Title of Invention

REGISTER FILE APPARATUS AND METHOD INCORPORATING READ-AFTER-WRITE BLOCKING USING DETECTION CELLS

Abstract A register file apparatus and method incorporating read-after-write blocking using detection cells provides improved read access times in high performance register files. One or more detection cells identical to the register file cells and located in the register file array are used to control the read operation in the register file by configuring the detection cells to either alternate value at each wriue or change to a particular value after a write and then detecting when the write has completed by detecting the state change of an active detection cell. The state change detection can be used to delay the leading edge of a read srrobe or may be used in the access control logic to delay generation of a next read strobe. The register file thus provides a scalable design that does not have to be tuned for each application and that tracks over voltage and clock skew variation.
Full Text REGISTER FZLE APPARATUS AND METHOD INCORPORATING READ-AFTER-WRITE
BLOCKING USING DETECTION CELLS
CROSS-REFERENCE TO RELATED APPLICATION
The present application is related to co-pending U.S. Patent Application "DYNAMIC-STATIC LOGICAL CONTROL ELEMENT FOR SIGNALING AN INTERVAL BETWEEN THE END OF A CONTROL SIGNAL AND A LOGICAL EVALUATION"f Serial No. 10/922,271, filed concurrently with this application by the same inventors and assigned to the same Assignee. The specification of the above-referenced application is incorporated herein by reference.
FIELD OF INVENTION
The present invention relates generally to register file access control circuits, and more particularly to a register file having automatic read-after-write blocking.
BACKGROUND
Register files are commonly used building blocks in digital circuits, particularly in processing system components where fast access to a fairly small quantity of data is required with low access latency. Examples of register file uses include register arrays in processors, cache directories in cache memories.
In contrast to static random access memory (SRAM) cells, register file cells are often written to and then read from within the same clock cycle. For processor core elements where register files are storing machine state information, register files are almost always read

within clock skew variation, voltage variation, and other factors that could cause the reading of false or unstable data.
Typical design margins for register file read-after-write timing may waste up tc 30% of the clock cycle time by waiting until the write cvcle is complete. But such margins are necessary within the typical ranges cf the operational variables mentioned above and with current circuits used to implement register file cells and control logic.
Therefore, it would be desirable to further reduce the read-after-write margins to improve register file performance and the performance cf processors using register files for storage of values and state information.
SUMMARY OF INVENTION
Aspects of the present invention include a register file apparatus and a method for operating a register file apparatus, which can achieve desired register file performance and processor performance. One or more cells within the register file are dedicated to use as a detection mechanism for determining when the end of a write cycle has occurred. One cell may be used for the entire array, one cell may be assigned for each row in the register file array, or cells may be assigned for groups of rows.
The detection cells may be connected so that the value of the cells alternates at each write operation and the value cf an active detection cell is used to control logic that blocks a read to the register file row until the active detection cell changes state. Alternatively, the detection cells may be configured so that a first state is set prior to the commencement of the write cycle and then the detection cells are written with a value corresponding to the opposite state by the write.
The indication of a detection cell state change can be used to truncate the leading edge of a next read strobe to the storage ceils

One aspect of the invention provides a method for reducing read-after-write delays in a register file circuit. The method comprises: writing one or more values to a register within said register file circuit; substantially simultaneously, with said writing, triggering a state change in at least one dedicated detection cell within said register file circuit; blocking read access to said register at commencement of said writing and until said blocking is canceled; detecting when said at least one detection cell has changed state as a result of said triggering; and canceling said blocking, whereby said register can be read.
Another aspect of the invention provides a register file array comprising: a plurality of storage cells for storing bit values and arranged as logical rows and columns; at least one detection cell configured to change state in response to a write to a row of said plurality of storage cells; and a clock steering logic preventing read access to said row until a state of an output of said at least one detection cell has changed by detecting a state change of said at least one detection cell.
Another aspect of the invention provides a register file array, comprising:
a plurality of storage cells for storing bit values and arranged as logical rows and columns;
at least one detection cell configured to change state in response to a write to a row of said plurality of storage cells, wherein said at least one detection cell is a scannable storage ceil comprising a scan latch and a detection storage ceil, wherein an inverted output of said scan latch is coupled to an input of said detection storage cell and an input of said scan latch is coupled to an output of said detection storage cell, and wherein a scan clock input of said scan latch is coupled to a write strobe of said register file array and responsive to a de-asserted state of said write strobe, whereby a state of said at least one detection cell is stored between writes; and
a clock steering logic preventing read access to said row until a

