US3761881A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Translation storage scheme for virtual memory system
Assignee: International Business Machines Corp
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Filing: 1971-06-30
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Granted: 1973-09-25
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Expires: 1991-06-30
Abstract
Abstract A virtual memory system comprising a main storage and a smaller high speed buffer. Both main storage and the buffer are realaddress-oriented. Current virtual-to-real address translations are retained in a Translation Look Aside Table (TLAT) and real addresses of data stored in the buffer are maintained in a buffer directory. The CPU-provided virtual address causes access to the TLAT and to the buffer directory. The virtual address stored in the word accessed from the TLAT is compared to the virtual address from the CPU and the real addresses accessed from the TLAT and the buffer directory are compared to each other. If both comparisons are equal, the data is accessed from the buffer.
Inventors
- 👤 D Anderson
- 👤 R Gustafson
- 👤 P Kaminsky
- 👤 J Wetzel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 19:49
CPC Classifications
G; G06; G06F; G06F12/00; G06F12/02; G06F12/08; G06F12/10; G06F12/1027; G06F12/1045; G06F12/1054
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
271 words
In a data processing system which contains a central processing unit, a main storage having n addressable locations each addressable by a real storage address, a buffer storage having fewer than n addressable locations each addressable by a real storage address, addressing means providing virtual addresses each having a virtual portion which is made up of bits that do not constitute a portion of a real storage address and a real displacement which is made up of address bits that constitute a portion of a real storage address, and translation table means for translating the virtual portions of the virtual addresses to real address portions other than said real displacement, an improved translation storage means responsive to said virtual addresses comprising: first table means storing a plurality of real addresses of data contained in main storage, said plurality each having been translated from a corresponding virtual portion by said translation table means; second table means storing a plurality of real addresses of data stored in the buffer storage; means responsive to a virtual portion received by said translation storage means to cause a real address related to said virtual portion to be read from said first table means; means jointly responsive to part of said virtual portion and to the real displacement received by said translation storage means to cause a real address related thereto to be read from said second Table means; means for comparing an address read from said first table means to an address read from said second table means; and means responsive to an equal compare to indicate that the addressed data is in said buffer storage.
Claim 2
Dependent Claim
271 words
In a data processing system which contains a central processing unit, a main storage having n addressable locations each addressable by a real storage address, a buffer storage having fewer than n addressable locations each addressable by a real storage address, addressing means providing virtual addresses each having a virtual portion which is made up of bits that do not constitute a portion of a real storage address and a real displacement which is made up of address bits that constitute a portion of a real storage address, and translation table means for translating the virtual portions of the virtual addresses to real address portions other than said real displacement, an improved translation storage means responsive to said virtual addresses comprising: first table means storing a plurality of real addresses of data contained in main storage, said plurality each having been translated from a corresponding virtual portion by said translation table means; second table means storing a plurality of real addresses of data stored in the buffer storage; means responsive to a virtual portion received by said translation storage means to cause a real address related to said virtual portion to be read from said first table means; means jointly responsive to part of said virtual portion and to the real displacement received by said translation storage means to cause a real address related thereto to be read from said second Table means; means for comparing an address read from said first table means to an address read from said second table means; and means responsive to an equal compare to indicate that the addressed data is in said buffer storage.
Claim 3
Dependent Claim
31 words
The storage control means of claim 1 further including means responsive to said indication that the addressed data is in said buffer storage to initiate an access to said buffer storage.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-24 | 1977-03-26 | 1977-09-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-24 | 1981-03-26 | 1981-09-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-24 | 1985-03-26 | 1985-09-25 | $7700.00 | Window Closed / Lapsed |