How Pen drive works

Everyone of us today carrying a pen drive in our pockets as a compulsory gadget, as in previous days we used to carry a small pocket book. But, we are unaware of how a pen drive works and stores such a large data, as such 32GB of storage on a single chip. Let me discuss the "internal architecture of a pen drive" in a lucid style.

A pen drive consists of memory elements. A memory element is an electronic device, normally a flip-flop. A flip-flop is combinational circuit, having a group of basic logic gates.

A logic gate is a combination of transistors or diodes or a combination of both. The out put of logic gate is in the form of voltage. Presence of voltage upto a certain level, say 5 volt (it is decided by the manufacturer) is treated as ON condition and denoted by '1' (one). Similarly, the absence of voltage or voltage level less than the 5 volt is treated as OFF condition and denoted by '0' (zero). These ones and zeroes are called as binary digits (Bit). Examples of logic gates: OR, AND, NOT, XOR etc.

A flip-flop is combination of logic gates. It is also called as a memory element. It stores data in the form of binary digits. Each flip-flop is capable of storing only one bit. A group of 4 flip-flops together stores 4-bit number. A 4-bit number can represent 16 different data, it is calculated by using the formula 2*2*2*2=16 i.e., 2 multiplied 4 times. Here we use 2 because a binary number system contains only 2 digits. Similarly, a group of 8*10^9 flip-flops can store 1GB of data, in other words 8,000 Millions of flip-flops have a capacity of 1GB data storage.

A group of 8,000 Million flip-flops are embedded on a single Silicon Chip to form 1GB pen drive. Similarly, you can calculate how many flip-flops to be embedded on a single chip to form a desired capacity of pen drive by using (8000 Million)*(number of GB required).

This is the internal architecture of a pen drive.