preventing is maintained until said detection output of said scan latch and said output of said detection storage cell are at different logical values.
The fcregoing and other features and advantages of the invention will be apparent from the following description of the preferred embodiment of the invention, as illustrated in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the invention is described below in more detail, by way of example, with reference to the accompanying drawings in which:
Figure 1 is a block diagram of a register file in accordance with an embodiment of the invention.
Figure 2A is a block diagram of a detection cell and associated control logic as may be used in the register file of Figure 1.
Figure 2B is a block diagram of another detection cell and associated control logic as may be used in the register file of Figure 1.
Figure 3 is a timing diagram depicting the relationship of signals within the register file of Figure 1.
Figure 4 is a block diagram depicting control logic within the register file of Figure 1, in accordance with an alternative embodiment of the present invention.
Figure 5 is a schematic depicting details of dynamic control logic as may be used in the circuit of Figure 2B.
Figure 6 is a schematic depicting details of dynamic control logic as may be used in the circuit of Figure 2A..
DESCRIPTION OF EMBODIMENT

embodying a method and an apparatus in accordance with the present invention.
An array of storage cells 12 provide storage for words in rows aligned across the figure. Each bit in the words forms a column running up and down the figure. The physical layout of storage cells 12 generally mimics the layout depicted, but may vary, for example the rows may be partitioned into two or more units, in which case the layout of a portion cf the row may mimic that portion of the drawing, but the overall layout of the register file may be split. Storage cells 12 are coupled to a control logic 10 that provides strobe signals that control the individual storage cells 12 in order to perform read and write functions to the registers (rows) within the register file. It should be understood that rows and columns may be interchanged in a particular register file design and that the term "rows" is used herein and in the claims to indicate the group of storage ceils corresponding to an individual storage "word", which may be of any bit-width. Control logic 10 also may be coupled to a scan logic 16 testing capability for the register file circuit via generating special functional/scan clock relations to storage cells 12 and detection cells 14. Data input and output buffers/latches 18 provide for input and output cf data from storage cells 12.
Unique to the register file disclosed in . Figure 1, is the addition of one or more detection cells 14 (and/or detection cells 14A and 142) . The detection cells are used to provide a signal that indicates when all of storage cells 12 implicated in a given write operation have assumed the state directed by the data written to storage cells 12. The detection is performed by using cells having characteristics matched to storage ceils 12 so that over operational variations such as clock skew, power supply voltage, temperature variations and process variations, the delay between a write strobe and the actual .change of data in storage ceils 12 will be matched by the delay to produce a state change in detection ceii(s) 14 (and/cr 14A and 14Z) .
The number and location of detection cells can vary in accordance

distant end with respect to the clock (strobe) distribution network. In other words, the end cell in a row is the last to receive a strobe transition. Use of detection cells 14 thereby provides a signal to each row that can indicate when a write to that row should have resulted in a complete state change of any storage cells located in that row. Alternatively, a column of detection cells may be positioned at another location away from the ends of the rows, which is particularly useful in tuning the delay of the detection cell state change to read blocking delay. Other multiple detection ceil arrangements are possible, such as providing a detection cell 14 for every other row.
Alternatively, a single detection cell 14A or 14Z may be employed to provide a signal indicating completion of a write. (Or for split arrays, a single cell might be used for each portion of the array) . Detection cell 142 indicates the location of a single cell that corresponds to the end of the last row in the array, wherein "last" is defined in a manner similar to the above for "end", indicating the cell at the distant end of the clock distribution for both columns and rows. Therefore, detection ceil 142 provides an indication that all other cells implicated by a write should have completed their state changes. To ensure that a state change has occurred, the control logic 10 provides some delay for providing a margin of confidence before enabling a read after a write has occurred. In addition, location of detection cells in other locations such as detection cell 14A require that a delay be added to the write completion signal that compensates for the fact that other cells are expected to have state changes occurring later than the state change in detection cell 14A.
In general, the present invention is directed toward a register file circuit that includes one or mere detection cells that provide a write complete indication so that reads occurring earlier than the end of the write strobe cycle can be blocked or not generated until there is confidence that the data in storage cells 12 is stable. Detection cells (14, 14Z) can either provide such indication directly, wherein control circuit 10 only includes such additional delay as needed for confidence margin. Or, detection cells such as detection cell 14A can provide an

