History
The IBM SSEC, demonstrated in January 1948, had the ability to modify its instructions or otherwise treat them exactly like data. However, the capability was rarely used in practice. In the early days of computers, self-modifying code was often used to reduce use of limited memory, or improve performance, or both. It was also sometimes used to implement subroutine calls and returns when the instruction set only provided simple branching or skipping instructions to vary the control flow. This use is still relevant in certain ultra-RISC architectures, at least theoretically; see for example one instruction set computer. Donald Knuth's MIX architecture also used self-modifying code to implement subroutine calls.
Read more about this topic: Self-modifying Code
Famous quotes containing the word history:
“[Men say:] “Don’t you know that we are your natural protectors?” But what is a woman afraid of on a lonely road after dark? The bears and wolves are all gone; there is nothing to be afraid of now but our natural protectors.”
—Frances A. Griffin, U.S. suffragist. As quoted in History of Woman Suffrage, vol. 4, ch. 19, by Susan B. Anthony and Ida Husted Harper (1902)
“... that there is no other way,
That the history of creation proceeds according to
Stringent laws, and that things
Do get done in this way, but never the things
We set out to accomplish and wanted so desperately
To see come into being.”
—John Ashbery (b. 1927)
“If usually the “present age” is no very long time, still, at our pleasure, or in the service of some such unity of meaning as the history of civilization, or the study of geology, may suggest, we may conceive the present as extending over many centuries, or over a hundred thousand years.”
—Josiah Royce (1855–1916)