Random Access Memory (Ram)

In: Science

Submitted By haswid
Words 2020
Pages 9
Random access memory
• Sequential circuits all depend upon the presence of memory. – A flip-flop can store one bit of information. – A register can store a single “word,” typically 32-64 bits. • Random access memory, or RAM, allows us to store even larger amounts of data. Today we’ll see: – The basic interface to memory. – How you can implement static RAM chips hierarchically. This is the last piece we need to put together a computer!

Random Access Memory


Introduction to RAM
• Random-access memory, or RAM, provides large quantities of temporary • storage in a computer system. Remember the basic capabilities of a memory: – It should be able to store a value. – You should be able to read the value that was saved. – You should be able to change the stored value. A RAM is similar, except that it can store many values. – An address will specify which memory value we’re interested in. – Each value can be a multiple-bit word (e.g., 32 bits). We’ll refine the memory properties as follows: A RAM should be able to: - Store many words, one per address - Read the word that was saved at a particular address - Change the word that’s saved at a particular address

• •

Random Access Memory


Picture of memory
• You can think of computer memory as being one big array of data. – The address serves as an array index. – Each address refers to one word of data. You can read or modify the data at any given memory address, just like you can read or modify the contents of an array at any given index. If you’ve worked with pointers in C or C++, then you’ve already worked with memory addresses.

Random Access Memory


Block diagram of RAM
2k x n memory k n




• This block diagram introduces the main interface to RAM. – A Chip Select, CS, enables or disables the RAM. – ADRS specifies…...

Similar Documents

Virtual Memory

...head: THE BENEFITS AND USES OF VIRTUAL MEMORY The Use and Benefits of Virtual Memory Jacqueline Askew University of Phoenix Abstract There are many computer users that are not familiar with computers or the way they function. This paper is centered around and will provide a definition of virtual memory. Information will also be provided on the benefits and how virtual memory used. The Use and Benefits of Virtual Memory There are so many facets to computers and how they function. Someone that is a novice user is not aware of how they run. They just turn them on and ready, set go. The more advanced computer user has a better insight to the functionality and maintenance of the computer. Whether it is a laptop or desktop the most common part of an operating system is virtual memory. Based on how much memory a computer has determines how many programs can be run. Virtual memory uses free space found on the hard drive in order to allow other programs to run. This seamless transition is unnoticeable to the human eye. Because the virtual memory frees up space in the Random Access Memory, other applications can load. This is an automatic process, so even with the standard memory virtual memory makes it seems like it has more. One of the benefits of virtual memory is the financial side. There is not a lot of out of pocket expense because it becomes more expensive to purchase RAM chips than hard disk space. The virtual memory will allow a user to run......

Words: 472 - Pages: 2

Memory White Paper

...White Paper on Memory Usage 6/19/2008 Abstract: This paper was written to compare customer environments with regards to memory usage for the Interactive Application running on Metaframe servers in the Hosting environment. Data Information: A sample group of servers was chosen at random and the following information was obtained from these servers using two methods. Calculations were made from the both groupings of data, each section will show the calculation methods used. As a best practice on physical machines memory utilization should not exceed 90%. The remaining 10% of unused memory is to manage runaway processes, unexpected errors, less utilization of memory paging swap file, and memory available to avoid a system abort. 1. HP OpenView data collection occurred on 6/17/2008 a. Physical Memory as reported by HP OpenView b. Max Memory used at time of sample c. Memory (MB)Avail from Peak d. 90% of available memory for process use e. Total users at time of sample 2. Hyena System Reporting data collection occurred on 6/23/2008 a. System Processes and memory utilization for each b. Application process requirements for and c. Total memory used for system and application processes d. Total users at time of sample 3. Calculations a. Total memory available after 90% ruled applied b. Total memory available after 90% rule applied with system and......

