Showing papers on "Routing (electronic design automation) published in 1969"

A solution to line routing problems on the continuous plane

Abstract: This paper discusses a new line-routing algorithm. The algorithm has been programmed in FORTRAN II for the IBM 7094 and in FORTRAN IV for the IBM 360/65. It has given good results when applied to many line-routing problems such as mazes, printed circuit boards, substrates, and PERT diagrams. The main advantages of this algorithm, which is based on the continuous plane, over conventional algorithms based on the discrete plane are twofold: 1. Since the algorithm is based on the continuous plane, there is theoretically no limit to the degree of precision used to describe the position of points. In practice, the only factor restricting the precision is the magnitude of the largest (or smallest) number which may be stored in a computer. As a result, the nodes on a printed circuit board, for example, can be input with mil accuracy. If this feat were to be accomplished by existing methods on a 9×9 inch board, a matrix of 81,000,000 cells would have to be stored (and searched) in the computer. 2. The algorithm stores only line segments; therefore to find a path, only the segments that are currently defined need be investigated. Usually with conventional methods, every cell that lies on every possible minimal path must be investigated. The net result is that this algorithm is much faster than the conventional method.

Optimum curvature principle in highway routing

Abstract: THIS ARTICLE CONSIDERS THE PROBLEM OF DETERMINING, FROM AMONGST ALL POSSIBLE ALTERNATIVES, THE OPTIMUM ROUTE TO CONNECT TWO CITIES. THE COMPUTER-BASED OPTIMUM CURVATURE PRINCIPLE (OCP) IS DERIVED FROM THE CALCULUS OF VARIATIONS, AND ITS PRACTICAL APPLICATION TO THE CRITERION FUNCTIONS OF HIGHWAY LOCATIONS IS DISCUSSED. /RRL/

Cellular wiring and the cellular modeling technique

Abstract: In cellular modeling a given structure is broken up into a collection of substructures called “cells.” Gross topology is then determined from the inter-cellular relation ships while only the essential intra cellular details are retained as parameters. Applying this method in printed circuit wiring programs results in dramatic savings in storage requirements and running times over conventional programs which consider each coordinate in their model. Storage requirements are reduced since only the inter-cellular wire routes are stored, Running time is shorter because one can determine when a wire is unroutable without computing the fine details of the routing. However, once the wiring is determined on the gross level, a significant problem remains—the overall routings must be transformed into specific coordinates with in each cell. The purpose of this paper is not to describe these programs, since they follow easily from the modeling technique, but rather to describe the ideas and concepts behind them.

Automated printed circuit routing with a stepping aperture

Abstract: A computer program for routing interconnections on a two-sided printed circuit board with a regular pattern of lines, pins (terminals), and vias (feed-through holes) is described.In this program, each interconnection is given a planned routing—typically, down from the upper pin, through a via, and horizontally to the lower pin. From the top, a virtual aperture (i.e. a long horizontal slit) is stepped down the board. The planned routing is the basis for rerouting interconnections within the aperture to resolve conflicts for lines and vias below the aperture and to maximize the effective line usage. If a conflict has not been resolved before the aperture arrives at the lower pin, interconnections are deleted to resolve the conflict.Extensions of this technique to the control of crosstalk between routed interconnections and to the problem of obtaining 100 percent interconnect are also discussed.

Traffic control for modifying the routing plan in a network of switching centers

Abstract: A communications network is disclosed wherein the code translation and routing apparatus at each switching center includes a memory having a number of code words and a number of routing words. Each code word stores a code which usually comprises three or six digits used in an associative search by comparison with the corresponding dialed digits. Each code word or group of code words is followed by one or three routing words, each of which designates one or more trunk groups, which may comprise a primary route and a number of alternate routes. Some of the code words include an automatic traffic control digit which directs which one of three routing words is to be used. The value of the traffic digit for each code or group of codes may be modified by a traffic controller by a call from a special station, to thereby designate which one of three predetermined routing plans stored in the respective routing words is to be used. Thus under abnormal traffic conditions caused, for example, by overloads in emergencies, or destruction of facilities, the traffic routing plan may be modified.

Simulation of a Computer Aided Routing System (CARS)

Abstract: CARS is s system designed to provide a taxi-like service at a mass transit-like cost. It allows potential passengers to request service from their via telephone, with calls being processed by a central computer facility. The computer periodically executes a routing algorithm which assigns vehicles to passengers and communicates this routing information to the vehicles. The system is 'real time' in that it will pick up a passenger and shortly after a request will deliver him to his destination within a guaranteed time (with a minimum number of deviations for collecting and delivering other passengers). The key to CARS is the routing algorithm. Since labor and vehicular costs are a major portion of the total system cost, an algorithm is required which can provide an effective dynamic service with a minimum number of vehicles. A variety of such algorithms have been proposed, but these algorithms can not be evaluated in an analytic fashion. Hence, a comprehensive simulation model has been developed to test and compare these routing algorithms. The model facilitates the investigation of relationships between such parameters as number of vehicles and quality of service. This paper describes the methodology of the simulation model and the economic gains (in terms of the need for fewer vehicles) realized through its use. The use of an ARDS storage tube display to produce graphical output from the model is also discussed.

