Introduction to The Architecture Of The Computer System
A computer is an electronic machine that makes any task easy to perform. In pc, the CPU executes every instruction given to it, this series of steps is called the Machine Cycle in a series of steps, and is repeated for each guidance. One system cycle includes instruction searching, operation decoding, data transfer, and operational execution.
The computer system has five basic units which are provided below to help the machine perform the operations:
- Entry Machine
- Unit Production
- Disposal device
- Arithmetic unit logic
The input device binds the internal computer system to the external world. It supports the Computer System with instructions and data. Input devices widely used are the keyboard, mouse, magnetic tape respectively.
The Input Device executes the following tasks:
- Accept data from the outside world and guidance.
- Convert it into the language of computers.
- Provide data translated to the computer system.
It connects a computer’s main system to the outside environment. It supplies the outside world with the effects of any calculation, or instructions. Some output devices are printers, tracking devices, etc.
This unit contains the instructions and the data. It also stores the intermediate data until they are being sent to the devices for processing. It also preserves the data for future use.
A computer system’s Storage Unit can be classified into two parts:
Main Storage: This memory is used to store the typically exist being conducted. It is used for transient data storage. When the machine is turned off the data gets lost. RAM is used as a primary memory for data.
Secondary Storage: Secondary memory is slower than primary memory and cheaper. It is used for permanent data storage. The secondary memory devices widely used are the hard disc, CD, etc.
Arithmetic Logical Unit
All calculations are carried out in the computer system ALU. The ALU can perform basic functions such as add, deduct, divide, multiply, etc.
The control unit transfers the data from the storage unit to ALU where calculations are needed. The output is moved back to the storage unit once the operations are completed.
It regulates all other computer equipment. It manages data flow and commands to and from the storage system to ALU. So it’s also recognized as the computer’s brainstem.
It is the Central Computer Processing Unit. The control unit and ALU are regarded as CPU combined. CPU is a computer system brain. It performs tasks such as:
- It does all of the operations.
- All decisions are taken.
- It controls all mechanical equipment.
Random Access Memory (RAM)
The memory cells can be reached in random-access memory (RAM) from any desired random location for information transfer. That is, the method of finding a word in memory is the same and takes an equivalent amount of time regardless of where the cells are placed in memory.
The connection between such storage and its environment is accomplished through the input and output lines of data, address collection lines, and control lines defining the transfer path.
Here is a flow chart of a RAM unit:
The n data input lines provide data that needs to be stored in memory, and the n data output lines provide the data that comes from the specific word selected in the 2k system memory. The two control inputs specify the direction of the desired switch.
Write and Read Operations in RAM
Write and read operations are the second part that contains that a random access memory will conduct. The write signal specifies a transfer-in operation, and a transfer-out operation is specified in the read signal.
On accepting one of these control signals. Inside the memory, the inner circuits provide the purpose you want. The steps to be taken to transmit a new word to be stored in the memory are as follows:
- Apply the desired term binary address into the address row.
- Apply data bits to the data input lines which must be stored in memory.
- Switch on write data.
- Then, the memory unit takes the bits currently available in the input data line stuff and stores them in the address lines stipulated.
The step to be followed to send a stored word out of memory areas continues to follow:
- Apply the required word binary address into another address row.
- Switch on the read video.
- The memory device will then take the bit from the word that the address has chosen and applied them to the lines of output data. After reading the chosen word meaning doesn’t alter.
Read-Only Memory (ROM)
A read-only memory (ROM) is, as the title suggests, a memory component that only needs to perform the read operation; it does not have write functionality.
This indicates that the binary information stored in a ROM and during the unit’s hardware manufacturing is made permanent and cannot be altered by writing different words into it.
Whereas a RAM is a general-purpose computer whose content can be modified during the physical system, a ROM is limited to saying things that are inevitability within the machine.
The binary information to be stored is then embedded in the unit to form the necessary interconnection pattern, as defined by the designer.
ROMs come with special electronic internal fuses that can be configured for a particular configuration. If the pattern is formed it persists within the device even when power is switched off and on again.
