Direct-access-file

RECL returns record length in direct access file... 

NEXT REC returns number of next record in direct access file BLANK returns whether blanks or zeros specified... 

Update and retrieval in direct access files using hash algorithm... 

Before any large number or alphanumeric key is used for addressing a record in the direct access file, it must be transformed into a number between 1 and N, N being the length of this file. The procedure employed for such transformation is called hash algorithm (ref. 5). 

One of the most commonly used hash algorithm employs twin prime numbers (two consecutive odd numbers that are both primes) and modulo function. If KEY is a large number (fragment ID or XOR-ed parts of chopped long string) and NP the length of the direct access file than the calculated address ADDR and the increment INCR can be obtained by the following equations ... 

The file BND/YY/B, which after execution of LMTO (if NOEVC = 1) contains the eigenvalues and ti characters, is a random (direct) access file. This file organisation very often causes problems when LMTOPACK is implemented on machines other than Burroughs B7800. The problem is that the Burroughs, for which the programmes were written, allows sequential write and subsequent random read in a file with fixed record length, while most other machines do not. 

This scheme overcomes many of the disadvantages of the other schemes it does not require an estimation of file size, files can grow organically, the file map can be copied into memory for speed of access, it facilitates direct access, file size (up to the entire capacity of a disk) is not limited artificially, and defragmentation is not required. Its one disadvantage is that of less than optimal performance in sequential processing of a file. Where such performance is desirable, it could only be achieved by putting a file on... 

All input spectra and structures must also be saved in direct access files for later use in the iterative process or for checking the results. Different data types (structures, spectra, sets of commands) must be coded uniformly in all system modules for input and output. The same is true for the files on which the final or intermediate results are stored. Because a resulting output file of one module may act as an input file to another one, or be used as an input for starting a new problem, all data exchange processes and files must be standardized. Good library search systems perform the reformatting of data transparently to the... 

A hash code is a fixed length repre.sentation of a data structure used as an index or key to a direct access file. The input structure cannot be restored from a hash code, and due to the limited range of values two different data structures may be represented by the same hash code. The basic steps of generating the 64-bit hash code ACMF were presented in Section 8, together with some examples of molecules with identical ACMF code. 

For direct access to files for edit, rename, delete... 

The PCs of the system administrator and a few special users have direct access to the DRX-spectrometer.s via the central Server using the FTP protocol. This special group have direct access to any files in the spectrometer s data system, i.e. data files, variou.s lists, pulse programs,... and may transfer files to and from the spectrometers. In addition, they also have the option to create or delete directories, to modify pulse programs and to do other jobs on the spectrometer s data system. As is usual in security sensitive situations, this special group require a password to acces.s the spectrometer. 

The utilization of patent information is, of course, promoted by diverse patent authorities. The European Patent Office (http //www.european-patent-office.org/) provides a service called esp cenet, which is easily accessible via the Internet (http //ep.espacenet.com/). In addition, inventors might conduct online file inspections via a service called epoline, which can be reached at http //www.epoline.org/. The user gains direct access to all published European patent applications and patents stored in electronic form. Patent information services are also offered by the United States Patent and Trademark Office (http //www.uspto.gov/). 

MARPATy produced by Chemical Abstracts Service, contains the generic structure records for patent publications since 1988, which are included in the CA file. Sources include patents from 26 countries plus EPO and PCT publications. Bibliographic records for retrieved references can be directly accessed in this database (101). 

FILE 1 iUNFORMATTED,TYPE=RANDOM (DIRECT) ACCESS, ... 

In some applications, such as self-marked multiple choice tests for large classes, it is important that the students should not have direct access to files containing the questions, the answers or the scores. All that is required is a simple system of marking their work and here devices such as optical mark-sense card or document readers can ensure simple, secure and fast input. These devices can detect marks made in pencil or pen on specially-printed cards or sheets. Each card or sheet read can contain the responses to dozens of questions and can be read in less than 1 s. Very large classes can be handled using a single microcomputer [3, 4]. 

The ALCHEM transforms are gathered together in unordered sequential source files. These source files are compiled by SYNCOM into efficient binary direct access CHM files complete... 

For direct access to any record in response to a random enquiry, calculation of where to find the record within the file is also very simple and very quick. 

Locating an individual record directly involves following what could be a long chain of pointers fl om the beginning of a file to the desired record true direct access is not feasible. 

The method is best suited for applications which do not require high-performance direct access to records stored on disk, but is highly suitable where files regularly grow in size and where the operator or user does not wish to be bothered with technical details such as defragmentation. 

When the installation is complete click the OK button on the Opening screen (Fig. 3.1) displaying the dialog box (Fig. 3.2). Check out the Data File Name (direct access) option and click OK. 

---