|
| |
| | Memory protection - Wikipedia, the free encyclopedia |
 | | Memory protection is a system that prevents one process from corrupting the memory of another process running on the same computer at the same time. | | | Parts of an application's memory can be "swapped out" to other forms of storage. | | | On a memory access the hardware checks that the current process's protection key matches the value associated with the memory block being accessed; if not, an exception occurs. |
|
http://en.wikipedia.org/wiki/Protected_memory
(662 words)
|
|
| |
| | Extended memory - Wikipedia, the free encyclopedia |
| | The memory is "protected" in the sense that memory segments assigned a local descriptor cannot be accessed by another program because that program uses a different LDT, and memory segments assigned a global descriptor can have their access rights restricted, causing a hardware trap (typically a General Protection Fault) on violation. | | | Extended memory is only available on PCs based on the Intel 80286 or higher processor, as only these chips can access more than 1MB of RAM. | | | In this case, the extended memory is provided by a supervising protected-mode operating system such as Microsoft Windows. |
|
http://en.wikipedia.org/wiki/Extended_memory
(318 words)
|
|
| |
| | Introduction to Protected-Mode |
| | 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. | | | The 8086 gained an enormous popularity soon after its introduction, since it was chosen by IBM engineers when they designed the first personal computer (they actually used a variant of the 8086 known as the 8088 but the differences are minor). |
|
http://www.internals.com/articles/protmode/introduction.htm
(1391 words)
|
|
| |
| | smartcards |
| | With the exception of Atmel's new AT88SC1616C, protected memories all use proprietary protocols developed on a chip by chip basis before the PCSC standard for smartcard reader drivers was developed. | | | Because the protocol changes from one protected memory to another, finding development tools generally means first deciding on a reader and then asking its manufacturer for the development tools you will need. | | | This device is optimized as a "secure memory" for smartcard applications without the requirement of an internal microprocessor. |
|
http://www.vct.com/VCT/website/smartcards_pm.html
(832 words)
|
|
| |
| | Protected-Mode Memory Management |
| | After loading a page from disk and remapping it to physical memory, the operating system reexecutes the instruction which caused the page fault exception to occur, so the running application is not even aware of the fact that part of its memory was stored temporarily on disk. | | | Descriptor tables reside in system memory and are used by the processor to perform address translation. | | | Decreasing the segment limit value in an expand-down segment causes memory to be allocated at the bottom of the segment. |
|
http://www.internals.com/articles/protmode/protmode.htm
(2289 words)
|
|
| |
| | [No title] |
| | Now, whenever the user overwrites his memory, even by one byte, he writes to the protected memory, and the operating systems generates what's called a "Segmentation Fault", and kills his process. | | | True, at one point the memory at this address WAS accessed, but we told the operating system to discard that, and replace it with protected memory instead. | | | The default C library memory allocator malloc devides up system memory and returns the requested length of memory to the user. |
|
http://webs.sinectis.com.ar/lesanti/backup-20050807/algo2/njamd.txt
(650 words)
|
|
| |
| | Protected Mode Basics |
| | As a solution to this compatibility problem, IBM decided to AND the A20 output of the CPU with a programmable output pin on some chip in the computer. | | | In protected mode, memory segmentation is defined by a set of tables (called descriptor tables) and the segment registers contain pointers into these tables. | | | Protected mode differs from real mode in this respect each time the CPU loads a segment register, it fully loads the descriptor cache register, no previous values are honored. |
|
http://www.x86.org/articles/pmbasics/tspec_a1_doc.htm
(4153 words)
|
|
| |
| | Sizing memory in Protected Mode |
