Shmoo plot: Difference between revisions

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Added that shmooing was current in late 1960s/70s to refer to "tweaking" ferrite core memory stacks, which puts in doubt the story of the originator.
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In [[electrical engineering]], a '''shmoo plot''' is a graphical display of the response of a component or system varying over a range of conditions and inputs. Often used to represent the results of the testing of complex electronic systems such as computers or integrated circuits such as [[DRAM]]s, ASICs or microprocessors. The plot usually shows the range of conditions in which the [[device under test]] operates (in adherence with some remaining set of specifications). The term was in use in 1970 to refer to the "tuning" of ferrite core memory stacks on IBM systems.
 
For example, when testing [[semiconductor]] [[memory]]: [[voltage]]s, [[temperature]], and [[refresh rate]]s can be varied over specified ranges and only certain combinations of these factors will allow the device to operate. Plotted on independent axes (voltage, temperature, refresh rates), the range of working values will enclose a three-dimensional, usually oddly-shaped volume. Other examples of conditions and inputs that can be varied include [[frequency]], [[temperature]], timing parameters, system- or component-specific variables, and even varying knobs tweakable during [[silicon chip fabrication]] producing parts of varying quality which are then used in the process.