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Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
memory protection a method for controlling access to memory; e.g., a process may have no access, or read-only access, or read/write access to a given part of memory. The control is typically provided by a combination of hardware and software. memory reference a read of one item of data (usually a word) from memory or a write of one item of data to memory (same as memory reference). memory reference instruction an instruction that communicates with virtual memory, writing to it (store) or reading from it (load). memory refresh the process of recharging the capacitive storage cells used in dynamic RAMs. DRAMs must have every row accessed within a certain time window or the contents will be lost. This is done as a process more or less transparent to the normal functionality of the memory, and affects the timing of the DRAM. memory select line a control line used to determine whether a unit of memory will participate in a given memory access. memory stride the difference between two successive addresses presented to memory. An interleaved memory with a simple assignment of addresses performs best when reference strides are 1, as the addresses then fall in distinct banks. memory swapping the transfer of memory blocks from one level of the memory hierarchy to the next lower level and their replacement with blocks from the latter level. Usually used to refer to pages being moved between main memory and disk. memory width the number of bits stored in a word of memory. The same as the width.
Software Partitioning
Published in Leanna Rierson, Developing Safety-Critical Software, 2017
John Rushby writes: “Spatial partitioning must ensure that software in one partition cannot change the software or private data of another partition (either in memory or in transit) nor command the private devices or actuators of other partitions” [4]. Basically, spatial partitioning prevents a function in one partition from corrupting or overwriting the data space of a function in another partition [9]. Justin Littlefield-Lawwill and Larry Kinnan explain that spatial partitioning assures that shared system resources in one partition “are not consumed in a manner that would result in a denial of service for other partitions requiring access to the same resource” [10]. There are two common approaches to memory protection: (1) using a memory management unit (MMU) or (2) using software fault isolation (SFI).
Comparative Analysis of Delay-Based and Memory-Based Physical Unclonable Functions
Published in IETE Technical Review, 2022
Priti S. Lokhande, Sangeeta Nakhate
Nowadays, embedded systems are used in almost every part of our lives such as cars, mobile phones, pacemakers, traffic light controllers, digital cameras, digital watches and MP3 Players. The majority of contemporary embedded systems, including PDAs, sensors, routers and smart cards, manage and convey sensitive data, making their security a top priority. Embedded systems are also used in safety-critical systems including medical care devices and automotive systems making it very pivotal to secure such systems [1]. As a result, it can be challenging to find an application that does not use one or more embedded systems. Since they are known to employ similar OS and CPU platforms, any algorithm that can attack one of these devices might potentially compromise hundreds of other devices in the same class at once. The majority of developers believe that because their products differ from desktop PCs in that they employ non-x86-based processors and flash storage, they are immune to attacks. In contrast, the authors in [2] argue that the majority of embedded systems lack the five fundamental operating system security characteristics, such as application-kernel separation, memory protection domains, restricted code execution on the system stack, file system access protection and randomization of process information.