Modern Uses of The Modified Harvard Architecture
Outside of applications where a cacheless DSP or microcontroller is required, most modern processors have a CPU cache which partitions instruction and data.
There are also processors which are Harvard machines by the most rigorous definition (that program and data memory occupy different address spaces), and are only modified in the weak sense that there are operations to read and/or write program memory as data. For example, LPM (Load Program Memory) and SPM (Store Program Memory) instructions in the Atmel AVR implement such a modification. Similar solutions are found in other microcontrollers such as the PIC and Z8Encore!, many families of digital signal processors such as the TI C55x cores, and more. Because instruction execution is still restricted to the program address space, these processors are very unlike von Neumann machines.
Having separate address spaces creates certain difficulties in programming with high-level languages such as C, which don't directly support the notion that tables of read-only data might be in a different address space from normal writable data (and thus need to be read using different instructions).
Read more about this topic: Modified Harvard Architecture
Famous quotes containing the words modern, modified, harvard and/or architecture:
“The modern nose, like the modern eye, has developed a sort of microscopic, intercellular intensity which makes our human contacts painful and revolting.”
—Marshall McLuhan (1911–1980)
“Poetry presents indivisible wholes of human consciousness, modified and ordered by the stringent requirements of form. Prose, aiming at a definite and concrete goal, generally suppresses everything inessential to its purpose; poetry, existing only to exhibit itself as an aesthetic object, aims only at completeness and perfection of form.”
—Richard Harter Fogle, U.S. critic, educator. The Imagery of Keats and Shelley, ch. 1, University of North Carolina Press (1949)
“As a medium of exchange,... worrying regulates intimacy, and it is often an appropriate response to ordinary demands that begin to feel excessive. But from a modernized Freudian view, worrying—as a reflex response to demand—never puts the self or the objects of its interest into question, and that is precisely its function in psychic life. It domesticates self-doubt.”
—Adam Phillips, British child psychoanalyst. “Worrying and Its Discontents,” in On Kissing, Tickling, and Being Bored, p. 58, Harvard University Press (1993)
“The two elements the traveler first captures in the big city are extrahuman architecture and furious rhythm. Geometry and anguish. At first glance, the rhythm may be confused with gaiety, but when you look more closely at the mechanism of social life and the painful slavery of both men and machines, you see that it is nothing but a kind of typical, empty anguish that makes even crime and gangs forgivable means of escape.”
—Federico García Lorca (1898–1936)