公开(公告)号：DE1203504B

公开(公告)日：1965-10-21

申请号：DEJ0024672

申请日：1963-11-02

Applicant: IBM

Inventor： OTTAWY GERALD HOWARD ,  BOLAND LAWRENCE JOSEPH ,  BLAAUW GERRIT ANNE ,  KESLIN ROBERT

IPC: G06F7/491 ,  G06F7/52

Abstract: 1,049,680. Digital computers; division. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 5, 1963 [Nov. 5, 1962], No. 43554/63. Heading G4A. Division is performed by a trial-and-error method. A quotient is guessed and multiplied by the divisor in unit 10 the result being subtracted from the dividend. The quotient is used to address, through circuit 3, a table lookup device which reads out a higher (or equal) and lower quotient for the next try. If there is a carry out of the subtraction unit the higher quotient becomes the next guess, if not the lower quotient is used. The process is continued until the quotients in registers 5 and 6 are one even and one odd. Whichever of these is used is then the required answer and is transferred to register 14. The result of the subtraction is then the remainder and is transferred to the dividend register 1. If the radix is 16 the initial quotient could be 8 and the first pair of quotients selected are 4 and 12. If the radix is 10 the initial quotient could be 4 and the first pair of quotients 2 and 6. The detection of the highest order out-carry can be by means of carry-look-ahead apparatus.