Trends in

MemoryComputing

Changes in memory technology• Once upon a time, computers could not store

very much data.• The first electronic memory storage used

valves (like light bulbs that could be switched on or off). One valve to store one bit.

Large number of valves inthe computer’s memory

Changes in memory technology

• Valves took up a lot of physical space.• They were very fragile.• They got hot very quickly.• If a valve overheated it would pop like a light

bulb. It could not be used to store data anymore. The computer needed to be fixed!

• So computers that used valves for their memory were not very reliable.

Changes in memory technology

• New electronic components were invented that were smaller and more reliable.

• Core memory was still physically large and could not store very much data by today’s standards.

Changes in memory technology• Core memory used a grid of iron rings that could

be magnetised or de-magnetised.• 1 ring is used per bit (binary digit).• When you magnetise a ring it stores a 1, when it

is demagnetised it stores a 0.• You still needed a lot of rings – 1 for every bit that

you store.

Changes in memory technology

• When transistors were invented, these small electronic components were better for making smaller memory circuits that actually had more storage capacity.

• Smaller physical device, that can store more data!

• Silicon chips were a further new development. Thousands or millions of tiny transistors could be stored on one small silicon circuit.

Changes in memory technology

• Modern memory circuits on chips are made up of tiny logic gates.

• One of the gates that is used the most is the NAND (Not-And) gate.

• The smaller the gates are, the more of them can fit in a circuit or on a chip.

• As we have got better at making gates smaller and smaller, the amount of memory that a single chip can hold has got bigger and bigger.

Trends in memory

• Memory devices are getting physically smaller as we get better at making them.

• At the same time, memory devices have a larger capacity – they can actually store more data.

• In 2000, a PC might have had 128 MB of RAM.

• Today, you can buy a typical PC might have 4GB of RAM.

Trends in memory• USB Flash memory drives can store more and

more data – they have higher and higher storage capacity.

• But they are getting physically smaller!128 MB 128 MB 2 GB 2 GB 4 GB 8 GB

20112003

Trends in secondary storage• A hard disk drive made in 1990 was physically

much bigger than a hard disk drive made in 2013.Web link to the evolution of hard disk drives

Old hard disk drive.

Physically big, stores less

data.

Latest hard disk drive.

Physically smaller, stores much more data.

Trends in memory and storage

• The capacity of memory devices is getting larger – they can store more data than they used to.

• A hard disk drive in 1990 might have stored only 250 megabytes.

• Today you can buy a hard drive that will store 2 terabytes (that’s about 8000 times more storage space).

• Storage devices are also getting cheaper.

Trends in memory

• Storage devices are also getting cheaper.• A device that stores the same amount of data

now costs much less than it did 10 years ago.

Quantum MemoryA traditional CPU uses the electronic states of, ‘no charge’ to represent a zero and ‘charged’ to represent a one. Advancements in technology have enabled scientist and engineers to create ‘Quantum computers’.

A quantum computer uses positively charged atoms to represent a one and atoms with no charge to represent a zero. Millions of these states can be written onto the size of a pinhead increasing the overall processing power of the CPU.

The most significant benefit of a Quantum Computer is that these atoms can be either state. They can represent simultaneously both a zero and a one. While current computer perform one calculation at a time, a quantum computer can perform several calculations all at once, in turn considerable increasing the processing speed.

Biological Computing with DNAScientists have engineered human DNA to create a string of ‘0’ and ‘1’, a binary string of data.

Genetic elements and viruses are spliced into DNA, this creates a reaction and this reaction can be interpreted as a either a one or a zero. The process can be revised and overwritten several times using the same strand of DNA. However, the DNA does break down after a while and the data is lost.

Recently UK scientists have encoded an MP3 file, digital photos and 154 of Shakespeare's sonnets into DNA structure.