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| | Virtual memory - Wikipedia, the free encyclopedia |
 | | Virtual memory or virtual memory addressing is a memory management technique, used by multitasking computer operating systems wherein non-contiguous memory is presented to a software application (aka process) as contiguous memory. | | | The term "virtual memory" is often confused with "memory swapping" (or "page/swap file" use), probably due in part to the prolific Microsoft Windows family of operating systems referring to the enabling/disabling of memory swapping as virtual memory. | | | The modern solution is to use virtual memory, in which a combination of special hardware and operating system software makes use of both kinds of memory to make it look as if the computer has a much larger main memory than it actually does and to lay that space out differently at will. |
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http://en.wikipedia.org/wiki/Virtual_memory
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| | 1.2.2 Main Memory |
| | Memory in present day computers is usually organized as a sequence of bytes (a byte is a group of eight bits). | | | The maximum number of bytes directly addressable in a computer depends on the number of bits in the memory address. | | | Like other information in the computer, an address is represented internally in binary. |
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http://www-ee.eng.hawaii.edu/Courses/EE150/Book/chap1/subsection2.1.2.2.html
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| | Inside memory management |
| | Memory as a Programming Concept in C and C++ by Frantisek Franek discusses techniques and tools for developing effective memory use and gives the role of memory-related errors the prominence it deserves in computer programming. | | | Memory management is one of the most fundamental areas of computer programming. | | | When allocating memory, in a worst-case scenario it will have to walk across all of a process's memory; this may include a lot of memory located on disk as well, which means the operating system will have to spend time moving data to and from the disk. |
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http://www-128.ibm.com/developerworks/linux/library/l-memory
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| | Memory-Mapped I/O |
| | Memory performs a read or a write, and places result on data bus or copies from the data bus to memory. | | | However, if you have a byte of at some memory address that is really the status of a printer, then the printer is updating that byte. | | | However, instead of having memory at that address, you have an I/O device. |
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http://www.cs.umd.edu/class/spring2003/cmsc311/Notes/IO/mapped.html
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| | Introduction to Protected-Mode |
| | Instead of serving as a physical address, an application-generated address is used by the processor to index one of its look-up tables. | | | Since 1MB of memory was considered an overkill for a personal computer, IBM decided to utilize only the first 640KB for RAM and reserve the remaining 384KB for the BIOS and ISA add-on cards. | | | Any illegal memory reference made by the developed application can be blocked and analyzed by a debugger while ensuring the stability of all other software development tools. |
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http://www.internals.com/articles/protmode/introduction.htm
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| | Memory Address Decoding |
| | The system is halted if an error is found in memory. | | | It has 10 fixed inputs (Pins 1-9, 11), two fixed outputs (Pins 12 and 19) and 6 pins that can be either (Pins 13-18). | | | AND/NOR device with logic expressions (outputs) with up to 16 ANDed inputs and 7 ORed product terms. |
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http://www.csee.umbc.edu/~plusquel/310/slides/8086_memory2.html
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| | Physical Address Extension - PAE Memory and Windows |
| | PAE is an Intel-provided memory address extension that enables support of greater than 4 GB of physical memory for most 32-bit (IA-32) Intel Pentium Pro and later platforms. | | | Although support for PAE memory is typically associated with support for more than 4 GB of RAM, PAE can be enabled on Windows XP SP2, Windows Server 2003, and later 32-bit versions of Windows to support hardware enforced Data Execution Prevention (DEP). | | | Requirements for Large Memory capabilities are defined in Microsoft Windows Logo Program System and Device Requirements. |
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http://www.microsoft.com/whdc/system/platform/server/PAE/PAEdrv.mspx
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| | CS 537 - Memory Management |
| | Since in modern computers, the speed of memory is often the bottleneck (processors are getting so fast that they spend much of their time waiting for memory), virtual memory could make programs run twice as slowly as they would without it. | | | In this case, memory is over-committed and it is hopeless to run all the processes efficiently. | | | Unfortunately, this approach requires a list operation on every single memory reference, and even though it is a pretty simple list operation, doing it on every reference is completely out of the question, even if it were done in hardware. |
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http://www.cs.wisc.edu/~solomon/cs537/paging.html
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| | OSD: Virtual memory |
| | The task virtual memory is private to each task; the identity-mapped and kernel virtual memory are shared among all tasks. | | | Since memory fragmentation is not an issue for these, they may be stored in identity-mapped memory or kernel virtual memory, whichever is more convenient. | | | This means the virtual addresses generated by a program are different from the physical addresses that go onto the address bus; to the memory chips. |
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http://my.execpc.com/CE/AC/geezer/osd/mem
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| | Virtual Memory Address Translation |
| | In a virtual memory system, the program memory is divided into fixed sized pages and allocated in fixed sized physical memory frames. | | | For every memory access, either to fetch an instruction or data, the CPU must translate the virtual address to a real physical address. | | | A dirty bit is set whenever the page is changed to inform the operating system that the page in memory is different than the page on disk. |
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http://williams.comp.ncat.edu/addrtrans.htm
