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Organic–Inorganic Semiconductor Heterojunctions for Resistive Switching Memories
Published in Ye Zhou, Optoelectronic Organic–Inorganic Semiconductor Heterojunctions, 2021
The main characteristic of WORM memory devices is that they can be written only once but the written information can be permanently stored, as shown in Figure 11.1c. Accordingly, WORM memory devices are mainly applicable to store the information with high reliability but small capacity, such as the basic input/output system programs for computers and the electronic instructions for production and testing equipment. Compared with the commonly used erasable programable read-only memory that relies on three-terminal crystalline Si transistors, the newly proposed WORM resistive switching memory has huge advantages in terms of simple structure, easy fabrication, and high-density integration.
W
Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
write allocate (or end-effector). Usually, wrist allows an orienting of the manipulator. Therefore, the main role of the wrist is to change the orientation of the hand (or end-effector). See also spherical wrist. write allocate part of a write policy that stipulates that if a copy of data being updated is not found in one level of the memory hierarchy, space for a copy of the updated data will be allocated in that level. Most frequently used in conjunction with a write-back policy. write broadcast a protocol for maintaining cache coherence in multiprocessor systems. Each time a shared block in one cache is updated, the modification is broadcast to all other caches. Also referred to as write update. write buffer a buffer that stores memory write requests from a CPU. The write request in the buffer are then served by the memory system as soon as possible. Reduces the number of processor wait cycles due to long latency write operations. write instruction a processor instruction that stores information into memory from a processor register or a higher level cache. write invalidate a protocol for maintaining cache coherence in multiprocessor systems. Each time a shared block in one cache is updated, a message is sent that invalidates (removes) copies of the same block in other cache memories. This is a more common alternative than write broadcast protocols. write once read many (WORM) used to refer for memory devices that allow data to be written once after device fabrication, and to be read any number of times. A typical example is PROM. write policy determines when copies of data are updated in a memory hierarchy. The two most common write policies are write through and write back (copy back). write through a write policy that stipulates that when a copy of data is updated at one level of a memory hierarchy, the same data are also updated in the next outer level. Write through is usually only used in low-level caches. Its advantages are that it is fast and simple to implement, and that it always guarantees that the next level of the memory hierarchy has a valid copy of all data. Its main disadvantage is that it generates much data traffic to the next level. write update See write broadcast. See antidependency. See output depen-
A package-less SAW RFID sensor concept for structural health monitoring
Published in Mechanics of Advanced Materials and Structures, 2021
Hugo Chambon, Pascal Nicolay, Cécile Floer, Ayech Benjeddou
Surface acoustic wave (SAW) devices are part of the radio frequency identification (RFID) passive sensors that can be used for structural health monitoring (SHM) applications [1]. Compared to the integrated-circuit (IC)-based RFID sensors, SAW devices benefit from a higher dynamic range which is limited by the reader used to interrogate the sensor remotely [2]. In theory, they can be interrogated from a longer distance [3]. SAW sensors are also simpler (in the sense that they have no embedded electronics) because they do not need to harvest their energy from the enquiring signal, meaning that they are more prone to harsh environment, in particular high temperature, applications [4]. They are also non-programable (Write Once Read Many) WORM devices. However, this feature can be seen as an advantage for security but also as a drawback for these devices versatility.