Mainframes

Molecular modelling used to be restricted to a small number of scientists who had access to the necessary computer hardware and software. Its practitioners wrote their own programs, managed their own computer systems and mended them when they broke down. Today s computer workstations are much more powerful than the mainframe computers of even a few years ago and can be purchased relatively cheaply. It is no longer necessary for the modeller to write computer programs as software can be obtained from commercial software companies and academic laboratories. Molecular modelling can now be performed in any laboratory or classroom. 

This program has been originally developed and tested on a mainframe computer using the Unix operating system. 

A PC-based H-nmr database, which includes fiiU spectmm search capabiHty, is being constmcted by the Toyohashi University of Technology (67). Speclnfo, owned by Chemical Concepts, offers a 150,000 spectra Hbrary and database system for mainframe computers, which includes H, F, "O,... 

The type of hardware or computer system to be used and the potential size of the database should also be considered. Eor some databases, a personal computer may be adequate. Eor others, especiaUy if there wiU be multiple users, a mainframe computer or a network of personal computers may be required. Storage capacity and response time are parameters that should be considered. However, computer technology changes so rapidly that vendors and computer experts should be consulted when building any personal databases. 

Three types of computer control systems are commonly used for pilot-plant instmmentation. The first is a centralized system, usually based on a minicomputer or occasionally a mainframe. These systems have large storage capacities, substantial memories, and much associated equipment. They typically control all the pilot plants in an area or faciUty. Centralized systems are economical if a large number of units are involved but are becoming less common due to their high installation and maintenance costs as well as the limitation that any failure of the central system shuts down all pilot plants involved. 

The ubiquitousness of the personal computer and the increasing power of the program packages available for it have shifted the emphasis away from large, mainframe-based systems like PLATO. Instead, graphics are included in utihty programs such as equation solvers, spreadsheet processors, and word processors. 

Computer platforms where 1 represents IBM PCs and compatibles, 386 or better 2, Unix-based work stations (or equivalent) including HP/ApoUo, SUN, and IBM RS6000 3, DEC VMS 4, IBM mainframe, MVS or VM, or compatible and 5, others including Cray, Data Gen., etc. 

Spreadsheet Applications. The types of appHcations handled with spreadsheets are a microcosm of the types of problems and situations handled with fuU-blown appHcation programs that are mn on microcomputers, minis, and mainframes and include engineering computations, process simulation, equipment design and rating, process optimization, reactor kinetics—design, cost estimation, feedback control, data analysis, and unsteady-state simulation (eg, batch distillation optimization). 

MIMD Multicomputers. Probably the most widely available parallel computers are the shared-memory multiprocessor MIMD machines. Examples include the multiprocessor vector supercomputers, IBM mainframes, VAX minicomputers. Convex and AUiant rninisupercomputers, and SiUcon... 

The equations of state will not be further described or presented in more detail as tliey are unfortunately somewhat difficult to solve without the use of a computer. Full details are available in the referenced material for those wishing to pursue this subject further. In the past, these equations required the use of a mainframe computer not only to solve the equations themselves, but to store the great number of constants required. This has been true particularly if the gas mixture contains numerous components. With the power and storage capacity of personal computers increasing, the equations have the potential of becoming more readily available for general use... 

Most monitors are display terminals that use cathode-ray tube (CRT) displays, which function by exciting a layer of phosphors with an electron gun. These devices include monitors used with PCs and terminals used with mainframes or minicomputers. Features such as color, resolution, and size influence power requirements. Most PC monitors are... 

The development of any program must take into consideration the maintenance tasks that need be carried out and the resources available, thereby ensuring that product quality and personnel safety standards are met. It follows that operational demands, whether they be from a service utility installation, a production line, a mainframe computer or an office environment, will play a major part in reaching the decision as to what type of maintenance program requires implementation. 

Rt is ironic that such an intensely computational mathematical science as chaos theory owes much of its modern origin to calculations that were performed not on a large mainframe computer but rather a simple programmable pocket calculator, a Hewlett-Packard HP-65 Feigenbaum would explain years later that had the series of intermediate calculations not been carried out sufficiently slowly, it is likely that most of the key observations would have been missed [feigSOa]. 

Primary structure Mainframe of a product is the primary structure, Examples include aircraft main supports, building main beams, and automobile frames. If the primary structure fails, it would be damaging or catastrophic to the product and/or people. See Secondary structure. 

If the system is modest and stand-alone (perhaps based on a small minicomputer or super microcomputer), only the acquisition cost may be significant. If the system needed is a large and expensive one (such as would be based on a mainframe or super minicomputer) and if it requires specially prepared and/or air conditioned facilities, much cable installation and/or on-going service contracts, then all cost factors may require consideration. 

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