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Primary Memory
Data Bus
Memory (address) Bus
MDR
MAR
ROM
RAM
ALU
CU
CPU (processor)
Output
Input
Prefix Conversions of bits and Bytes
TermSize in BUApprox. Size
Kilo (K)1.0241.000
Mega (M)1,024*21.000.000
Giga (G)1.024*31.000.000.000
Tera (T)1.024*41.000.000.000.000
8 bits=1 byte
Storage
Output
Process
Input
The CPU is in charge of processing input data into useful information. It retrieves and saves data to and from storage. 
Bits & Bytes
CPu > aka central proccesing unit
of the cpu
Components
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Components of the CPU from sections 2.1.1 and 2.1.2 of the IB Computer Science Course Book, Topic 2.

Transcript

Components

of the cpu

CPu > aka central proccesing unit

CPU components

Block Diagram

Bits & Bytes

bit = Binary digit of either 1 or 0

A bit is denoted by a lower case letter "b", and a Byte is denoted by an uppercase letter "B"

Output & Storage Model

Input, Process,

The CPU is in charge of processing input data into useful information. It retrieves and saves data to and from storage.

Input

Process

Output

Storage

8 bits=1 byte

Prefix Conversions of bits and Bytes

From higher prefixes to lower prefixes: to make this conversion we multiply by 1.024. Example: 2GBs = 2 x 1,024 = 2,048 MBS = 2,048 x 1,024 = 2,097,152 KBS From lower to higher prefixes: to make this conversion we divide by 1.024. Example: 2KBs = 2 / 1,024 = 0.001953125 MBS = 0.001953125 / 1,024 685 = 0.0000019073486328125 GBs

Input

Output

CPU (processor)

CU

The CU is responsible for the operation of the CPU. It RETRIEVES DATA from the primary memory and EXECUTES INSTRUCTIONS.

ALU

The ALU (Arithmetic Logic Unit) is in charge of performing all arithmetic, logical, and input/output operations using data (data for processing and instructions) provided by the CU.

RAM

The RAM (Random Access Memory) is in charge of storing program instructions and any other necessary data. The RAM stores data in memory locations that can be accessed by the CU and sent to the ALU for processing. The RAM is volatile, which means that when power is lost, the contents of the memory are lost as well.

ROM

The ROM (Read Only Memory) is in charge of storing instructions and necessary data, however, the stored information is permanent and cannot be changed. (generally stores instructions to boot and operate the computer). The ROM is non-volatile, which means that even if power is lost, data cannot be changed.

MAR

The MAR (Memory Address Register) is in charge of storing the memory address of data used by the ALU. The MAR may hold the memory address of the future storage location of processed data.

MDR

The MDR (Memory Data Register) is in charge of storing data used by the ALU and then saved to the RAM. Interaction of the MAR and MDR:

  1. MAR loads memory address (MA) into MDR and the ALU.
  2. The ALU places result into the MDR
  3. Data is copied to MA in the RAM which is specified by the MAR.

Memory (address) Bus

The Memory (Address) Bus is in charge of connecting the MAR with the Primary Memory to retrieve and save data to and from the RAM.

Data Bus

The Data Bus is in charge of connecting the Ram and the MDR. It carries data to the MDR and the ALU and then carries the processed data from the ALU to the MDR and the RAM.

Primary Memory

The storage keeps data that can be accessed by computer if it is required during the process stage.

Compters accept data or instructions as input, this data is received through input devices (keyboards, sensors, mouse, etc).

Processed computer data that the user can SEE and USE. The output info is also saved in the storage.

Inputted data is processed into information we can use. The data is processed by the CPU.

Differences between RAM and ROM:

  • ROM cannot be over-written, but RAM can be over-written.
  • ROM stores the BIOS (Basic Input/Output System), RAM stores the programs and data used.
  • ROM is smaller in size than the RAM.
  • ROM is non-volatile (permanent), and RAM is volatile (not permanent).