| | To determine how many banks of memory are in the computer, we test the existence of RAM for each bank. | | | In our computer, chip size in each RAM bank is programmable; therefore we need to determine the size of the chip in the socket and subsequently re-program the memory controller before we can have full access to all the memory in the computer. | | | Since we can't re-program the memory controller (or make any assumptions about the existence, state, or programmability of a cache controller), we must write an algorithm that can detect the presence of memory without the intrusion of cache RAM. |
|
http://www.x86.org/articles/memsize/memsizing.htm
(1520 words)
|
|
| |
| | Hexapedia - IA-32 |
| | Another one is virtual memory, which lets programs use more memory than is physically installed on the machine. | | | One of them is protected memory, which prevents programs from corrupting one another. | | | The IA-32 instruction set is usually described as CISC (Complex Instruction Set Computer) architecture, though such classifications have become less meaningful with advances in microprocessor design. |
|
http://www.hexafind.com/encyclopedia/IA-32
(2572 words)
|
|
| |
| | Method and system for providing access to a protected partition of a memory device utilizing a passthru command - ... |
| | A DASD is typically a memory device such as a hard disk-drive device, a floppy disk-drive device or a large RAM memory which emulates a disk drive. | | | The fence is a particular address designating a portion of memory over (or under, depending on the memory scheme) which a reference to DASD memory is rejected as an illegal reference to a protected memory partition. | | | The present invention is a method for accessing data in a fenced area on a SCSI compatible memory device while the computer's operating system is running and without moving the fence or affecting the storage device subsystem integrity. |
|
http://www.freepatentsonline.com/5754821.html
(5346 words)
|
|
| |
| | Code protection in microcontroller with EEPROM fuses - Patent 5469557 |
| | The device includes a CPU, program memory for storing instructions to be executed by the CPU to perform its control functions, and data memory for storing data for selective retrieval by the CPU. | | | In addition, after the protected contents are erased (rendering them invulnerable to retrieval), a further safeguard is implemented by causing the memory to be rewritten with arbitrary data from the mose recent "load" command. | | | It is desirable to implement the logic to erase the contents of both the program memory and the data memory even if only one of the two is code protected by an EEPROM fuse, to further discourage the possibility of retrieval of any useful information from the device by tampering. |
|
http://www.freepatentsonline.com/5469557.html
(2314 words)
|
|
| |
| | Glossary of Terms |
| | RAM (random access memory) is the place in a computer where the operating system, application programs, and data in current use are kept so that they can be quickly reached by the computer's processor. | | | Memory caching is effective because most programs access the same data or instructions over and over. | | | Unlike a computer's random access memory (RAM), the data in ROM is not lost when the computer power is turned off. |
|
http://www.ami.com/support/glossary.cfm
(13219 words)
|
|
| |
| | MacAddict Forums / Protected memory or no, AOL & ViaVoice fight! |
| | Protected memory just means that if one application crashes, it doesn't corrupt the whole memory of the computer, which brings down the whole thing. | | | This protected memory feature of Mac OS X seems to be over-hyped. | | | I have plenty of memory and I can run other programs simultaneously with ViaVoice that take up much more memory than AOL with no problem. |
|
http://www.macaddict.com/forums/topic/17904
(347 words)
|
|
| |
| | Caldera DR-DOS DPMS API Guide |
| | The tables are in memory and have one entry, called a descriptor, per segment. | | | This applies both to memory allocated via the native extended or expanded memory interface and that allocated via DPMS, as the DPMS server normally calls down to the underlying memory manager to allocate the physical memory required. | | | The cache could still use XMS memory with DPMS, but this would mean that calls to the XMS driver to do block moves to and from the memory would involve mode transitions and would therefore be slower than without DPMS. |