Optimum Routing Strategies for Noisy Communication Networks

Abstract: In this paper we study optimum routing strategies that minimize the degrading effects of system noise in noisy communication networks. Previous papers have treated problems related to finding an optimum single communication path through a network; we consider the problem of establishing several communication paths simultaneously. Networks with fixed link characteristics and networks with links that may adapt their number of channels to traffic requirements are considered. Primary emphasis is on digital communication networks, but it is also pointed out that the same techniques can be used for a certain class of linear, continuous signal networks. Using the concepts of information measure from information theory, we discuss the maximization of information transfer in a communication network. We also treat the problem of finding the maximum number of channel paths with signal transmission capabilities better than some lower bound, and the problem of finding k channel paths that minimize the use of the poorest paths.

Printing means for sorting and routing system

Abstract: A printing means of a type adapted to simultaneously print ordinary legible indicia and corresponding magnetic ink characters upon a label in which the activating for magnetic character operation is made by the presence of a label in a particular location upon a platen, whereby an electrical circuit is closed through a predetermined opening in said label.

Dynamic Communication Networks with Capacity Constraints

Abstract: Communication networks with link transit times are modeled by linear graphs with branch time delays and finite branch capacities. Memoryless linear routing strategies as well as linear routing strategies with finite memory are defined. The state reachability problem in both cases is considered, and the sets of reachable demand vectors are exhibited. The problem of finding optimal routings which minimize network losses subject to demand constraints is formulated as a linear program, and extensions to infinite memory and time-varying systems are given.

Routing device with movable routing tool

Abstract: Routing devices that can conveniently, quickly and efficiently cause door panels, or the like, to be slotted on a mass production basis for purposes of associating hinges therewith that require slots formed in the panels. The routing tools are movable and the panels are held stationary.

Routing device with stationary routing tool

Abstract: Routing devices that can conveniently and quickly cause door panels, or the like, to be slotted on a mass production basis for purposes of associating hinges therewith that require slots formed in the panels. The routing tools thereof are held stationary and the panels are fed toward the routing tools.

Routing techniques for distributed communica

Abstract: The concept of a netted or distributed communications system is significant because it offers a major advantage over conventional communications systems, i.e., a better chance of pro- viding surviving lines of communication after an attack on the sys- tem. During and after an attack, however, an effective adaptive routing technique is necessary to adjust the routing tables of the message-switching controi system to the changing situation. Pre- vious:y investigated adaptive routing techniques are shown to be insufficient for the task, and a number of promising alternatives are formulated and investigated such as some stochastic techniques, which use information on messages passing through the network to adjust the tables, and some deterministic techniques, which use dynamic programming or graph-theoretic algorithms to recalculate changes in the tables from observed changes in the network. Each alternative has operational advantages, which make it good for certain types of communications systems, and certain disadvantages if applied to others. Regions of applicability and inapplicability, with respect to the above system parameters, are given for the various techniques. Recommended techniques are specified for two currently proposed applications of distributed communications sys- tems. A number of research areas are pointed out in which further efforts in the analysis and simulation of adaptive routing techniques will have useful payoffs in the design of future distributed com- munications systems.

Aw expanded logic equation list for checkout

Abstract: In the computer-aided design of digital equipment, by the time a wire unit is in the check-out lab, a large amount of information concerning this unit exists in the form of tape files. Since our D.A. System is entered via logic equations, we have a file containing this information, plus files indicating the partitioning of the equations, the placement of smaller building blocks within larger building blocks, and the assignment of signals to pins for routing or wiring. Also, there will be a wire list file (or a router output file) plus a punch card deck when a wiring machine is to be used. In addition a large pile of computer output reports will exist communicating this information to the literate world. About two years ago we learned that in some of the checkout labs engineers were devoting large amounts of time pouring through the reports we generate in order to correlate signals appearing in logic equations with connector pins. In order to remove this burden from these engineers, a program known as the Equation Connector Program (EQNCON) was written. This program exhibits the correlation of logic signals and connector pins in a printed report which is then heavily used during checkout.

Minimizing system delay in synchronous digital backplane designs

Abstract: A given placement, interconnection and routing of modules and wires of a backboard design of a synchronous digital system places an upper bound on the associated clock speed. This bound is the “system delay”, i.e., the longest delay path from a flip-flop output to a flip-flop input. The SD algorithm makes the placement, interconnection (but not routing) decision to give a design with a system delay close to the lower bound. A solution of a modified form of the “classical” Steinberg 34 module problem is compared with other published results. Extrapolation indicates that significant reduction in system delay can also be obtained with practical designs in reasonable computing time.