An m x n ROM is an array of binary cells arranged into m words of each n bits. As seen in the following block diagram, a ROM has k address input lines to pick one of 2k = m m memory words, and n input lines, one per bit of the phrase. An integrated circuit ROM could also have one or more activated inputs to expand the number of orders into a bigger-capacity ROM.
The ROM does not need a read-control line because the output lines automatically deliver the n bits of the word chosen by the address type at any given time.
Because the outputs are just a function of the current inputs (the address lines), a ROM is known as a combinational circuit.
In reality, a ROM with decoders and a collection of OR gates is installed internally. No need to have data storage as in RAM, because the values of the bit in the ROM are forever set.
ROMs find a wide spectrum of applications in digital system design. As such, any combination circuit with inputs k and outputs n can be implemented.
If used as a memory unit in a computer system, the ROM can be used for storing unchanged set programs and for sheets of constants not subject to change. ROM is also employed in the design of digital computer control units.
As such, they are used to store encoded data that represents the series of internal control variables necessary to allow the various software operations. A control unit that uses a ROM to store details regarding binary control is named a microprogrammed control unit.
Different Types of ROM
In a ROM the necessary paths can be configured in three main forms.
- The first, mask programming, is performed during the unit’s first fabrication phase by the semiconductor company. This method is expensive as the vendor pays the customer a special charge for custom masking the ROM in question. For this purpose, mask programming is economical only if you have to order a large quantity of the same ROM configuration.
- The second type of ROM called a Programmable Read-Only Memory (PROM) is more affordable to use for small quantities. The programming hardware process for ROMs or PROMs is irreversible, but once programmed the set template is irreversible and cannot be modified.
- A third available form of ROM is called erasable PROM or EPROM. The EPROM can be restructured to the initial value as its fuses were previously blown. Instead of ultraviolet light, some PROMs can be removed with electrical signals. These are known as Electrically Erasable PROM or EEPROM. Flash memory is a type of EEPROM that allows one to erase a block of bytes in a very short time.
Example EEPROM Implementations are:
- Present time and date are stored in a server.
- Store statuses for the port.
List of applications for Flash Memory devices are:
- Shop messages over a cell phone.
- Photographs are processed in a digital camera.
The memory stores binary (1’s and 0’s) information in bits called words. A term in memory is an object of bits that travel as a unit within and out of storage. The memory word is a group of 1’s and 0’s and can show us a specific number or any major details.
Byte To Byte
An eight-bit community is called a Byte. Most machine memories use words that have a multiple of 8 bits. Thus a 16-bit word includes 2 bytes, and 4 bytes form a 32-bit word.
Internal Structure of a Memory Unit
An internal memory unit structure is defined by the number of terms it contains, and the bit rate in each term. Select one specific word for special input lines named address lines.
An identity card, called an address, is assigned to each word in memory, starting from 0 and continuing with 1, 2, 3, to 2k-1 where k is the number of address lines. Selecting a particular word within the memory is achieved by adding the binary k-bit address to the line of addresses.
A memory decoder recognizes this address and opens the paths necessary to select the bits of the given word.
- K(Kilo) = 210
- M(Mega) says 220
- The G(Giga) levels 230
In computer systems, two main types of memories have been used: Random Access Memory (RAM) and Read-Only Memory (ROM). Such semiconductor memories are categorized by communication costs into Random Access Memories (RAMs) and Sequential Access Memories (SAMs).
Examples of SAMs include memories created with shift registers, Charged Coupled Devices (CCDs), or bubbles memories. Read Mainly Memories (RMMs) and Read Write Memories (ROMs) are classified into ROMs.
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There are 2 kinds of ROMs: Masked Programmed ROMs and Programmed User PROMs.
- Erasable and Programmable (EPROM) and Electrically Erasable (EEPROM) are two types of RMMs.
- Static RAM (SRAM) and Dynamic RAM (DRAM) are RWM. Static RAMs have Flip-Flops as typical memory cells. Dynamic RAMs have memory cells that need to be regularly refreshed, read, and written to prevent memory cell loss.
The primary issue of this course is to provide a broad analysis of computer architecture with special emphasis on designing reduced instruction set computers, enable the organization to understand the basic principles and tradeoffs and behind the development of new computer networks, such as cost/performance or speed/versatility. This course provides a framework for bridging the distance between the computer’s programming and its inner difficulties.