz)

A measurement of clock speed representing one million ($10^6$) ticks per second.

Big-endian

A byte ordering method where bytes are numbered from left to right, commonly used in the Motorola family (6800).

Little-endian

A byte ordering method where bytes are numbered from right to left, commonly used in the Intel family (8086).