When I say memories, your mind probably goes to childhood, marriages, births, vacations, etc. Fond or maybe traumatic events that have imprinted themselves into our minds for better or for worse.

Today is Memorial Day in the United States. A federal holiday for remembering the people who died while serving in the country’s armed forces. The holiday originated as Decoration Day after the American Civil War in 1868, when the Grand Army of the Republic established it as a time for the nation to decorate the graves of the Union war dead with flowers. Memorial Day eventually extended to honor all Americans who died while in military service.

Or if you are my mother, to place flowers on the graves of every deceased relative she can find – military service or not.

But the memory that has my focus today is in the brain of a computer. Computer memory is any physical device capable of storing information temporarily or permanently. Most common is the Random Access Memory (RAM) – a volatile memory that stores information on an integrated circuit used by the operating system, software, and hardware.

Memory is just like a human brain. It is used to store data and instructions. The memory is divided into large number of small parts called cells. Each location or cell has a unique address, which varies from zero to memory size minus one. For example, if the computer has 64k words, then this memory unit has 64 * 1024 = 65536 memory locations. The address of these locations varies from 0 to 65535.

Memory is primarily of three types:

  • Cache Memory is a very high speed semiconductor memory which can speed up the CPU. It acts as a buffer between the CPU and the main memory.
  • Primary Memory/Main Memory holds only those data and instructions on which the computer is currently working. It has a limited capacity and data is lost when power is switched off.
  • Secondary Memory is also known as external memory or non-volatile. It is slower than the main memory. These are used for storing data/information permanently.

In humans, semantic memory refers to a portion of long-term memory that processes ideas and concepts that are not drawn from personal experience. Semantic memory includes things that are common knowledge, such as the names of colors, the sounds of letters, the capitals of countries and other basic facts acquired over a lifetime.

In technology, a semantic network is a knowledge base that represents semantic relations between concepts in a network. This is often used as a form of knowledge representation. It is a directed or undirected graph consisting of vertices, which represent concepts, and edges, which represent semantic relations between concepts, mapping or connecting semantic fields. Semantic networks are in use in various natural language processing applications.

In some ways, human memory and computer memory are similar. For example, some general characteristics of human short-term memory resemble those of a computer’s RAM. Human short-term memory is volatile and has a limited capacity. Computer RAM has essentially the same characteristics. Your computer often does not have enough memory to run certain programs, and when you turn it off, the data is lost.

Your long-term memory is something like a computer’s hard drive. Both of them take longer to respond, but can store a considerable quantity of data.

But this latter analogy falls apart when you compare the ways that a computer and your own brain store information. Once pieces of information are recorded on a computer’s hard drive, they will not change one bit over the years. But your own memories are totally different. Over the years, they will be continuously altered and reconstructed in response to changes in your moods or always changing cognitive states of mind.

Melody K. Smith

Sponsored by Access Innovations, the world leader in thesaurus, ontology, and taxonomy creation and metadata application.