Core memory, computer

Hash codes of molecules which are already pre-computed are suitable for use in fiill structure searches in database applications. The compression of the code of a chemical structure into only one number also makes it possible to compute in advance the transformation results for a whole catalog. The files can be stored and kept complete in the core memory during execution of the program, so that a search can be accomplished within seconds. 

Today, dynamic random-access memories (DRAMs) are transistor/capacitor-based semiconductor devices, with access times measured in nanoseconds and very low costs. Core memories were made of magnetic rings not less than a millimetre in diameter, so that a megabyte of memory would have occupied square metres, while a corresponding DRAM would occupy a few square millimetres. Another version of a DRAM is the read-only memory (ROM), essential for the operation of any computer, and unalterable from the day it is manufactured. We see that developments in magnetic memories involved dramatic reductions in cost and... 

In this chapter, we also discussed several schemes that allow for the computation of scalar observables without explicit construction and storage of the eigenvectors. This is important not only numerically for minimizing the core memory requirement but also conceptually because such a strategy is reminiscent of the experimental measurement, which almost never measures the wave function explicitly. Both the Lanczos and the Chebyshev recursion-based methods for this purpose have been developed and applied to both bound-state and scattering problems by various groups. 

Data Reduction. The spectral data can be collected on-line and stored directly on magnetic tape under control of a PDP-8 digital computer 11). Alternatively, they can be collected on a magnetic core memory, then transferred in bulk fashion (Figure 14). The choice of method is dictated by the length of counting required and by the method of treatment of the data (i.e., simple X-Y plot or complete channel information). 

The automation concept implemented at Conroe is called computer production control (CPC).2 CPC systems are driven by a general purpose process-control computer (48-K core memory) centrally located and programmed to monitor production and equipment operations and perform oil and gas accounting. As shown in Fig. 11, the computer is connected to a supervisory control system with a computer interface unit (CIU) to provide remote data acquisition and control function capability. 

The original WOA supervisory control and data acquisition system was configured around the Honeywell HS4400 process computer. Two 4400s in dual redundant processor configuration were installed with automatic failover to the standby should the online unit fail. Each 4400 has 96K of 24-bit word magnetic core memory and a 1.3 million word drum. 

An estimate of the number of tests also is necessary for estimating computer core memory requirements if the data reduction workload is so heavy that computer data storage seems attractive. 

An NMR spectrometer capable of PFT measurements is a combination of a CW circuit such as found in conventional NMR spectrometers [1-5], a computer controllable pulse generator, and a small digital computer of core memory size 8-256 K. Fig. 2.34 outlines this experimental arrangement. 

The PFT NMR spectrum can then be recorded in analog or digital form by a plotter controlled by the computer. If the computer core memory allows, additional subroutines may be stored which automatically compute signal intensities and positions (in ppm values relative to some standard or in Hz) and outputs them to the printer. 

In recent years the area of solid-state chemistry has become increasingly important to chemists. The development of memory cores for computers, phosphors, transistors, lasers, etc., has resulted in the synthesis of many new materials. Methods have had to be developed for both the preparation and characterization of these compounds. 

Scattered light collected by the FI.5 lens (f = 30 cm) is relayed to the photomultiplier tube via 1 mm slits, a 1 nm bandwidth interference filter and a polarization filter, to reduce background from flame luminescence. The PDP-11/34 computer instructs the A/D convertor to make a conversion every 100 vsec. The resulting digital data are stored sequentially in core memory. The memory is saturated at 16,000 temperature measurements, at which time the data are transferred to a hard disk memory. The data in this transfer constitute one time... 

Ferrites having a square hysteresis loop (e.g. (Mg, Mn, Zn) Fe204), developed for the now outdated computer core memories, have found applications in the form of a toroidal saturable inductor for regulating the output currents in switched-mode power supplies. 

In this scctioin we describe typical computer requirements for the 0( D) + Ho reaction. The TB, TJ and TK codes use about 2 GBytes of core memory. They have been implemented on a NEC-SXo vector computer (8 Gflops peak performance per processor) at IDRJS/CNRS (Orsay, France). All the codes are efficiently vectorized and use the optimized BLAS and LAPACK linear algebra libraries. 

Rectangular ferrites are utilized in core memory systems in computers... 

When the basis set representing the interacting system s potential is of a dimension that allows storage of the Hamiltonian matrix in the computer core memory, the total scattering problem can be solved easily and simultaneously at all energies by a single diagonalization of the real symmetric Hamiltonian matrix. 

The solution of the scattering problem, if N is not so large as to make even the operating with the matrices A+ difficult, reduces now to evaluation of the effect of (E — H) l (or, equivalently, (E — H + uexl) ) on the set x . When the Hamiltonian matrix can be stored in the computer core memory it is possible to simply diagonalize it and to construct out of the eigenvalues E, and eigenfunctions tp, a solution at any desired energy from the spectral form of Eq. (9) ... 

When the basis size is small enough to store the Hamiltonian matrix in the computer core memory, two things can be said with confidence. First, the method presented in Sec. II based on Eq. (1) and Eqs. (2) and (9) (or better to avoid anomalies, (1) and (21)) are very easy to comprehend and implement. This is especially true when the diagonalization of the full Hamiltonian is the key computational step. Second, there are many other approaches, such as the Kohn variational principle (21), the / -matrix theory (35), and the closely related, log-derivative methods (22, 23), that are easy to implement and anomaly free. The methods which use absorbing potentials clearly have a disadvantage relative to the above methods in the sense that they require larger than minimal basis sets and involve non-Hermitian matrices. 

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