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| | Memory Management Unit from FOLDOC |
| | Some memory management architectures allow each process to have its own area or configuration of the page table, with a mechanism to switch between different mappings on a process switch. | | | A PTE may also include information about whether the page has been written to, when it was last used (for a least recently used replacement algorithm), what kind of processes (user mode, supervisor mode) may read and write it, and whether it should be cached. | | | In a multitasking system all processes compete for the use of memory and of the MMU. |
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http://www.instantweb.com/foldoc/foldoc.cgi?MMU
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| | Memory Access and Access Time |
| | In order to understand how memory is accessed, it is first necessary to have a basic understanding of how memory chips are addressed. | | | Of course, a PC doesn't have a single memory chip; most have dozens, depending on total memory capacity and the size of DRAMs being used. | | | However, in practice, memory chips do not have this many address lines. |
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http://www.pcguide.com/ref/ram/timingAccess-c.html
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| | Feature: High Memory In The Linux Kernel |
| | The mapping of virtual addresses to physical addresses is pretty arbitrary (with a granularity of 4k on x86). | | | The author is suggesting that the part of each process' virtual address space reserved for the Linux Kernel is the upper 1GB, and this is mapped (presumably for all processes) to the bottom 1GB of physical memory. | | | It makes implementing a 'physical memory file' device driver very easy, I would think, provided you are only interested in the bottom 1GB of the physical memory. |
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http://www.kerneltrap.org/node/view/2450
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| | Memtest86 - Memory Diagnostic Page |
| | For proper operation all of memory needs to function properly regardless of what the eventual use is. For this reason Memtest86 has been designed to test as much memory as is possible. | | | Memory is initialized with shifting patterns that are inverted every 8 bytes. | | | Often the memory works in a different system or the vendor insists that it is good. |
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http://www.memtest86.com
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| | How memory works |
| | All the new computer specifications are for sequential memory operations; more of a serial memory interface in a way than what is traditionally thought of as RAM. | | | When a memory location is written to, a hardware parity generator generates a parity bit that is stored in an extra memory chip. | | | The memory in your computer is called RAM (Random Access Memory). |
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http://www.xtronics.com/memory/how_memory-works.htm
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| | Memory Support and Windows Operating Systems |
| | PAE is an Intel-provided memory address extension that enables support of up to 64 GB of physical memory for applications running on most 32-bit (IA-32) Intel Pentium Pro and later platforms. | | | The maximum amount of memory that can be supported on Windows XP Professional and Windows Server 2003 is also 4 GB. | | | This capability allows memory-intensive applications to utilize up to 50 percent more virtual memory on Intel-based computers. |
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http://www.microsoft.com/whdc/system/platform/server/PAE/PAEmem.mspx
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| | memory address - MSDN |
| | In.NET you typically do not need to worry about allocating memory, it is done under hood when you create an instance of an object. | | | im trying to simulate the memory management so i want first to allocate x bytes and then working inside that space only.. | | | Objects created in C# (Assuming you are not using Unsafe Code) are placed in the Managed Heap, It has no permanent memory address coz it is constantly being moved by the GC(Garbage Collector)... |
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http://forums.microsoft.com/msdn/ShowPost.aspx?PostID=3763
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| | How to avoid memory Corruption |
| | A corresponding result can be expected when attempting to decrement a pointer that contains an address of 0, except the result will be 64K instead of 0. | | | Any attempt to increment a near pointer that has a value of 64K (0xffff) will result in a value of 0. | | | int *foo) the compiler will allocate the necessary space to hold the appropriate memory address. |
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http://bdn.borland.com/article/0,1410,18049,00.html
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| | RAM, Virtual Memory, Pagefile and all that stuff |
| | Physical Address Extension (PAE) is the feature of the Intel 32 bit architecture that expands the physical memory (RAM) address to 36 bits (see KB articles 268363 and 261988). | | | Memory, Committed Bytes - this is a measure of the demand for virtual memory | | | Basic information about the Virtual Memory implementation in 32 bit versions of Windows 2000, XP, 2003 Server etc. |
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http://support.microsoft.com/default.aspx?scid=kb;en-us;555223
(909 words)
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| | Memory address at opensource encyclopedia |
| | It is common to describe the main memory of a computer as a collection of small boxes (cells), which store data and machine instructions. | | | Memory upgrades- A memory and RAM upgrade store by Crucial Technology » | | | In order to access a particular memory location, the processor puts some signals on the address bus, which is typically 32-bits wide in most modern computers. |
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http://www.wiki.tatet.com/Memory_address.html
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| | The page cannot be found |
| | The page you are looking for might have been removed, had its name changed, or is temporarily unavailable. | | | If you reached this page by clicking a link, contact the Web site administrator to alert them that the link is incorrectly formatted. | | | Make sure that the Web site address displayed in the address bar of your browser is spelled and formatted correctly. |
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http://www.absoluteastronomy.com/encyclopedia/m/me/memory_address.htm
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http://eelink.net/~p-nowak/EEC-Archive/doc00167.doc
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