Words: 1897 - Pages: 8

Memory Access

...Direct memory access Anthony Ou 355 3/5/2013 Castle Phelps Direct Memory Access Should DMA access to main memory be given higher priority than processor access to main memory? I believe the direct memory access should have the main priority access to main memory over the processor. Direct memory access is feature of computer hardware that allows devices to gain access to the main bus linking the processor to the system memory. Direct memory access moves data directly between the main memories or to another part of the system independently. Direct memory access can transfers memory a lot quicker than the processor itself. The processor must wait for the peripheral to respond in order to transfer any byte or words while the direct memory access directly has access and communicate with the peripheral to transfer the data. * What is the purpose and technique of DMA logic? Direct memory access allows some of the hardware sub-systems to access system memory independently of its CPU. Without direct memory access, when the CPU is using input/output programs, it is typically occupied by the full duration of the read or write operation, and it cannot perform other work. With direct memory access, the CPU can initiates the transfer and does other operations while the transfer is in progress, and will be interrupted by the controller of the direct memory access when the operation is completed. Direct memory access is useful when the CPU could not keep up with the data......

Words: 378 - Pages: 2

The Benefits and Uses of Virtual Memory

...The Benefits and Uses of Virtual Memory Marcia Amnay POS/355 Steven Kernan April 22nd, 2013 The Benefits and Uses of Virtual Memory This paper will discuss the benefits and uses of virtual memory. Programs require memory to start and run on computers. When several jobs are being processed at the same time, the operating system must keep track of how the computer’s memory and make sure there is enough. Computers come with a limited amount of random access memory which is known as RAM. RAM is the main memory on a computer. If a user is running multiple applications at the same time, the RAM on it will not be enough to execute the processes. This is when virtual memory comes in and balances the process. Virtual memory is a memory management technique. Virtual memory is secondary memory that can act as if it were part of the main memory. When the RAM is used up, virtual memory places data by using the hard disk or another disk of some kind for space. The hard disk is much slower then RAM so the more virtual memory used, the slower your computer will run. The computer will look for areas on the RAM that are not in use and copy it to the hard disk to free up space on the RAM. Virtual memory keeps ‘active’ process in the RAM and keeps the ‘inactive’ processes on the address space on the disk. When an ‘inactive’ process is needed, it will bring that process back to the RAM from the disk. This process is running in the background without the user being......

Words: 788 - Pages: 4

Ram Basic Study Sheet

...Ram Basics – is used for programs and data, and by the operating system for disk caching( using ram to hold recently accessed disk sectors). Ram types – (RAM) RANDOM ACCSSES MEMORY DRAM – Dynamic-RAM requires frequent charges of memory to retain its content or dose need to be refreshed. SRAM – Static-RAM does not need to be refreshed. SDRAM- Synchronous Dynamic-RAM, was first to run in sync with the processor bus DDR SDRAM – Double Data Rate , performs two transfers per clock cycle rather than one as in regular SDRAM. RDRAM -RAMBUS DIRECT RAM also known as RIMMs ATA Specs – A series of standards for ATA/IDE and SATA drives are referred to as ATA specs. PIO stands for Programed Input Output and UDMA stands for Ultra Direct Memory Access. This Is protocol for transmitting data between the hand drive and RAM directly, by passing the CPU. Configuring PATA Bios – consist of hard drive Geometry, Data transfer rate, Logical Block Addressing, the number of sector per track, number read and write track and number cylinders. Understanding Bios and Firmware – Bios I a complex piece of Firmware (“software on a chip”) that provides support for the following features and devises, storage devices connected to the motherboard, configuration of the main cache memory, configuration of built in ports-PATA-SATA-USB-PS/2, hardware monitoring. BIOS also runs POST and is to identify test and initialize components. BIOS updates – is needed when you upgrade hardware and you bios......

