TASK4
AIM: Introduction to Memory and Storage Devices, I/O Port, Assemblers, Compilers, Interpreters, Linkers and Loaders.
MEMORY:Computer accepts data through various input devices. The control unit controls its entire operation including its input and output devices. After the data is received it is processed by ALU by applying various numeric and logical operations on it according to the commands.
Computer’s memory is a physical device, It helps to store data and information in form of bits and bytes, for processing and future retrieval. The data and programs that are in use are stored temporarily or permanently in the memory as per the need and type of memory used.
Computers process information stored in their memory, which consists of data storage units.
We can categorize the memory as follows:
1.Primary/Main memory/Semiconductor
memory: These have small storage
capacity, cost of storage per bit is higher and have faster access time. Here
access time means the time taken by the CPU to access a particular location in
the memory. Example RAM, ROM.
There are mainly two types of semiconductor memory: random-access memory (RAM) and read-only memory (ROM).
2.Secondary/Auxiliary memory/Magnetic memory/Optical memory:
This kind of memory has a larger storage capacity used for long time storage of data, and programmers which need higher capacity of storage such as multimedia files. The cost of storage per bit is low and the access time is medium.
Most commonly used secondary storage is the hard disk.
When data from the secondary storage devices is to be processed, it has to be shifted first to the main memory as CPU cannot access these devices directly. As we see that we need a larger sized storage device to store a big amount of content. But it increases the access time. To overcome this disadvantage, cache memory can be used in between the CPU and the main memory. Cache memory increases the speed of processing as it makes data available for the CPU to read at a higher speed rate.
RAM(RANDOM ACCESS MEMORY):
RAM is a temporary data storage domain,It is also called volatile memory because it cannot hold the data even after the computer is switched off.
There are mainly two types of RAM: one is DRAM (dynamic RAM), and the other is SRAM (static RAM).
DRAM stores information in capacitors and since the capacitors slowly discharge, the information fades away unless the capacitor charge is refreshed periodically. In practice, the data on DRAM need to be read and rewritten (i.e., refreshed) dozens of times per second.
In contrast, SRAM needs no refreshing because it uses flip-flop circuits* to preserve the data. SRAM is more expensive than DRAM because of the complex circuitry involved, but is also faster.
ROM(READ ONLY MEMORY):
Read-only memory (ROM) is used for retrieving stored data that are permanently fixed and cannot be rewritten. Many home appliances such as washing machines and rice cookers use ROM devices to store pre-set
whereas ROM serves as a semi-permanent storage domain. It is also called non-volatile memory because it can hold the data even after the computer is switched off.
Secondary Storage: Hard Disk Drives (HDD) & Solid-State
Drives (SSD)
In addition to RAM, every computer also has another storage drive that’s used for storing information on a long-term basis, and this is known as secondary storage.
There are two types of storage device used
as secondary storage in computers: HDD and SSD. While HDDs are the more traditional of the two, SSDs
are fast overtaking HDD as the preferred tech for secondary storage.
Secondary storage devices are often removable, so you can replace or upgrade your computer’s storage, or move your storage drive to a different computer
. 
External
HDDs and SSDs:
You can get both
HDD and SSD devices as external drives. These generally offer the largest
storage capacity among external options, with external HDDs offering up to 20
TB of storage and (reasonably-priced) external SSDs offering up to 8 TB of
storage.
Flash
memory devices:
A flash memory device
contains trillions of interconnected flash memory cells that store data. These
cells hold millions of transistors that when switched on or off represent 1s
and 0s in binary code, allowing a computer to read and write information based
on the electrical current of the transistors.
Optical Storage Devices:
CDs, DVDs, and Blue-Ray disks are used for a lot more than just playing music and videos—they also act as storage devices, and collectively they’re known as optical storage devices or optical disk media.
Floppy Disks
Floppy disks were the first widely-available portable, removable storage devices. They work in the same way as hard disk drives, although at a much smaller scale.
Input /Output Ports
A connection point that acts as interface between the computer and external devices like mouse, printer, modem, etc. is called port. Ports are of two types −
Internal port − It connects the motherboard to internal devices like hard disk drive, CD drive, internal modem, etc.
External port − It connects the motherboard to external devices like modem, mouse, printer, flash drives, etc.
Let us look at some of the most commonly used ports...
Serial Port
Serial ports transmit data sequentially one bit at a time. So they need only one wire to transmit 8 bits. However it also makes them slower. Serial ports are usually 9-pin or 25-pin male connectors.
Parallel Port
Parallel ports can send or receive 8 bits or 1 byte at a time. Parallel ports come in form of 25-pin female pins and are used to connect printer, scanner, external hard disk drive, etc.
USB Port
USB stands for Universal Serial Bus. It is the industry standard for short distance digital data connection. USB port is a standardized port to connect a variety of devices like printer, camera, keyboard, speaker, etc.
PS-2 Port
PS/2 stands for Personal System/2. It is a female 6-pin port standard that connects to the male mini-DIN cable. PS/2 was introduced by IBM to connect mouse and keyboard to personal computers.
Infrared Port
Infrared port is a port that enables wireless exchange of data within a radius of 10m. Two devices that have infrared ports are placed facing each other so that beams of infrared lights can be used to share data.
Bluetooth Port
Bluetooth is a telecommunication specification that facilitates wireless connection between phones, computers and other digital devices over short range wireless connection. Bluetooth port enables synchronization between Bluetooth-enabled devices. There are two types of Bluetooth ports −
Incoming − It is used to receive connection from Bluetooth devices.
Outgoing − It is used to request connection to other Bluetooth devices.
Compilers,Interpreters, Assemblers
Interpreter:
An interpreter is a computer program, which coverts each high-level program statement into the machine code. This includes source code, pre-compiled code, and scripts. Both compiler and interpreters do the same job which is converting higher level programming language to machine code. However, a compiler will convert the code into machine code (create an exe) before program run. Interpreters convert code into machine code when the program is run.
Linkers and Loaders
In execution of the program, major role is played by two utility programs known as Linker and Loader.
2. Loader:
The loader is special program that takes input of object code from linker, loads it to main memory, and prepares this code for execution by computer. Loader allocates memory space to program.
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