Cycle time, computer memory

Practical applications of photochromism at first (ca. 1955-70) concentrated on the spiropyrans, and especially on BIPS compounds, because of their ready availability, photosensitivity, convenient thermal fade rates, and good color contrast when perceived by the human eye. However, applications in which the dye was required to cycle very many times (e g., an optical binary switch for a photochemical computer memory) or be irradiated continuously (e g., sunglasses, vehicle windshields) were impractical because of the rapid fatigue of these dyes.196... 

Using the techniques discussed in section III and IV we have been able to study the effect of acceleration on ignition of a homogeneous fuel oxydizer mixture. The ability to study multidimensional effects (buoyancy, turbulence etc.) hinges on the use of numerical methods (slow-flow, asymptotic chemistry etc.) which circumvent the time constraints encountered in brute force techniques. These methods go hand in hand with modem fast computers, especially vector machines where judicious programming allows us to attain the actual memory or CPU cycle time. 

In hardware sizing and capacity planning, two sources of data are used. The first is the server capacity, often given as a SPEC mark, or the time in which a standard set of procedures is executed. A less-accurate measure of computing capacity is processor speed in cycles per second. Memory size may play a role in some calculations. BLAST queries, for example, are limited by the fetches from the disk the rule is, the more memory the better. Optimally, the entire nonredundant GenBank database can be stored in memory rather than on disk. The second component of the capacity analysis is the computation load, modeled as a typical workload factors. 

The cycle time of a computer is the time required by the CPU to read the content of one word from memory and restore its content. According to the value of the cycle time, we can distinguish the following types of RAM ... 

Define the following terms as used in relation to computers (a) bit (b) word (c) address (d) memory cycle time (e) interface (f) assembly language (g) machine language... 

After a time Tr measured from the beginning of the selective excitation pulse, the process is repeated for a total of M cycles, each of which uses a different value for the phase-encoding gradient. After this process is complete, a. My. N array of digitally sampled data is available in the computer memory. This data can be converted by a two-dimensional Fourier transform technique into M y N pixel brightness numbers. These numbers can be displayed as an image, which can be viewed either on a cathode ray tube or as a hardcopy on film. 

On a vector computer having vector registers that hold 64 floating-point numbers, this loop would be processed 64 elements at a time. The first 64 elements of Y would be fetched from memory and stored in a vector register. Each iteration of the loop is independent of the previous iteration, so this loop can be fliUy pipelined, with successive iterations started every clock cycle. Once the pipeline is filled, the result, X, will be produced one element per clock cycle and will be stored in another vector register. The results in the vector register will then be stored back into main memory or used as input to a subsequent vector operation. 

Multifunctional Parallelism. The internal architecture of the Advanced Flexible Processor allows multiple computational streams to be constructed and executed in parallel. By way of example, one might imagine the multiply unit requesting operands from one of the memory I/O ports and one of the data memories, while at the same time an adder may be requesting the product computed by the multiplier on a previous machine cycle and another data element from one of the remaining three data memories to serve as input operands for an addition operation. 

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