Direct Access Storage Device
In mainframe computers and some minicomputers, a direct access storage device, or DASD ( /ˈdæzdiː/), is any secondary storage device which has relatively low access time relative to its capacity.
Historically, IBM introduced the term to cover three different device types:
- disk drives
- magnetic drums
- data cells
The direct access capability, occasionally and incorrectly called random access (although that term survives when referring to memory or RAM), of those devices stood in contrast to sequential access used in tape drives. The latter required a proportionally long time to access a distant point in a medium. Note: The storage CLASS of DASD is both Fixed and Removable. The access methods for DASD are Sequential, Indexed and Direct.
Read more about Direct Access Storage Device: Architecture, Access, Present Terminology
Famous quotes containing the words direct, access, storage and/or device:
“O wretched fool,
That lov’st to make thine honesty a vice!
O monstrous world! Take note, take note, O world,
To be direct and honest is not safe.”
—William Shakespeare (1564–1616)
“In the greatest confusion there is still an open channel to the soul. It may be difficult to find because by midlife it is overgrown, and some of the wildest thickets that surround it grow out of what we describe as our education. But the channel is always there, and it is our business to keep it open, to have access to the deepest part of ourselves.”
—Saul Bellow (b. 1915)
“Many of our houses, both public and private, with their almost innumerable apartments, their huge halls and their cellars for the storage of wines and other munitions of peace, appear to me extravagantly large for their inhabitants. They are so vast and magnificent that the latter seem to be only vermin which infest them.”
—Henry David Thoreau (1817–1862)
“A bracelet of bright hair about the bone,
Will he not let us alone,
And think that there a loving couple lies
Who thought that this device might be some way
To make their souls, at the last busy day,
Meet at this grave, and make a little stay?”
—John Donne (1572–1631)