The Mudcat Café TM
Thread #59418   Message #2720038
Posted By: Amos
09-Sep-09 - 03:24 PM
Thread Name: BS: The Mother of all BS threads
Subject: RE: BS: The Mother of all BS threads
Rent's rule pertains to the organization of computing logic, specifically the relationship between the number of external signal connections to a logic block (i.e., the number of "pins") with the number of logic gates in the logic block, and has been applied to circuits ranging from small digital circuits to mainframe computers.

In the 1960's, E.F. Rent, an IBM employee, found a remarkable trend between the number of pins (terminals T) at the boundaries of integrated circuit designs at IBM and the number of internal components (g), such as logic gates or standard cells. On a log − log plot, these datapoints were on a straight line, implying a power-law relation T = tgp where t and p are constants (p < 1.0, and generally 0.5 < p < 0.8). Rent disclosed his findings in IBM-internal memoranda, but the relation was described in 1971 by Landman and Russo.[1] They performed a hierarchical circuit partitioning in such a way that at each hierarchical level (top-down) the least number of interconnections had to be cut to partition the circuit (in more or less equal parts). At each partitioning step, they noted the number of terminals and the number of components in each partition and then partitioned the sub-partitions further. They found the power law rule applied to the resulting T versus g plot and named it "Rent's rule". It is crucial to recognise that Rent's rule is an empirical result based on observations of existing designs, and therefore it is less applicable to the analysis of non-traditional circuit architectures. Having said that, it does provide a useful framework with which to compare similar architectures.

Once again, the power of Wikipedia shames the power of a normal library, counter-intuitive though that may be. Theorists explain that it is a function of primary and distributed R{x} elements in the informational hierarchy, where R is relative responsibility of the primary (first author) and secondary (administrators or additional authors) elements responsible for the distribution of information x through the network associated with the hierarchy.