Words: 942 - Pages: 4

Computer Memory

...Computer Memory 1.Introduction: Just like humans, computers rely a lot on memory. They need to process and store data, just like we do. However, computers store data in digital format, which means the information can always be called up exactly the way it was stored. computer memory - an electronic memory device; "a memory and the CPU form the central part of a computer to which peripherals are attached" 1.1History of memory: In the early 1940s, memory technology mostly permitted a capacity of a few bytes. The first electronic programmable digital computer, the ENIAC, using thousands of octal-base radio vacuum tubes, could perform simple calculations involving 20 numbers of ten decimal digits which were held in the vacuum tube accumulators. The next significant advance in computer memory came with acoustic delay line memory, developed by J. Presper Eckert in the early 1940s. Through the construction of a glass tube filled with mercury and plugged at each end with a quartz crystal, delay lines could store bits of information within the quartz and transfer it through sound waves propagating through mercury. Delay line memory would be limited to a capacity of up to a few hundred thousand bits to remain efficient. Two alternatives to the delay line, the Williams tube and Selectron tube, originated in 1946, both using electron beams in glass tubes as means of storage. Using cathode ray tubes, Fred Williams would invent the Williams tube, which would be the first......

Words: 3247 - Pages: 13

Memory Management Comparison

...Memory Management Comparison Christopher Liebenrood POS/355 March 24, 2014 Chris Miserendino Memory Management Comparison While researching the differences between the memory management systems of Windows and Linux operating systems there was not many differences except a small few. To start the memory management system is one of the most vital parts of the system. It manages and organizes the structure of (RAM) Random Access Memory as well as the hard disk. The important task it performs includes allocation and deallocation of the memory. This includes the logistics of the operating system and the use or start of virtual memory by using the hard disk as extra RAM. It is important to utilize or optimize the full potential of the systems memory considering it greatly affects the performance and speed of the operating system. So let's start with the Windows Operating System. Windows has two kinds of memory virtual and physical. The memory of this particular operating system is managed with pages and processes demand it as it becomes necessary. Memory pages are 4KB in size for both kinds of memory (Sneath, 2014). Depending on the architecture of the system you may allocate large pages for efficiency (Sneath, 2014). Windows organizes its memory in a tree structure. Every branch of the tree is called a node and they are virtual address descriptors (VAD). The VAD marks a range of address and they have the same security parameters and commit state information. The VAD......

Words: 677 - Pages: 3


...Memory Psy105   The definition of memory is: the mental capacity or faculty of retaining and reviving facts, events, impressions, etc., or of recalling or recognizing previous experiences (Dictionary.com). There are three different types of memory Sensory, Short-Term and Long-Term memory. Sensory memory is memory that is seen by the eye that the mind keeps as a referencing point for a short period of time. This type of memory gives the eye a larger field of view. The eye’s field of vision is actually very small, but sensory memory retains images that he eye has already seen. This type of memory retains this information for a short period of time that way the eye will remember things it has already seen and doesn't have to reprocess all new information every time it sees something in view. The next form of memory is Short-Term memory. This type of memory is also known as primary or active memory. Freud referred to this type of memory as the conscious mind; active memory goes along with sensory memory just taking it to the next step and retaining those same images for a longer period of time. Short term memory is like RAM in a computer. Now short term holds memories for longer than sensory memory, but does not hold it forever there is another type of memory just for long sustained memory. The type of memory that is sustained for a long period of time is referred to as Long Term memory. This type of memory is referred to as the unconscious by Freudian psychology. The...

Words: 679 - Pages: 3

Memory Management

...Memory Management Vicki Zafke POS/355 June 02, 2014 Melba Beavers Memory Management A critically important component of a computer’s operating system is the memory. Memory management is the act of monitoring and handling the memory. An operating systems memory management includes tasks such as relocation, protection, sharing, and organization. Although there are several basic factors in regards to memory management, some operating systems have distinguishing features that set them apart from one another. There are two main tasks that an operating system must achieve during the memory management cycle. Each process has its own memory space. For example, in the 32-bit Windows operating system each process is allotted up to 4 gigabytes of memory in the virtual address space. The first task is to ensure that the process does not run into another processes space and that another process does not run into it. The second task is in order for the process to run effectively, the different types of memory must be used properly. Virtual memory is a common concept for operating systems. “The Windows virtual memory manager controls how memory is allocated and how paging is performed.”(Stallings, 2012, p. 386). Virtual memory is separated into two parts, one for the process and one for the system. For example, the 4 gigabytes in the 32-bit Windows operating system is divided into two so that 2 gigabytes is reserved for the process and 2 gigabytes is reserved for the......

