SSD and HDD memory

We chose this invention because today we use much computers and laptops and these memory systems enable saving, storing and reading information. Physics is involved to this because there is magnetism, electromagnetism, mechanical reader, data and electrical signals. There are multiple kinds of storage HDD’s and SDD’s. HDD is slower than SSD memory and it won’t work so many years as the SSD does, but SSD's capacity is lower than HDD's. SSD is used be a storage location for example to Windows operating system.

HDD

Hard Disk Drive (HDD) is based on moving discs (platters) which are coated with magnetic material. HDD's other the most important parts are Actuator and the Slider and magnetic Head. The Actuator includes two strong electromagnets which makes the actuator's arm and head moving that the data is able to be read from the discs. The data is read and saved by the mechanical reader "Head".

The most popular hard disks are usually about 500 GB but generally some laptops could have only 160-320 GB Hard disks.

Picture1. HDD's parts

The data is stored digitally as tiny magnetized bits on the disk. A magnetic orientation in one direction on the disk could represent a "1" and an orientation in the opposite direction could represent a "0".

Picture2. How data is stored in HDD

SSD

Solid State Drives are electronic working of silicon memory chips and it uses NAND based flash memory. There are any moving parts like spinning platters so they are very fast and shock resistant. Inside the SSD are five main parts. These are controller, NAND flash memory, SATA interface, SSD PCB and card (circuit board). The most of the Solid State Drives' capacity are 30/32, 60/64 or 120/128 GB.

Picture3. SSD's parts

NAND Flash Technology of SSD

There are mainly two different NAND Flash types used today, Single-Level Cell (SLC) and Multi-Level Cell (MLC). NAND Flash stores data in a large array of cells. Every cell can store data: 1 bit per cell for SLC NAND and 2 bits for cell for MLC. SLC NAND stores a "0" or "1" in each cell and MLC NAND stores "00", "01", "10" or "11" in each cells. SLC and MLC differences are levels of performance and endurance characteristics at different prices. SLC is higher performing and more expensive than MLC.

Picture4. SDD cards

How is info read from SSD?

The information is travelling from the SSD to the computer through a standard SATA connection. Inside the SSD the controller is an embedded processor that bridges flash memory components to the host (such as a computer).

The controller executes codes provided by the SSD's firmware (a mini operating system) to full-fill the data requests from the host. The information is stored and read with zeros and ones in cells. The memory cells store voltage and (in SLC cells) can be either an on (1) or off (0), which allows them to store data in binary form.

SATA = is a computer bus interface which connects host bus adapters to mass storage devices such as hard disk drives and optical drives.

SSD = Solid State Drive

HDD = Hard Disk Drive