Patent US2626553A successfully refreshed from Google Patents.
US3810129A
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US
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Memory system restoration
Assignee: International Business Machines Corp
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Filing: 1972-10-19
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Granted: 1974-05-07
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Expires: 1992-10-19
Abstract
Abstract Restoration of information in a memory of the type requiring periodic restoration to maintain viability of the information is carried out in a manner dependent on the relative need of memory cells in the memory for restoration. This system includes an array of memory cells in which the stored information must be restored periodically to maintain its viability. Means for accessing the memory cells in the array desirably accomplishes a restoration of a memory cell each time it is accessed. Means for determining a priority list of the memory cells in the array for restoration does so in an order substantially dependent on the relative need of the memory cells for restoration. Means are provided for restoring the memory cells sequentially in the absence of a requested access to the memory array in accordance with the priority list established by the priority list determining means. In this manner, a memory requiring, e.g., 50 percent of its operating time for restoration may be available 90 or even 100 percent of the time a requested access is made.
Inventors
- 👤 S Behman
- 👤 S Goldstein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:18
CPC Classifications
G; G11; G11C; G11C11/00; G11C11/21; G11C11/34; G11C11/40; G11C11/401; G11C11/406
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
103 words
A memory system comprising: A. a plurality of memory units in which stored information must be restored within a predetermined time period to maintain information viability; B. accessing means for accessing said memory units, said memory units being restored when accessed; C. priority determining means for determining a restoration priority for restoring said memory units in an order substantially dependent on the frequency of access of the memory units; and D. restoration means for automatically restoring the memory units sequentially in the absence of a requested access to any of said memory units in accordance with the priority of said priority determining means.
Claim 2
Dependent Claim
103 words
A memory system comprising: A. a plurality of memory units in which stored information must be restored within a predetermined time period to maintain information viability; B. accessing means for accessing said memory units, said memory units being restored when accessed; C. priority determining means for determining a restoration priority for restoring said memory units in an order substantially dependent on the frequency of access of the memory units; and D. restoration means for automatically restoring the memory units sequentially in the absence of a requested access to any of said memory units in accordance with the priority of said priority determining means.
Claim 3
Dependent Claim
18 words
The memory system of claim 1 in which the memory units of said array comprise capacitive storage elements.
Claim 4
Dependent Claim
18 words
The memory system of claim 2 in which the capacitive storage elements are gated by field effect transistors.
Claim 5
Dependent Claim
110 words
The memory system of claim 1 wherein said priority determining means includes a priority memory for retaining an indication of the number of times each memory unit has been restored within the last M memory cycles, where M is greater than the number of storage units, the first memory units to be sequentially restored being determined by sequentially scanning through the contents of said priority memory,, said priority determining means determining priority on the basis that all memory units that have been accessed only once have priority for restoration, and, in the absence of only once accessed memory units, the memory unit restored M cycles ago has priority for restoration.
Claim 6
Dependent Claim
161 words
The memory system of claim 1 in which said priority determining means includes a restoration memory which stores a restoration history of said memory system for the preceding M memory cycles, M being greater than the number of memory units and being the number of cycles corresponding to the predetermined time period information may be stored in said memory system without restoration and a restoration pointer for sequentially indicating the memory unit to be restored next, and said restoration means delaying a restoration to a later non-access cycle in favor of a requested access in a given cycle unless the memory unit indicated by said restoration pointer must be restored during said given cycle, said delay being effected on the condition that a restoration was not carried out M cycles ago and that the number of cycles indicated by the restoration memory, in which a restoration was not performed, equals the difference between M cycles and the number of memory units.
Claim 7
Dependent Claim
94 words
In a memory of the type in which information must be periodically restored in order to maintain its viability, the improvement comprising: A. means for determining the restoration priority of sequentially arranged memory cells in an array of said memory in an order substantially corresponding to the frequency of access of said memory cells during a predetermined period of time, said memory cells being automatically restored when accessed; and B. means for sequentially restoring said memory cells in the absence of a requested access in accordance with the priority of said priority determining means.
Claim 8
Dependent Claim
94 words
In a memory of the type in which information must be periodically restored in order to maintain its viability, the improvement comprising: A. means for determining the restoration priority of sequentially arranged memory cells in an array of said memory in an order substantially corresponding to the frequency of access of said memory cells during a predetermined period of time, said memory cells being automatically restored when accessed; and B. means for sequentially restoring said memory cells in the absence of a requested access in accordance with the priority of said priority determining means.
Claim 9
Dependent Claim
19 words
The memory of claim 6 in which the memory cells comprise capacitive storage elements gated by field effect transistors.
Claim 10
Dependent Claim
94 words
A process for operating a memory in which information mUst be periodically restored in order to maintain its viability, comprising: A. establishing a priority of memory cells in said memory for restoration, substantially in accordance with the frequency of access of the memory cells, B. restoring each cell of said memory each time an access to the cell is made, C. restoring cells of said memory in accordance with the priority in time intervals in the absence of an access to the memory, and D. updating the priority on the basis of each restoration.
Claim 11
Dependent Claim
94 words
A process for operating a memory in which information mUst be periodically restored in order to maintain its viability, comprising: A. establishing a priority of memory cells in said memory for restoration, substantially in accordance with the frequency of access of the memory cells, B. restoring each cell of said memory each time an access to the cell is made, C. restoring cells of said memory in accordance with the priority in time intervals in the absence of an access to the memory, and D. updating the priority on the basis of each restoration.
Claim 12
Dependent Claim
64 words
The process of claim 8 additionally comprising: E. inhibiting access to a memory cell during a time interval when the priority indicates that a different memory cell not restored by the access requires restoration in order to avoid risking loss of information in it, F. restoring the different memory cell during that time interval, and G. allowing the access in a subsequent time interval.
Claim 13
Dependent Claim
69 words
The process of claim 9 in which the highest priority for restoration is established for the least recently accessed of those memory cells only once accessed in the previous number of cycles information may be stored in the memory cells without restoration, and, in the absence of only once accessed memory cells, the highest priority for restoration is established for the memory cells restored that number of cycles ago.
References Cited (Backward Citations)
US3737879A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-05-06 | 1977-11-05 | 1978-05-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-06 | 1981-11-05 | 1982-05-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-06 | 1985-11-05 | 1986-05-07 | $7700.00 | Window Closed / Lapsed |