Words: 448 - Pages: 2

W1 - Memory Management Paper.Docx

...systems the software intended to run on either system is not compatible with each operating system. One big and important difference in these two operating systems is the memory management. When speaking of memory within a computer it can be described as RAM (Random Access Memory) and memory such as storage within a hard drive to store the operating system for use. Windows Windows operating systems use a file system called NTFS (New Technology File System). This is a proprietary file system that was developed by Microsoft Corporation. This file system has been around for years and it is still very stable. Being stable is a positive factor about the NTFS, but it also have its negatives. Over a period of time the NTFS stores and moves files to random places and it will eventually start to slow down the hard drive. These files become fragmented and then will need to be defragmented to help clear some space and speed up the hard drive. Windows have a 32-bit and a 64-bit virtual address space. There is a couple key factors that involve memory organization on Windows operating system. A 32-bit operating system can recognize up to 4GB of RAM. A 64-bit operating system can recognize 4GB and above amount of RAM. User space and system space are two separate components. Processes can access only user space. The Virtual Memory Management stores page tables and other data in system space. Windows operating system allows each process to 4GB logical address space by using paging. The......

Words: 485 - Pages: 2

Memory Management

...Memory Management Memory Management The processes share the CPU along with the share of physical memory. I will be discussing the operating system memory requirements. Memory requirements may be demanding and complex, but there are many techniques to help it be more efficient. There are tremendous varieties of computer systems that cause the complexity. These include systems as smart phones, shared systems, supercomputers, and personal computers. Secondly, the accelerated pace of change that has represented computer systems for many years. The variations are not just of the different systems from capacity and speed of the computers; they are in the applications and the system support. Memory management can be split into three areas: hardware memory, operating system, and application memory. Memory Management “Refers to a variety of methods used to store data and programs in memory, keep track of them and reclaim the memory space when they are no longer needed. It also includes virtual memory, bank switching and memory protection techniques,” (The Computer Language Company Inc., 2014). Memory management is crucial for operating systems because of its multi-tasking ability. Switching the memory space in the system, aids from one process to another. Virtual memory stems from memory management as it provides a tool called the loader to load data from the secondary memory to the main memory. There are strong benefits that this method provides, multi-tasking of......

Words: 514 - Pages: 3

Exploiting Memory Access Patterns to Improve Memory Performance in Data-Parallel Architectures

... Lecture critique et synthèse de: Exploiting Memory Access Patterns to Improve Memory Performance in Data-Parallel Architectures Jean-François Patenaude Département de génie logiciel et des technologies de l’information, École de technologie supérieure 1100 rue Notre-Dame Ouest, Montréal (Québec) H3C 1K3 Canada Abstract—On retrouve une quasi-ubiquité de GPU permettant les calculs en tout genre (GPGPU) sur le marché. Or, il y a encore peu de logiciels qui en prennent avantage. Une de ces raisons est la complexité du développement de logiciels parallèles sur les GPU. C’est en grande partie parce que la gestion de la mémoire est laissée aux soins du développeur. D’ailleurs, une mauvaise gestion de la mémoire peut impacter grandement la performance du logiciel, d’autant plus que les cartes graphiques sont optimisées pour offrir une très large bande passante de mémoire, mais avec des temps de réponse moins rapide. Un article portant sur une méthodologie qui permet de systématiser l’application de techniques d’amélioration de l’accès de la mémoire afin de garantir de bonnes performances a récemment été publié. Selon cette méthodologie, l’optimisation est alors fonction des différents patrons d’accès de la mémoire et de l’architecture sous-jacente : vectorielle comme les GPU d’AMD ou scalaire comme ceux de NVIDIA. Dans le présent article, une synthèse de la méthodologie sera présentée. Puis, une analyse suivra afin de discuter de la méthodologie et de la critiquer. Index......

