What is computer memory?
Computer memory is used to store data and programs either temporarily or permanently within a electronic computer. All computers store and interpret data in binary format which is a series of 1s and 0s. A binary bit can be retained in a system which is one of two stable states representing 1 and 0. This is called a bistable system. It could be a capacitor that can lose charge or store, the polarity of a magnet or just a simple on and off switch. In the computing world today, transistors and capacitors that function as switches are typically used to temp storage, magnetic coated tapes and disks or disc made from plastic with a pattern of pits that are used for storage.
Today's computer memory implements the use of integrated circuits that have transistors made from silicon. The two main types of memory at the very top level are volatile and non volatile memory.
Some history on memory technology
Memory technology has been around since the early 1940s when the technology could hold a maximum of a few bytes. The ENIAC which is the very first digital computer, used a 20,000 octal base radio vacuum made up of tubes. It was able to make simple calculations that invloved twenty numbers of 10 decimal digits, these were held in the vacuum tubes.
Later the next major advancement in computer memory technology while still in the early 1940s was acoustic delay line memory which was made by J. presper eckert. It was a glass tube filled with a certain amount of mercury and at each end would be a quartz crystal. Bits of information could be stored within the quartz and would be transferred via sound waves propagating through the mercury. This was known as delay line memory and it was limited to just a few hundred bits.
Later alternatives to delay line memory appeared in 1946, one was the selectron tube and the other was the williams tube. Both of these developments used electron beams within tubes made from glass. The williams tube used cathode ray tubes and was the first type of random access memory. Also the williams tube was able to hold a greater amount of information than the selectron tube. The selectron limited to just 256 bits and the williams being able to hold thousands plus and was also cheaper too.
Even later in the 1940s, Jan A. Rajchman, Jay Forrester and An Wang developed a type of non volatile memory called magnetic core memory. It allowed for the recall of memory after power was lost. This type of memory was dominating the market until transistor based memory was introduced in the 1960s.
What is volatile memory?
Volatile memory is a type of memory that needs constant power to hold the information it has stored within memory. The current volatile memory industry consists of semiconductor technology which is either SRAM also known as static ram and DRAM which is known as dynamic ram. Static ram is able to retain data but all data is lost if there is no power. And dynamic ram allows the data to disapear without refresh, which makes it very fast. Other memory technologies that have been development or are being developed to compete or replace the main two types of memory are A-Ram, TTRam and Z-Ram.
What is non volatile memory?
This type of memory can keep data stored, even when there is no power. Some examples of non volatile memory are flash drives, hard drives, read only memory, floppy discs, optical discs and magnetic tape.
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