|
http://www.drdos.com/dosdoc/dpms/01dpms01.htm
(3285 words)
|
|
| |
| | Protected Memory |
| | The old Macintosh, good for it's day, was eventually chided greatly for it's lack of protected memory by UNIX advocates and later Windows advocates. | | | Why Protected Memory is bad for Software Engineering | | | Sofware that destabilized or outright crashed your computer didn't win any love from the populous. |
|
http://bolson.org/rant/memoryProtection.html
(153 words)
|
|
| |
| | Processes |
| | The memory object must be obtainable immediately, either by sharing or by allocating free physical memory. | | | At the moment of creation of the region, the memory object is either allocated from free physical memory or shared with the memory object of another region. | | | At region creation time, the memory object is either allocated from free physical RAM memory or shared from the memory object of another region. |
|
http://www.jaluna.com/doc/c5/html/Overview/x7648.html
(3795 words)
|
|
| |
| | ProtectedMode overview [deinmeister.de] |
| | This is more theoretical, not only due to CPU speed and memory limits, but mainly because you need the Protected Mode for preventing programs from disturbing other programs or the OS. | | | Even today, more than a decade since the introduction of the 386, computers use only a small percentage of the 4 GB of RAM which can be used together with a 386. | | | Paging on the 286 was easy, every computer had enough RAM to load and store a complete logical memory block into physical RAM. |
|
http://www.deinmeister.de/x86modes.htm
(1255 words)
|
|
| |
| | Apple - Mac OS X - UNIX |
| | The Mach kernel augments standard virtual memory semantics with the abstraction of memory objects. | | | UNIX users will feel at home in Darwin, the robust BSD environment that underlies Mac OS X. That environment is accessible at any time from the Terminal application. | | | Tiger’s state-of-the-art kernel features improved SMP scalability and 64-bit virtual memory, while standards-based access control lists take UNIX permissions to the next level. |
|
http://www.apple.com/macosx/features/unix
(700 words)
|
|
| |
| | Password Protected Memory Card |
| | In addition, 32 of the 256 Bytes can be assigned a protection bit, which enables permanent data locking. | | | The ASECard MP42 card is a popular solution for applications where data can be exposed while updating the data has to must be protected. | | | ASECard MP42 is a memory smart card with intelligent security logic. |
|
http://www.athena-scs.com/product.asp?pid=10
(106 words)
|
|
| |
| | screaming-penguin.com |
| | it the software to protect the data requires windows, or really any other outside anything, then its useless because this could be protected by any other similar input device that can be put in front of ANY data, USB flash or not. | | | hell if i buy any fingerprint io device (which are available) i cant make a floppy drive "protected" in the same manner. | | | I agree, inside the device would be optimal. |
|
http://www.screaming-penguin.com/main.php?storyid=4239
(754 words)
|
|
| |
| | NOVELL: Cool Solutions: Trouble Loading in Protected Memory |
| | There appears to be a hardware incompatibility with the Bio Star motherboard when CLIB.NLM is loaded into protected memory if it must auto-load all of the supporting modules. | | | STARTIFOLDER.NCF attempts to load APACHE.NLM into protected memory. | | | NOVELL: Cool Solutions: Trouble Loading in Protected Memory |
|
http://www.novell.com/coolsolutions/qna/1472.html
(142 words)
|
|
| |
| | Protected Mode Memory Addressing |
| | is used to reduce the number of actual memory references needed to construct the physical address. | | | Indicates how the instructions (80386 and up) access register and memory data in protected mode. | | | (and LDT) are located in the memory system. |
|
http://www.cs.umbc.edu/~plusquel/310/slides/micro_arch2.html
(675 words)
|
|
| |
| | Antipixel Blog Protected memory |
| | Richard —- I replaced the default memory configuration with 2 GB of RAM from Other World Computing (that link does not yet constitute an endorsement: this is the first time I’ve bought anything from them, but they seemed to get good reviews from people on various forums). | | | As for checking memory and swap file status, try the Activity Monitor (in the Utilities folder). | | | Not the kind of memory protection I had in mind. |
