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:
“As for your friend, my prospective reader, I hope he ignores Fort Sumter, and “Old Abe,” and all that; for that is just the most fatal, and, indeed, the only fatal weapon you can direct against evil ever; for, as long as you know of it, you are particeps criminis. What business have you, if you are an “angel of light,” to be pondering over the deeds of darkness, reading the New York Herald, and the like.”
—Henry David Thoreau (1817–1862)
“A girl must allow others to share the responsibility for care, thus enabling others to care for her. She must learn how to care in ways appropriate to her age, her desires, and her needs; she then acts with authenticity. She must be allowed the freedom not to care; she then has access to a wide range of feelings and is able to care more fully.”
—Jeanne Elium (20th century)
“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)