Three input arithmetic logic unit employing carry propagate logi

Details Three input arithmetic logic unit employing carry propagate logi Three input arithmetic logic unit employing carry propagate logi

1995-04-24

1996-02-20

Malzahn, David H.

Boots, shoes, and leggings

364787, G06F 750

Patent

active

054935245

ABSTRACT:
A three input arithmetic logic unit (230) forms a mixed arithmetic and Boolean combination of three multibit input signals. The current instruction drives an instruction decoder (250, 245) that generates functions signals F0-F7 which control the combination formed. The three input arithmetic logic unit (230) preferably employs a set of bit circuits (400), each forming carry propagate, generate and kill signals. These signals and a carry input produce a bit resultant and a carry output to the next bit circuit. Selection of the function signals enables the combination to be insensitive to one of the input signals, thus performing a two input function of remaining input signals. The instruction itself may include the function signals and function modification bits, or the function signals and function modification signals may be stored in a special data register. Function modification signals cause modification of the function signals prior to use. The three input arithmetic logic unit (230) includes a least significant bit carry-in generator (246) supplying a carry input to the least significant bit circuit (400). This carry input is determined by the combination being formed, and generally is "1" only during subtraction. The carry input may be specified in the special purpose data register (D0) for certain instructions.

REFERENCES:
patent: 3789206 (1974-01-01), Heightley
patent: 3983539 (1976-09-01), Faber et al.
patent: 4023023 (1977-05-01), Bourrez et al.
patent: 4037094 (1977-07-01), Vandierendonck
patent: 4125901 (1978-11-01), Merrow et al.
patent: 4225934 (1980-09-01), Nanderendonck
patent: 4439835 (1984-03-01), Best et al.
patent: 4467444 (1984-08-01), Harmon, Jr. et al.
patent: 4503511 (1985-03-01), Vandierendonck
patent: 4562537 (1985-12-01), Barnett et al.
patent: 4779210 (1988-10-01), Katsura et al.
patent: 4785393 (1988-11-01), Chu et al.
patent: 4905180 (1990-02-01), Kumar
patent: 4924422 (1990-05-01), Vassiliadis et al.
patent: 4933878 (1990-06-01), Guttag et al.
patent: 5140687 (1992-08-01), Dye et al.
patent: 5197140 (1993-03-01), Balmer
patent: 5210711 (1993-05-01), Rossmere et al.
patent: 5212777 (1993-05-01), Gove et al.
patent: 5226125 (1993-07-01), Balmer et al.
patent: 5231694 (1993-07-01), Novak et al.
patent: 5239654 (1993-08-01), Ing-Simmons et al.
patent: 5249266 (1993-09-01), Dye et al.
patent: 5301341 (1994-04-01), Vassiliadis et al.
Microprocessor Report, Slater, Michael, "IIT Ships Programmable Video Processor," vol. 5, No. 20 Oct. 30, 1991, pp. 1, 6-7, 13.

Affiliated with

Also associated with

Rating

Three input arithmetic logic unit employing carry propagate logi does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Three input arithmetic logic unit employing carry propagate logi, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Three input arithmetic logic unit employing carry propagate logi will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1361459