The main difference between them comes from their speed/cost tradeoffs. Static Random Access Memory (SRAM) This is the faster of the 2, approximately 4 times faster than the DRAM. Since it needs more transistors per bit of data, it is also more expensive compared to DRAMs. DIFFERENCE BETWEEN RAM AND SAM RAM is considered “random access” because access to any memory cell can be done directly if the intersection of row and column is well known. The opposite of RAM is Serial Access Memory (SAM). SAM stores data as a series of memory cells that can only be accessed sequentially. SDRAM - Single data-rate Synchronous Dynamic Random Access Memory - Introduced in 1997, memory access is synchronised to the bus clock and the bus is 64 bits wide. 168 pin modules. Ways in which Data is Stored and Read. In this section we will look at the 2 main ways in which data is accessed, stored and read: Serial Access (also known as 'sequential access) Direct Access (also known as 'random access) Key Concepts of this section: #. Know the difference between 'Serial' and 'Direct' data access.

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Parallel Storage. Data stored on disk is made up of long strings (called tracks and sectors) of ones and zeroes. Disk heads read these strings one bit at a time until the drive.

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Difference Between Serial And Random Access Memory Types Explained

Introduction

Memory recall or retrieval is remembering the information or events that were previously encoded and stored in the brain. Retrieval is the third step in the processing of memory, with first being the encoding of memory and second, being the storage of the memory. Retrieval of the encoded and stored memory is very important because otherwise there is no point in storing information.

During memory recall, there is a replaying of neural activity that was originally generated in the brain during a specific event. This echoes the brain’s perception of that specific event which is not completely identical to that event. In this way, the brain remembers the information and details of the event. Memory recall is not just pulling things from the storage of memories, rather it is a process of creativity in which the relevant information is gathered from the scattered, jigsaw puzzle-like information in the brain.

Memory retrieval requires revisiting the nerve pathways formed during the encoding and storage of the memory. How quickly a memory is retrieved? Well, it depends upon the strength of neural pathways formed during its encoding. According to a theory, memory is stored in three forms: sensory, short-term, and long-term memory. But only information stored in short and long-term memory can be retrieved. However, the exact mechanism of memory retrieval is not completely understood.

Difference Between Serial And Random Access Memory Types Pdf

Types of Memory Recall

There are three main types of memory recall. We will discuss all of them one by one.

Free Recall

In free recall, the person recalls a list of items in any order. There are three types of effects seen in free recall. First, the primacy effect refers to recalling the items presented at the beginning of the list or the items presented more often on the list. Second, the recency effect refers to recalling recent items in the list or the items presented at the end of the list. Third, the cognitive effect refers to the recalling of things successively which are in neighboring positions.

Cued Recall

Cued recall refers to recalling a list of items by using cues and guides. In cued recall, people more often remember the things which they do not remember in free recall. Cues help in retrieval of those memories which are thought to be lost. There is more chance of recalling an item when it has a strong link with the cue. The information can also be presented in the form of pairs of pictures and numbers, and the first thing cues the recall of the second thing in the pair.

Serial Recall

Serial recall refers to the recalling of items or events in the order of their occurrence. In this way, recalling previous item cues to the recall of the next item in the list. It is especially helpful in recalling life events in their chronological order.

There is a difference in serial recall of short-term and long-term memory. It has been seen in different studies that more recently happened events are more easily remembered in order. The memory recall decreases when the items increase on the list. Primacy effect and recency effect are also observed in serial recall.

Two-stage Theory

The two-stage theory explains the process of recalling a memory. According to this theory, the first stage in the process of recall is research and retrieval of information from the storage. The next step is recognition of the correct information from what has been retrieved.

According to some scientists, recognition is superior to recall because it involves only one process while recall involves two processes. So, the recall is susceptible to more errors. But some scientists argue that recall is superior to recognition in some cases. An example of this may include failure to recognize words that can later be recalled.

Encoding Specificity

The encoding specificity theory is more advanced than the two-stage theory. According to this theory, the memory utilizes information both from memory trace or the situation in which it was encoded as well as the situation, context, or environment in which it is retrieved.

