Memory device which can function as two separate memories or a single memory
First Claim
1. A memory device comprising:
- first data storage means having n locations for storing n words of data, where n is an integer greater than one;
second data storage means having m locations for storing m words of data, where m is an integer greater than one; and
control means for functioning in one of a first mode and a second mode, said control means receiving a first set of words of data and storing said first set of words of data in sequential locations within said first data storage means when said control means is in said first mode, said control means receiving a second set of words of data and storing said second set of words of data in sequential locations within said second data storage means when said control means is in said first mode, said control means providing data stored in said sequential locations within said first and second data storage means, thereby causing said first and second data storage means to function as an n location FIFO memory and an m location FIFO memory, respectively, when said control means is in said first mode, said control means storing a third set of words of data in sequential locations within said first data storage means and then storing words of data within said third set in sequential locations within said second data storage means after storing data in the last location in said first data storage means when said control means is in said second mode, said control means providing data stored in sequential locations within said first data storage means and then providing data stored in sequential locations within said second data storage means after providing data stored in the last location of said first data storage means when said control means is in said second mode, thereby causing said first and second data storage means to function as a single n+m location FIFO memory.
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Accused Products
Abstract
A FIFO memory device facilitates transfer of data between a host CPU and a peripheral device in one of a number of modes. In one mode, the FIFO memory device functions as two FIFO memories, one for passing data from the host CPU to the peripheral device, and one for passing data to the host CPU from the peripheral device. In another mode, the FIFO memory device functions as a single FIFO which facilitates passing data from the host CPU to the peripheral device or from the peripheral device to the host CPU. The FIFO incloudes two RAMs addressed by a set of address counters. Of importance, the host CPU can bypass the address counters to directly address each RAM, thereby reading data from or writing data into either RAM regardless of the state of the address counters.
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Citations
8 Claims
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1. A memory device comprising:
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first data storage means having n locations for storing n words of data, where n is an integer greater than one; second data storage means having m locations for storing m words of data, where m is an integer greater than one; and control means for functioning in one of a first mode and a second mode, said control means receiving a first set of words of data and storing said first set of words of data in sequential locations within said first data storage means when said control means is in said first mode, said control means receiving a second set of words of data and storing said second set of words of data in sequential locations within said second data storage means when said control means is in said first mode, said control means providing data stored in said sequential locations within said first and second data storage means, thereby causing said first and second data storage means to function as an n location FIFO memory and an m location FIFO memory, respectively, when said control means is in said first mode, said control means storing a third set of words of data in sequential locations within said first data storage means and then storing words of data within said third set in sequential locations within said second data storage means after storing data in the last location in said first data storage means when said control means is in said second mode, said control means providing data stored in sequential locations within said first data storage means and then providing data stored in sequential locations within said second data storage means after providing data stored in the last location of said first data storage means when said control means is in said second mode, thereby causing said first and second data storage means to function as a single n+m location FIFO memory. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A memory device comprising:
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first data storage means having n locations for storing n words of data, where n is an integer greater than one; second data storage means having m locations for storing m words of data, where m is an integer greater than one; and control means for functioning in one of a first mode and a second mode, said control means receiving a first set of words of data and storing said first set of words of data in sequential locations within said first data storage means when said control means is in said first mode, said control means receiving a second set of words of data and storing said second set of words of data in sequential locations within said second data storage means when said control means is in said first mode, said control means providing data stored in said sequential locations within said first and second data storage means, thereby causing said first and second data storage means to function as an n location last-in-first-out memory and an m location last-in-first-out memory, respectively, when said control means is in said first mode, said control means storing a third set of words of data in sequential locations within said first data storage means and then storing words of data within said third set in sequential locations within said second data storage means after storing data in the last location in said first data storage means when said control means is in said second mode, said control means providing data stored in sequential locations within said first and second data storage means on a last-in-first-out basis when said control means is in said second mode, thereby causing said first and second data storage means to function as a single n+m location last-in-first-out memory.
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Specification