Hardware-software counting
AssigneeInternational Business Machines Corporation
InventorWilliam Henry Ashbee
Life of this patent
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Abstract
A hardware counter counts high rate, lower significant bits. A carry-borrow circuit responsive to the higher order bit position of the hardware counter includes cancel means responsive to successively received carry and borrow signals to cancel previously generated carries or borrows. Memory means in the carry-borrow circuit memorize the generation of the carry or borrow by the hardware counter. A programmed microprocessor, or the like, periodically senses the status of the carry-borrow circuit for transferring signal contents thereof to a software controlled count field. The arrangement permits high speed counting without interrupting the microprocessor and not imposing rate constraints on program execution of the microprocessor.
Claims8
A hardware-software counter comprising a hardware counter for counting lower significant bits, a carry-borrow circuit responsive to a higher order bit position of said counter and including cancel means responsive to successively received carry and borrow signals to cancel a respectively represented carry and borrow, memory means in the carry-borrow circuit separately memorizing a received carry or borrow, means responsive to said memory means to deactivate said cancel means, and a microprocessor including an adder for counting higher significant bits and means in said microprocessor for sensing said memory means in said carry-borrow circuit for determining whether a "1" is to be added to said higher significant bits.
A programmable machine controller, including in combination:
- tachometer circuit means for indicating operational status of a machine to be controlled,
- a hardware up/down counter connected to said tachometer circuit means and responsive thereto to establish a count indicative of a cumulative status of said machine being controlled,
- a microprocessor including an adder and a memory for controlling said machine, and
- means coupling said up/down counter to said microprocessor for supplying count signals thereto, including count preservation means for obviating the need for interrupting said microprocessor to capture a count related to the machine to be controlled.
Dependencies are inferred from the claim text.