It means that if the situation or environment of learning and retrieving is the same, there is more chance of successfully recalling the information. So, if you are a student and you go to the hall where your exams are held every year and study your books in that hall, you will probably score more numbers on the exam.

In the same way, people tend to remember an emotional thing in the mood that matches the emotional memories. For example, a person in a happy mood remembers happy memories.

Forms of Memory Retrieval

Recall

Recall refers to the simple process of remembering something without any cues, and in the physical absence of that thing. The recall is pulling information from the brain. Recalling the name of a person or answering to a question are some examples of recall. In recall, all the neurons involved in the memory are activated and they reconstruct the memory.

Recognition

Recognition is identifying the information of a previously known thing after seeing the thing or experiencing memory again. Recognizing and remembering someone’s name by seeing their picture is an example of recognition. Another example is when you do not remember the location of a restaurant, but you recognize it when you see it.

Recollection

Recollection refers to the rebuilding or piecing together of memory. Our mind reconstructs the memory by utilizing logical structures and clues. Remembering the details of an event using partial memories, clues and logic is a good example of this type of memory retrieval.

Relearning

This type of memory retrieval refers to relearning of the information that has already been learned in the past but is not remembered. People may not be able to recall but they know that they have learned this before. Relearning shows improvement in retrieval of the information as it strengthens the neuronal connections.

Brain Structures Involved in Retrieval

Studies have shown that six areas of the brain are predominantly involved in recall and recognition.

1. The Prefrontal cortex is related to the retrieval attempt.
2. The Hippocampal and Para-Hippocampal areas of MTL are related to conscious recollection.
3. The Anterior cingulate cortex is related to response selection.
4. The Posterior midline area including posterior cingulate is related to imagery.
5. The inferior parietal cortex is related to space awareness.
6. The Cerebellum, especially on the left which is related to self-initiated retrieval.

Increased activity in Globus pallidus, anterior cingulate gyrus, thalamus, and cerebellum is seen during recall. The same activity is not seen in the recognition process which means that these structures play a more important role in recall than recognition. Some studies have shown that recall only takes place when there is synchronic activation of two brain region i.e. rhinal cortex and hippocampus.

According to another study, which included recalling items from a list, huge differences are seen in hemodynamic activity during subsequent recalled and not recalled items. The effect has now been termed as the subsequent memory effect (SME). These differences in activity determine whether a specific item is recalled or not.

Creation of False Memories During Recall

The retrieval process is some time involved in the creation of false memories or wrong interpretation of memories. These false memories result from persistent beliefs, post-event information, wrongly stated and interpreted statements, and interference of new memories with old memories.

According to Elizabeth Loftus, a scientist who researched heavily in this area, the specific or precise wording of a question dramatically changes the recall and recreation of memories which may also lead to permanent changing of existing memories and the creation of false memories. A person’s information on an event is sometimes greatly influenced by a statement or suggestion of an authority figure, this phenomenon is called the misinformation effect.

Hyperthymesia

Hyperthymesia refers to a superior autobiographical memory or an extraordinary ability to recall specific details of life events from the past. The person with this condition can recall the details without practicing any mnemonics or other retrieval strategies.

This is an extremely rare condition and only a few cases have ever been confirmed. One of these cases was a woman from California who was able to recall all the details of his previous life. There was a young English girl who had an amazing photographic memory and an IQ of 191. Some people having this condition say that it is not a gift but a burden for them.

Involuntary Memory Retrieval

Involuntary memory retrieval has been divided into two types: the involuntary autobiographical memory retrieval, and the involuntary semantic memory retrieval.

Involuntary autobiographical memory retrieval refers to automatic reactivation of unconscious memories as a result of any sensory or internal cue, like a thought. Those autobiographical memories that are seemingly not associated with any kind of cues are lost easily. In this case, there is an error that occurs in the self-regulation of memory. As a result, the unrelated autobiographical memory reaches the conscious mind. The specific goals of a person most frequently result in involuntary retrieval of memories related to the goals.