Words: 3534 - Pages: 15

Memory Management Paper

...Memory Management Memory management is an important core part to any operating system. The basic function is to manage the RAM and hard disks on a computer. The tasks include allocating the memory and processes taking care of logistics and implementation of the virtual memory. It does this by utilizing the hard disks memory as more RAM. Optimization of the memory affects the overall performance and speed of the computer system. Windows uses an executive component known as Virtual Memory Manager to manage memory. Windows moves pages from disk to main memory known as prefetching and pagefiles the files that do not fit in the main memory. Windows Xp supports 16 pagefiles on its 32 bit virtual address space along with 4 GB of virtual address space. There is a 64 bit edition that has 64 bit address space. Windows user space is different than the system space, processes can only access user space whereas; the virtual memory manager stores page tables and other data in the system space. Windows dedicates 2 GB for the user space and 2 GB for system space with 4 KB pages. Windows on a positive note uses NTFS, but it is old and yet stable. The downside to this is that it is an outdated file system with an inability to organize files and it requires the user to defragment the OS to fix. Eventually NTFS moves files into random places on the hard drive through defragmentation which will begin to slow down the computer. Linux memory manager supports 32- 64 bit addresses along with......

Words: 641 - Pages: 3

Memory Managment

...Markus Robinson Memory Management James Welti, Jr. POS/355 July 10, 2015 Memory Management And Its Requirements Memory management is the act of managing computer memory at the system level. The essential requirement of memory management is to provide ways to dynamically allocate portions of memory to programs at their request, and free it for reuse when no longer needed. Memory needs to be allocated to ensure a reasonable supply of ready processes to consume available processor time. Memory management also involves subdividing memory to accommodate multiple processes. This process, involving controlling and coordinating computer memory, assigns portions called blocks to various running programs. By doing this the overall system performance is optimized to its maximum performance. Memory management resides in hardware, the operating system, as well as in programs and applications. Within hardware, memory management involves components that physically store data. The components that are involved in memory management include random access memory (RAM) chips, memory caches, and flash-based solid-state drives (SSDs). As users demand change, memory management involves the allocation and ongoing reallocation of specific memory blocks to individual programs in the operating system. By combining two related tasks, known as allocation and recycling, application memory management ensures the availability of adequate memory for the objects and data structures of each running...

Words: 814 - Pages: 4

Ram Function and Form

...How RAM Works 0  Page   1   2   3   4   Computer Hardware Image Gallery MORE ON RAM * RAM Quiz * Does adding RAM make your computer faster? * How to Add RAM to Your Desktop * How to Add RAM to Your Laptop Random access memory (RAM) is the best known form of computer memory. RAM is considered "random access" because you can access any memory cell directly if you know the row and column that intersect at that cell. The opposite of RAM is serial access memory (SAM). SAM stores data as a series of memory cells that can only be accessed sequentially (like a cassette tape). If the data is not in the current location, each memory cell is checked until the needed data is found. SAM works very well for memory buffers, where the data is normally stored in the order in which it will be used (a good example is the texture buffer memory on a video card). RAM data, on the other hand, can be accessed in any order. Similar to a microprocessor, a memory chip is an integrated circuit(IC) made of millions of transistors and capacitors. In the most common form of computer memory, dynamic random access memory (DRAM), a transistor and a capacitor are paired to create amemory cell, which represents a single bit of data. The capacitor holds the bit of information -- a 0 or a 1 (see How Bits and Bytes Work for information on bits). The transistor acts as a switch that lets the control circuitry on the memory chip read the capacitor or change its state. A capacitor is like......

Words: 3957 - Pages: 16