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Computer memory systems
Published in Joseph D. Dumas, Computer Architecture, 2016
Optical memories are becoming more and more common—all the way down to low-end computer systems. Even inexpensive personal computers often have an optical drive that can at least read and often write various types of optical disks including compact disks (CDs), digital versatile disks (DVDs), and/or Blu-ray disks (BDs). Depending on type, an optical disk can store anywhere from several hundred megabytes of data (CD) to as much as 50 GB (Blu-ray) at a typical price of less than one dollar each. In addition to their low cost, optical disks offer most of the same advantages (portability, nonvolatility, and high density) as magnetic disks and also are immune to erasure by magnetic fields. They are much too slow to be used for main memory, however, and the writing process takes considerably longer than writing to a magnetic disk. Their most common uses are for distribution of software and digitally recorded audio/video and as an inexpensive form of backup/archival data storage.
Distributed Control Systems (DCS)
Published in Douglas O. J. deSá, Instrumentation Fundamentals for Process Control, 2019
The Manufacturing Automation Protocol (MAP) standard communications protocol used today by almost all DCS manufacturers was forced on instrument makers by financial pressure exerted by GM. Within MAP is the ISO Seven-Layer Model for communications. Layers 1 through 4 taking care of the physical properties and transmission, and layers 5 through 7 the applications. Operators and engineers interface with the system at the upper layers. The data transmission speeds are: the carrierband LAN (local area network) 5 Mbit/s, and the broadband LAN 10 Mbit/s—i.e., up to about 1 million characters per second or about one megabyte per second.
Technology Beyond the Standard
Published in Klaus Diepold, Sebastian Moeritz, Understanding MPEG-4, 2012
Klaus Diepold, Sebastian Moeritz
In a communications environment, engineers measure the number of bits that need to be transmitted from A to B. Therefore, bit rates for transmission are measured in terms of bits per second. As indicated above, there is a factor of 8 between ‘bits per second’ and ‘Bytes per second’, which seems simple enough. Unfortunately, the situation is slightly more complicated. A kilobyte (KB) denotes 210 = 1024 Bytes = 1024*8 bits, whereas a kilobit (kbit) = 1000 bits. Similarly, 1 Megabyte (MB) denotes 1024*1024 = 220 Bytes, and a Megabit (Mbit) is 1000*1000 = 106 bits.
Job failure prediction in Hadoop based on log file analysis
Published in International Journal of Computers and Applications, 2022
Ehsan Shirzad, Hamid Saadatfar
Another parameter that can affect the jobs status is the volume of input/output data. To study this parameter, we considered the read and write byte counters of the jobs and calculated the sum of the values of these counters. Figure 3 shows the status of the jobs in I/O data volume ranges. In byte range (from one byte to less than one kilobyte) and KB range (from one kilobyte to less than one megabyte), the success rate of the jobs is almost the same and near 100%. However, an increase in I/O data volume decreases the success rate of the jobs, generally; and in TB range (one terabyte of I/O volume and more), the failure rate of the jobs is greatly increased. Thus, I/O data volume is another useful feature that we derived from the log files.