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System for interpreting Rent's Rule for ultralarge-scale integrated circuit designs

IP.com Disclosure Number: IPCOM000019240D
Original Publication Date: 2003-Sep-08
Included in the Prior Art Database: 2003-Sep-08
Document File: 7 page(s) / 244K

Publishing Venue

IBM

Abstract

Computer hardware components have changed significantly since the 1960's, 1970's, 1980's, and even since the early 1990's. Work concerning Rent's Rule prior to the present paper has been based on a 1971 interpretation of two unpublished memoranda written in 1960 by E. F. Rent at IBM, even though today's computer components are significantly different from those in 1960 and 1971. However, because of the significant changes in design and implementation of computer hardware components since 1960-1971, a new interpretation of Rent's Rule is needed for today's components. The authors have obtained copies of Rent's two memos; in these 1960 memos, E. F. Rent describes the method that he used to deduce an empirical relationship between properties of IBM 1401 and 1410 computer hardware components. The authors have studied these memos carefully in order to understand Rent's original intent. Based on our careful reading of these two memos, the personal knowledge of one of us (R. Rand) with the 1401 and 1410 computers, and our experience with ULSI circuit design for high-performance microprocessors, the authors have derived an historically-equivalent interpretation of Rent's Rule suitable for today's computer components. The purpose of this disclosure is to present this new interpretation of Rent's Rule and its application to wirelength distributions of ultralarge-scale integrated (ULSI) circuits. This disclosure will: (1) describe the contents of the memos and Rent's method, (2) provide an historically-equivalent interpretation of Rent's Rule for today's computer components, and (3) apply this new interpretation to actual ULSI circuit designs. This new interpretation provides improved wirelength distribution models with better qualitative agreement and more accurate estimates of wirelength distributions and wirelength requirements in ULSI designs compared with prior methods.

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Page 1 of 7

System for interpreting Rent's Rule for ultralarge-scale integrated circuit designs

The authors have obtained copies of both of E. F. Rent's IBM
memoranda dated November 28, 1960 and December 12,
1960, and have studied these memos in order to understand the
method that E. F. Rent employed to analyze characteristics of the
IBM
$1401$ and $1410$ computers. In these memos, Rent describes the
method that he used to deduce an empirical relationship between
properties of computer hardware components of these computers.
Based
on a careful reading of these two memos, the personal knowledge
of
one of us (R. Rand) with the 1401 and 1410 computers, and our
experience designing and wiring ULSI circuits for
high-performance
microprocessors, the authors have derived an
historically-equivalent
interpretation of Rent's Rule suitable for today's computer
components.

This disclosure describes an historically-equivalent
interpretation of
Rent's Rule suitable for today's ULSI circuit designs. The
contributions of this disclosure are: (1) a description of the
contents of
the two memoranda and Rent's method; and (2) an
historically-equivalent
interpretation of Rent's Rule suitable for today's computer
components. The information provided in this disclosure provides
distributions and average wirelength estimates that are improved
compared with current models. The
information provided in this disclosure provides circuit
designers with a new method to evaluate the amount and
distribution of wire required to interconnect
components in ULSI systems in order to achieve buildable and
functional chip designs within increasingly severe project
constraints
of real estate, number of metal layers, operating frequency, and
power
dissipation.

This disclosure describes the present understanding the two
memoranda written by E. F. Rent and dated November 28, 1960 and
December 12, 1960. Described are: Rent's memoranda and the method
that Rent used to analyze components of the 1410 and 1401, two
computers introduced by IBM in 1959-1960. The 1410 computer was
an

1

Page 2 of 7

IBM IO processor that read in punch cards and output computing
results


Components of 1410 and 1401 computer hardware discussed by Rent
in his
memos are: the computer chassis, card, circuit
count, and edge connector count. The computer chassis
contains several cards that are connected together in the
chassis. Each card is composed of one or more circuits; the
circuits
on the card can either be used or unused; used circuits are
connected
to used circuits on other cards within the chassis with the use
of
edge connectors. A circuit is also referred to as a logic
block. Figure 1 shows a schematic
depiction prepared by the present authors of the computer
components
described in E. F. Rent's two memos. This figure shows (a) a
schematic
of a design, including a computer chassis and cards (e.g., card
A),
and (b) a card, circuit, edge connectors, used circuit, and
unused
circuit.

Fig.1

2

Page 3 of 7

In the first memo, Rent describes his method to o...