write is known to be completed, which is typically accomplished in the prior art by delaying the read strobe until the write strobe is de-asserted. In some dynamic circuit designs, a fixed margin is added after the beginning of the write strobe and is used to enable the next read.
The result cf applying the techniques of the present invention is an increased performance in terms of throughput of a register file circuit. Further, the circuit achieves better delay scaling over operational parameters, permitting increased frequency of operation and a design in which the above-mentioned margin does not have to be evaluated extensively. A further result provides for asynchronous read operations so that a read strobe to the same row is not generated at all until the state changes due to the write cycle are complete.
Referring now to Figure 2A, an example of a detection cell 24A connected to an exemplary control logic 10A that may be used within the control logic 10 circuit of Figure 1. Detection cell 24A is a modified storage cell having two inputs coupled through transmission gates TGI and TG2 (or pass gates using one pass transistor) to a buffer 31 with storage on the input of buffer Bl. One transmission gate TGI input is connected to a logical high value and the other input (of TG2) is connected to a logical low value. When Write Row becomes active (logic high), storage cell 24A was previously in logical low state due to the connection of an active low enable input of transmission gate TG2 to the Write Row signal and only transitions to a logical high state after Write Row is asserted and the inherent ciock-to-state-cnange delay of detection cell 24A has elapsed. The logical high state cf detection cell 24A is set by activation cf transmission gate TGI upon assertion of Write Row signal.
The output cf detection cell 24A is provided to control logic 10A through an optional delay D2, which as mentioned above, may be tuned to compensate fcr the location of detection cell 24A and may also provide the desired margin cf confidence in conjunction with the path delay to control logic 10A and control logic 10A internal delays. Within control logic 10A, logical AND gate 27 qualifies the row read strobe signal Row Read Stb to

logic circuit having a combined static and dynamic function. A specific circuit having the static function incorporated within the dynamic AND gate will be illustrated in detail below in Figure 6 and the associated description. The summing node of a dynamic domino circuit represented by inverter II is connected to an input of a static logical NAND gate 29. The precharge input of inverter II is connected to the Write Row signal, so that prior to the commencement of a write to the row, the output of inverter II is in a logical high state. Therefore, when the Write Row signal is asserted, both inputs of logical 'NAND gate 29 assume a logical high value that disables the Row Read Stb signal via AND gate 27 until the inherent clock-to-state-change delay of detection cell 24A has elapsed plus any additional delay due to delay D2.
When the inherent clock-to-state-change delay of detection cell 24A has elapsed plus any additional delay due to delay D2, inverter II evaluates, providing a logical low value at the input of NAND gate 29. The output of NAND gate 29 will then assume a logical high state, enabling the Row Read Stb signal via AND gate 27. Inverter II will continue to provide a logical low value at the input of NAND gate 2 9 until the Write Row signal is de-asserted. When Write Row is deasserted, inverter II is precharged for the next evaluation, but the connection of the Write Row signal to NAND gate 2 9 ensures that the output of NAND gate 2 9 will continue to enable the Row Read Stb signal until the next write to the row begins, which prevents the Read Row cycle from being truncated by de-assertion of the Write Row signal.
While the illustration shows the gating function present in separate control logic 10A (as part of control logic 10 of Figure 1) it should be understood that the physical location of the gating function can be provided locally at each row cell or by one gate located in the row, with a distribution of the detection cells 14 outputs along the row lines.
Referring now to Figure 2B, another detection cell circuit and associated control logic 10B is shown that is particularly advantageous in register file circuits having scannable architecture. In the depicted

connected to the enable input of detection cell 24B (which is a standard storage ceil) and an inverted version provided to scan latch 22 via an inverter 12. An .inverted output of scan latch 22 is provided to the write data input of storage cell 24B, so that the logical value stored in detection cell 24B alternates at each write strobe. Since the value in scan latch 22 is not updated until after the Write Row signal is de-asserted, initially the values cf scan latch 22 and storage cell 24B will be the same and will continue to be the same until the Write Row signal is asserted and rhe inherent clock-ro-stare-change delay of detection cell 243 has elapsed.
Control logic 10B detects when rhe outputs of detection cell 24B and scan latch 22 are different, providing an indication as described above for the circuit of Figure 2A, optionally delayed by delay D2 that delays the detection ceil 24B output change and thereby provides a write complete (WriteConrp) signal via a dynamic XNOR gate and static NAND gate 29. A dynamic XNOR circuit having an incorporated static NAND function are shown in detail below in Figure 5 and the associated description.
The preset input of dynamic XNOR gate 25 is connected to the Write Row signal so that the output of XNOR gate 25 remains in the precharge state except after the Write Row signal has been asserted and before the optionally delayed output of detection cell 24B has changed state due to the write cycle. When the Write Row signal is asserted, both inputs of NAND gate 29 assume a logical high value, as the inputs of XNOR gate 25 are ecrual at this time, preventing XNOR gate 25 from evaluating. The output of NAND gate 2 9 will thus be at a logical low level, blocking any Row Read Stb assertion that has arrived before the state change due to the write cycle has occurred. When the inherent clock-to-state-change delay of detection cell 24B has elapsed plus any additional delay due ro delay D2, dynamic XNOR gate 25 evaluates, providing a logical low value at the input of NAND gate 29 that is connected to XNOR gate 29. The output of AND gate 2 9 will then assume a logical high state, enabling the Row Read Stb signal via AND gate 27. Dynamic XNOR gate 25 will continue to provide a logical low value at the input of NAND gate 29 until the Write Row signal is de-

