US4435756A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Branch predicting computer
Assignee: Unisys Corp
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Filing: 1981-12-03
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Granted: 1984-03-06
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Expires: 2001-12-03
Abstract
Abstract Disclosed is a digital computer which includes means for storing a plurality of instructions arranged as a program with conditional branch instructions at respective locations in said program specifying conditions to be tested; an instruction prefetch means and an instruction execute means for respectively fetching and executing different instructions of said program at the same time in a pipelined fashion; said conditional branch instruction at each of said locations further having multiple encodings which predict the state of the condition to be tested; and a control means for detecting when said prefetch means has fetched one of said conditional branch instructions and for fetching the next instruction based on the predicted state of the condition to be tested and encoded in said fetched conditional branch instruction.
Inventors
- 👤 Hanan Potash
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 00:26
CPC Classifications
G; G06; G06F; G06F9/00; G06F9/06; G06F9/30; G06F9/30094; G06F9/38; G06F9/3836; G06F9/3842; G06F9/3844; G06F9/3846
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
126 words
An improved digital device including a memory means for storing a plurality of instructions arranged as a program with conditional branch instructions at respective locations in said program specifying conditions to be tested; an instruction prefetch means and an instruction execute means for respectively fetching and executing different instructions of said program at the same time in a pipelined fashion; said conditional branch instruction at each of said locations further having multiple encodings which predict the state of the condition to be tested; and a control means for detecting when said prefetch means has fetched one of said conditional branch instructions and for fetching the next instruction based on the predicted state of the condition to be tested and encoded in said fetched conditional branch instruction.
Claim 2
Dependent Claim
126 words
An improved digital device including a memory means for storing a plurality of instructions arranged as a program with conditional branch instructions at respective locations in said program specifying conditions to be tested; an instruction prefetch means and an instruction execute means for respectively fetching and executing different instructions of said program at the same time in a pipelined fashion; said conditional branch instruction at each of said locations further having multiple encodings which predict the state of the condition to be tested; and a control means for detecting when said prefetch means has fetched one of said conditional branch instructions and for fetching the next instruction based on the predicted state of the condition to be tested and encoded in said fetched conditional branch instruction.
Claim 3
Dependent Claim
70 words
A device according to claim 1 and further including a writing means for changing said encoding of said fetched conditional branch instruction at its memory location in a predetermined fashion in response to that instruction having an encoding which predicts a state of said condition that is different than the actual state of said condition at the time when that instruction is executed in said pipeline by said execute means.
Claim 4
Dependent Claim
49 words
A device according to claim 1 and further including means for detecting other encodings of said fetched conditional branch instruction which give a history of how said predicted state of said condition compared with the actual state of said condition during previous executions of the fetched conditional branch instruction.
Claim 5
Dependent Claim
70 words
A device according to claim 3 and further including a writing means for changing the encoding of said fetched conditional branch instruction in a predetermined fashion at its memory location in response to said means for detecting having detected that the predicted state of said condition was different than the actual state of said another condition the last time said fetched conditional branch instruction was executed by said execute means.
Claim 6
Dependent Claim
25 words
A device according to claim 1 wherein said conditional branch instruction has an operation code, and said multiple encodings are encodings of said operation code.
Claim 7
Dependent Claim
21 words
A device according to claim 5 wherein said encodings of said operation code of said conditional branch instruction are binary encodings.
Claim 8
Dependent Claim
13 words
A device according to claim 1 wherein said device is a digital computer.
Claim 9
Dependent Claim
116 words
A programmable digital device including a memory means for storing a plurality of instructions arranged as a program; a conditional branch instruction at one location in said program having a first encoding specifying a condition to be tested and predicting a first state of said condition; another conditional branch instruction at another location in said program having a second encoding specifying said same condition to be tested and predicting a second state of said condition; and a means for fetching said conditional branch instruction from any one of said locations and for thereafter fetching the next instruction from said program based on said predicted state of said condition as encoded in said fetched conditional branch instruction.
Claim 10
Dependent Claim
116 words
A programmable digital device including a memory means for storing a plurality of instructions arranged as a program; a conditional branch instruction at one location in said program having a first encoding specifying a condition to be tested and predicting a first state of said condition; another conditional branch instruction at another location in said program having a second encoding specifying said same condition to be tested and predicting a second state of said condition; and a means for fetching said conditional branch instruction from any one of said locations and for thereafter fetching the next instruction from said program based on said predicted state of said condition as encoded in said fetched conditional branch instruction.
Claim 11
Dependent Claim
68 words
A programmed digital device including a memory means for storing a plurality of instructions arranged as a program; at least one of said instructions being a conditional branch instruction specifying a condition to be tested; said at least one conditional branch instruction having at least a first encoding predicting a first state of said condition and having at least a second encoding predicting a second state of condition.
Claim 12
Dependent Claim
68 words
A programmed digital device including a memory means for storing a plurality of instructions arranged as a program; at least one of said instructions being a conditional branch instruction specifying a condition to be tested; said at least one conditional branch instruction having at least a first encoding predicting a first state of said condition and having at least a second encoding predicting a second state of condition.
References Cited (Backward Citations)
US4370711A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-03-06 | 1987-09-05 | 1988-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-06 | 1991-09-05 | 1992-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-06 | 1995-09-05 | 1996-03-06 | $7700.00 | Window Closed / Lapsed |