The process of involuntary semantic memory retrieval is the same as involuntary autobiographical memory retrieval. This type is also known as “semantic popping”. This type refers to involuntary retrieval of a random word, image, or concept. Though the process is similar to IAM retrieval, there is no personal grounding in ISM retrieval.

Tip-of-the-tongue

This phenomenon refers to the failure to recall a word from memory which is combined with the feeling that retrieval is imminent. There may be a partial recall in this case. There is a perception of a wide gap between the knowledge of a specific word or subject and being able to retrieve the names involving said subject or the word. People sometimes recall other features of the target word such as its first letter or the words that have a similar meaning.

Two theories have been given by scientists to explain this phenomenon. The first is the direct-access perspective, according to which the memory is not strong enough to recall but it is strong enough to trigger the partial recall. The second is the inferential perspective which states that the state of partial recall occurs when the subject can infer knowledge of the target word, but not able to join the pieces of information together usually because those pieces do not exist in the memory.

Factors Affecting Retrieval

Context

The characteristics of the environment in which a memory is encoded are also encoded along with the memory. This leads to the context-dependency of retrieval which means that the memories are more easily retrieved in the same environmental conditions in which they were encoded.

Gender

Studies have shown that females are better than males at recalling episodic memories, but no differences have been seen in the two during retrieval of semantic memories. The gender differences in memory retrieval are the result of using different strategies for processing information. A study has shown that females remember non-verbal cues while males tend to remember verbal cues.

Attention

Attention has an effect on memory in its encoding process. If someone does not focus on something in the encoding phase, it is very difficult for that person to retrieve it later.

Interference

Interference refers to the interaction between previous memories and newly formed memories. Proactive interference is the forgetting of new memories due to their interference with old memories in the brain. Retroactive interference is a failure to recall previously encoded information due to its interaction with new knowledge.

Physical Activity

Physical activity or physical health appears to be an important factor in the retrieval of memories. Children with poor physical health usually have poor mental and cognitive health. Low physical activity and fitness level is directly linked to low academic achievement due to mental and cognitive problems.

Studies have shown that physical activity plays an important role in influencing the hippocampus. The hippocampus is the part of the brain involved in the encoding of information. It may also affect other areas of the brain. In this way, physical activity and exercise help in the proper functioning of the neural networks.

Food Consumption

Some studies have shown that eating breakfast before going to school helps in more retrieval of information. The students who have a habit of eating breakfast generally scored more in their exams.

Retrieval Failure

Retrieval failure refers to the failure to recall information from long-term memory. In this case, memory has been previously encoded in long-term memory, but the person is not able to retrieve it. This does not happen due to the loss of the memory but because there are no cues available to retrieve it. Retrieval cues are of two types. External cues or contextual cues which are in the environment and Internal cues which are inside the human brain.

In these cases, mostly the environment in which memory is being retrieved is different from the environment of its encoding. Hence there are no external cues present which then leads to retrieval failure of the memory. For example, sometimes a person cannot remember the details of an event but returning to the place of that event gives him external cues and he begins to remember the details.

Summary

Memory recall and retrieval involve remembering different types of memories stored in the brain. One can experience the memories by the process of memory retrieval or recall.

The speed of memory retrieval and recall depends on the strength of neural pathways formed in the earlier stages of memory processing.

Memory recall is divided into three types;

• Free recall in which memories are recalled in a list order
• Cued recall where different hints are used for recalling memories
• Serial recall when memories are recalled in a sequence of their occurrence

According to the two-stage theory, memory recall first includes the retrieval of information from the storage site and later involves checking the authenticity of the retrieved information.

Encoding specificity is an advanced theory that explains memory retrieval in accordance with the context and situation in which memory was encoded and is being retrieved.

Different types of memory retrieval include recall, recognition, recollection, and relearning.

Many areas of the brain are involved in memory retrieval such as the prefrontal cortex, areas of the temporal lobe, cerebellum, etc.

Some evidence does exist about the formation of false memories during the recall process.