|
http://www.antipixel.com/blog/archives/2004/10/03/protected_memory.html
(974 words)
|
|
| |
| | Protected Memory |
| | This serves two purposes: it protects the privacy of information from other processes (perhaps being run by a different user), and it keeps malicious or wayward programs from writing into another process' data. | | | The kernel ensures that a process accesses only memory which it has allocated. | | | When a process attempts to access memory outside of its memory space, it is killed by the kernel via a Segmentation Fault. |
|
http://www.stllinux.org/meeting_notes/1998/0319/node7.html
(68 words)
|
|
| |
| | ITworld.com - Protected memory spaces |
| | The syntax for some of the more-useful protection options is as follows: | | | PROTECT ncf-file-name - this loads all modules in an NCF file into a protected address space. | | | This is a far-better-designed system then NetWare 4's domain option (which also loaded an NLM into a protected memory area) with much richer choices - provided you're aware of them. |
|
http://www.itworld.com/Comp/2298/NWW01030700477526/pfindex.html
(221 words)
|
|
| |
| | Lookout Discussion Forums - Attempted to read or write protected memory |
| | Warning: Accounts: ignoring error Attempted to read or write protected memory. | | | This is often an indication that other memory has been corrupted. | | | Lookout Discussion Forums - Attempted to read or write protected memory |
|
http://www.lookoutsoft.com/forums/topic.asp?TOPIC_ID=573
(66 words)
|
|
| |
| | Developing NLM to run in protected memory |
| | The customer wants it to run in Protected Memory. | | | Next message: Developing NLM to run in protected memory | | | Is there anything regarding development/coding I should know in order to make this happen successfully? |
|
http://forge.novell.com/pipermail/libc-dev/2004-May/000520.html
(72 words)
|
|
| |
| | Juice/VM.java |
| | */ protected boolean reschedulePlease() { threadScheduler.reschedule(); _Thread t = threadScheduler.currentThread; if (t != null) currentFrame = t.topFrame; else { // System.out.println("No more threads left! | | | */ protected Scheduler threadScheduler; /** * TypeChecker object */ TypeChecker typeChecker; /** * Signals from the user space to VM to perform specific operation. | | | */ protected MethodFrame currentFrame; /** * Hashtable containing all strings objects available to the VM */ protected Hashtable stringObjects; /** * All threads (processes) are managed centrally by the scheduler. |
|
http://www.cs.purdue.edu/homes/bahmutov/cs510/VM/ptype/Juice/VM.html
(227 words)
|
|
| |
| | Protected Memory |
| | Mach controls applications so they cannot write into one-anotherís or the systemís memory space |
|
http://www.hmug.org/Pres/MacOS_X_PB/tsld010.htm
(28 words)
|
|
| |
| | [f2py] Protected memory in shared fortran libs? |
| | All: Supposed I have a shared fortran lib which allocates an array, call it U() I have a python application which loads a shared lib that has the "U" - it allocates it, inits it, maybe writes it to a file. | | | Now, from that python application I want to spawn another job (e.g., via the 'os.system()' command) which starts another python job that loads the SAME shared library, creates memory, reads data into U(), does calculations on it, etc. So the shared lib is loaded into two programs at once. | | | I assume that the multiple "invocations" of loading that module creates two separate regions of memory, correct? |
|
http://cens.ioc.ee/pipermail/f2py-users/2005-March/001077.html
(236 words)
|
|
| |
| | Omni Web Forum: GEE Whiz Abend (in protected memory) |
| | Occasionally GEE Whiz (started with geep.ncf) abends in protected memory and the following dump is given: | | | Removed address space because of memory protection violation | | | Omni Web Forum: GEE Whiz Abend (in protected memory) |
|
http://www.omni-ts.com/Forum/post--778--page-1.html
(423 words)
|
|
| |
| | [f2py] Re: Protected memory for fortran.. |
| | Previous message: [f2py] Protected memory in shared fortran libs? | | | Okay, I figured this out - and invocations are separated. |
|
http://cens.ioc.ee/pipermail/f2py-users/2005-March/001078.html
(58 words)
|
|
|
