GB1535091A - Manufacture of electronic circuits - Google Patents

Abstract

1535091 Computer-aided circuit design INTERNATIONAL COMPUTERS Ltd 29 April 1977 [15 May 1976] 20149/76 Heading G4A Electronic devices and associated horizontal and vertical conductors are assigned initial positions with respect to a notional grid of cells (there being no restriction on the number of conductors passing through each cell). The computer is programmed to process in turn each row (column) of cells perpendicular to a first grid axis to assign to each device and conductor in that row (column) a first axis co-ordinate having a minimum value consistent with spacing constraints imposed in respect of other devices and conductors to which co-ordinates have been assigned previously. Each column (row) of cells perpendicular to the other grid axis is then processed in turn by the computer to assign minimum value second axis coordinates, consistent with the spacing constraints, to the devices and conductors. The method has greater flexibility than known methods in which the positions of the devices are fixed first and then the connections are routed. The cell size may be chosen so that each device (of variable size) occupies an approximately whole number of cells. The co-ordinate increments may be equal to the minimum possible spacing between devices/conductors. The method is applicable to integrated circuits, microwired circuits and printed circuits. The computer preferably has a main store and a backing (disc) store holding a working file of details of devices and conductors, details for the row or column currently being processed being held in the main store. The conductors in each row or column are preferably arranged in priority order of length for processing in that order, and priority in processing may also be given to conductors and devices which, when placed, prevent another device or conductor being assigned a lower co-ordinate value than itself.