Disk storage capacities

With 2D spectra, depending on the kind of experiment, problems with resolution and/or sensitivity may arise. Resolution is an inherent problem with 2D experiments and is mainly caused by the limited amount of spectrometer time and disk storage capacity. Sensitivity may be a problem when measuring small sample amounts or weak effects (NOESY, ROESY,. ..). In heteronuclear 2D experiment.s the sensitivity problem is more pronounced with X- rather than with H detection. 

Concomitant with the increased data size, the memory requirements for permanent storage will render It necessary to expand the storage capacity of backup stores. Disk storage capacities of over 100 M-byte, as they have become available in the form for example of the CDC 9730 Series, are a true necessity in many hlgh-fleld NMR applications. Memory requirements are particularly severe in two-dimensional spectroscopy such as the 2D-J experiments where spectral arrays are obtained In which spin-spin coupling Is separated from chemical shielding. A 10 ppm x 50 Hz 2D spectrum with a digital resolution of 2 Hz on the axis and 0.2 Hz on the J axis, for example, corresponds to a 4 M-word data matrix. 

With the current impressive CPU and main memory capacity of relatively in expen sive desktop PC s, non-direct SCFaft tnilto calculations involving 300-400 basis function scan be practical. However, to run til esc kin ds of calcti latiori, 20 GBytes of li ard disk space rn ight be needed. Such big disk space is unlikely to be available on desktop PCs.. A direct SCb calculation can elim inate th e n eed for large disk storage. 

MO Media Summary. When compared to magnetic recording on hard disks, the advantage of MO data storage is the removabiUty of the disks and the high storage capacity (especially on multiplatter (juke-box) systems) whereas the access times have not yet been reached. 

The purpose of interfacing instruments with computers is to enable raw analytical data to be collected as it is produced, then processed, stored and displayed or printed out. This may be accomplished as it is gathered, i.e. in real-time, or at some later time, i.e. post-run. Complete chromatograms or spectra can easily be stored in the main memory or RAM or transferred to disk. The immense storage capacity of mainframe computers can be used to provide large libraries of data (data banks) for future reference. 

If some care is not taken, a calculation may be needlessly limited by the storage capacity of central memory, disks, or tapes. 

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