Hyperthymesia is a phenomenon that refers to an extraordinary ability to remember minor details of events in a man’s life.

Involuntary memory retrieval is also seen in humans that involve both autobiographical and semantic memories.

The memory retrieval process can be affected by several factors such as the context of the event, food consumption, physical activities, etc.

Retrieval failure is also seen in some people due to certain reasons.

References

Difference Between Serial And Random Access Memory Types Used

1. Botvinick, M.; Wang, J.; Cowan, E.; Roy, S.; Bastianen, C.; Mayo, P.J.; Houk, J.C. (2009). 'An analysis of immediate serial recall performance in a macaque'. Animal Cognition. 12 (5): 671–678. doi:10.1007/s10071-009-0226-z. PMID19462189.
2. Watkins, M.; Gardiner, J. M. (1979). 'An appreciation of the generate-recognize theory of recall'. Journal of Verbal Learning and Verbal Behavior. 18 (6): 687–704. doi:10.1016/s0022-5371(79)90397-9.
3. Tulving, E.; Thomson, M. (1973). 'Encoding specificity and retrieval processes in episodic memory'. Psychological Review. 80 (5): 352–373. doi:10.1037/h0020071.
4. Tarnow, E. (2015). FIRST DIRECT EVIDENCE OF TWO STAGES IN FREE RECALL. RUDN Journal of Psychology and Pedagogics, (4), 15-26.
5. Bower, Gordon H. (2000). A Brief History of Memory Research. The Oxford Handbook of Memory. (3)
6. Ebbinghaus, Hermann. (1885). On Memory (H.A Ruger & C.E Bussenius, Trans.) New York: Dover, 1964.
7. Endel Tulving. (1972). 'Episodic and Semantic Memory' in Organization of memory, (381-403), Retrieved from http://alicekim.ca/EMSM72.pdf.
8. Paivio, Allan. (1969). Mental Imagery in Associative Learning and Memory. Psychological Review 76, (241-263), Retrieved from http://psycnet.apa.org/journals/rev/76/3/241/.
9. Carrier, Mark; Pashler Harold (Nov 1992). 'The Influence of Retrieval on Retention'. Memory and Cognition. 20 (6): 633–642. doi:10.3758/BF03202713. PMID1435266

Image sources:

1. https://commons.wikimedia.org/wiki/File:Human_visual_pathway.svg
2. https://commons.wikimedia.org/wiki/File:Blausen_0115_BrainStructures.png

When a computer is powered up, a number of processes occur. Specific programs begin to run. The data and instructions necessary for executing the programs are temporarily stored in the computer memory. For most people memory and RAM mean the same thing. However, they are relatively different as you’ll discover in this article.

Definitions

Memory is a generic term referring to the components and devices that the computer uses to store data and instructions. It’s subdivided into cache memory, primary memory and secondary memory. Cache memory is high speed memory that’s installed on the motherboard. It’s fixed in nature. Primary memory is divided into ROM (read only memory), and RAM (random access memory). It’s here that data and instructions needed to execute a program are stored. Secondary memory is used to store data and information permanently and includes the hard disk.

Comparison Chart

Ram vs Memory

What is the difference between Ram and Memory? Let’s take a look at them closely in terms of their type, purpose, speed, and extendibility.

• RAM is a high speed form of primary storage. It’s here that the data and instructions of a currently executing program are stored. Memory on the other hand is a generic term used to refer to all devices and components installed in a computer for storing data and instructions.
• RAM is volatile. That is, it only stores data and instructions temporarily when the computer is on. If a program isn’t executing, data and instructions that relate to it aren’t stored in the RAM. Memory on the other hand can be temporary (cache and primary memory) or permanent (secondary memory).
• RAM is fast. Effective program execution depends on the RAM speed. This ensures speedy access of data for processing by the computer processor. With regard to memory, cache and primary memory are fast. Secondary memory is relatively slow.
• RAM can be extended using high capacity chips. Memory can also be extended. However, extending cache and primary memory is a bit expensive compared to extending secondary memory.