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公开(公告)号：JP2001175370A
公开(公告)日：2001-06-29
申请号：JP2000311665
申请日：2000-10-12
Applicant: IBM
Inventor： GORDON J ROBINS , SENZIG DONALD NORMAN
Abstract: PROBLEM TO BE SOLVED: To design a processor chip so as to be provided with a unidirectional input/output bus or a bi-directional input/output bus to be optionally selected. SOLUTION: This processor is designed at a state that separate input bus and output bus are provided inside a chip. A gating network is coupled with the processor unidirectional buses so that the chip is provided with an alternative externally-wired bus structure. Only one set of bi-directional bus signal lines is wired outside the chip for the lowest cost and lowest performance. A true unidirectional bus is generated by gating the bi-directional bus so as to be a bus exclusive for device output and gating an alternative device input bus to a processor input bus for high performance operation in which high cost for high band width is justified. A bus enable signal line is wired at a proper state according to wired microprocessor bus structure.
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公开(公告)号：JPH11288411A
公开(公告)日：1999-10-19
申请号：JP892699
申请日：1999-01-18
Applicant: IBM
Inventor： SCHMOOKLER MARTIN STANLEY , SENZIG DONALD NORMAN
Abstract: PROBLEM TO BE SOLVED: To reduce the number of times of repetition by accurately estimating a square root, an inverse square root and a reciprocal by calculating an estimated reciprocal through subtracting the product of a normalized input value and a first constant from a second constant. SOLUTION: A full accuracy input (x) is divided into a high-order part xH and a low-order part xL, then the high-order part xH is sent to a look-up table(LUT) 200. The LUT 200 sends a first constant as an inclination to a booth multiplexer 202 and sends a second constant as an offset to a multiplier array/ adder 204. Then, the multiplier array/adder 204 calculates an estimated reciprocal by adding the product of one part of the normalized input value and the first constant to the second constant, or by subtracting that product from the second constant. Thus, a square root, an inverse square root and a reciprocal can be accurately estimated and the number of times of repetition can be reduced.
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公开(公告)号：SG72922A1
公开(公告)日：2000-05-23
申请号：SG1999000309
申请日：1999-02-01
Applicant: IBM
Inventor： SCHMOOKLER MARTIN STANLEY , SENZIG DONALD NORMAN
Abstract: An improved method of estimating the square root, reciprocal square root, and reciprocal of an input value in a computer system. The input value, after being normalized, is used to select a pair of constants from a table. The constants are based on a linear approximation of the function for each interval of the input value, offset to reduce a maximum error value for a given interval. The estimated function is calculated by adding or subtracting the product of a part of the normalized input value and the first constant from the second constant. In one implementation, the input value is normalized within the range 1 ≤ x
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