the Read Row cycle from being truncated by de-assertion of the Write Row
signal when the output of scan latch 22 changes state.
Referring now to Figure 3 a timing diagram illustrating the
M
operation of the circuit of Figure 2B within the register file circuit of Figure 1 is depicted. For the circuir of Figure 2A operation for each cycle is similar to the firsu cycle (left hand side) shown in Figure 3r as ~he initial value of the detection cell in Figure 2A does not alternate between cycles. Upon and prior to receiving a WriteRow signal, the detection cell output (DetStorageCell) matches the scan latch output (DetScanLatch) and the WriteComp signal is low. When the inherent clock-to-state- change delay of defection cell 24B has elapsed, DetStorageCell assumes a value opposite that of DetScanlUatch (due TO rhe connection of scan latch 22 inverting output to detection cell 24B input) and XOR gate 25 transitions to a logical high value, providing the WriteComp signal that qualifies the row read strobe RowRead to provide the ReadRow signal that drives the row read strobes to storage ceils 12. Thus as can be seen from Figure 3 the ReadRow signal is truncated from the RowRead signal until the delay has expired. Also illustrated in the figure is uhe provision of a cell delay (I.e., the inherent detection cell write strobe to state change delay) added to a tuned delay, which includes the confidence margin and any delay needed to tune for a detection cell that is not guaranteed to be the last cell to transition on a write operation.
Referring now to Figure 4, an alternative blocking mechanism is depicted in the form of an alternative control logic IOC as may be ■ employed within the register file circuit of Figure 1. Control logic IOC receives the Write Comp signal (s) at an address unit 4 4 that compares a next, read address to the previous write address in order to determine whether or not read access to a row needs to be blocked until detection cell(s) 14 have detected that the state changes due to the previous write have occurred. If not, the generation of the Row Read Stb signal is postponed until the WriteComp indication is received. At that time, Strobe generators /line buffers 42 provides the appropriate read strobe.

the combination of dynamic XNOR 25 and NAND 29. A logical exclusive-NOR function is provided at an internal summing node NodeO by two N-device trees, transistors N60 and N61 forming the first tree and transistors N62 and N63 forming the second tree. The gates of transistors N61 and N63 are driven by scan latch 22 output and a complement provided by inverter 161, respectively. Similarly, transistors N60 and N62 are driven by detection cell 24B output and a complement provided by inverter 160. The resulting function is a dynamic exclusive-NQR at Node 0, with precharge transistor P60 and foot transistor N54 completing the dynamic circuit function. A half-latch HL60 provides that the state of internal node NodeO will be maintained in the absence of the precharge signal both before and after an evaluation has occurred. Inverter 162 transforms the internal node signal NodeO to provide what would be a traditional exclusive-OR function at output Write Compl, but for the presence of output foot transistor N65 and output pull-up transistor P61. When the /Precharge input (in this case the Write Row) signal is in a logic low state (during the absence of the write strobe), foct transistor N65 is turned off, disabling the action of the exclusive-OR by disabling inverter 162. Also, transistor P61 is turned on, causing the output of the circuit to be forced to a logic high value while the /Precharge input is active (thus transistor N65 is necessary in order to prevent shorting -the pulled-up output through inverter 162) . The operation of the above-described circuit is counterintuitive in that in typical dynamic logic gates, an output state change from the precharged state is reflective of an evaluated state of the internal summing node. However, in the illustrated circuit, the output state change is made upon de-assertion of the /Precharge signal and remains until the circuit has evaluated. Thus the illustrated circuit is especially suitable for the operation of the present invention, where it is desirable to generate a signal indicative of the time between the initiation cf the row write and the change at the control logic input (s) due to the expiration cf the inherent detection cell delay.
Referring now to Figure 6 a specific circuit that may be used to implement control logic 10A cf Figure 2A is shown. The illustrated circuit is a simplification of the circuit of Figure 5 and thus only differences will

precharge signal, only transistor N62 is needed for the evaluation tree and the internal summing node represents a dynamic-logic invert of the detection cell output (i.e., the summing node will be at a logical low value only if the circuit is not in the precharge condition and the . detection cell output is in a logical high condition). The balance of the circuit operates as described for the circuit of Figure 5, with a logical NAND function imposed on the state of the internal summing node where one of the NAND inputs is the /Precharge signal. When the /Precharge signal is de-asserted, the precharged state of "the internal summing node will cause the output of the illustrated circuit to transition to a logical low state (after being held up by transistor P61 during the precharge cycle). When the detection cell output transitions to a logical high state, the output of the illustrated circuit will return to a logical high state.
While the invention has been particularly shown and described with reference to the preferred embodiment thereof, it will be understood by those skilled in the art that the foregoing and other changes in form, and details may be made therein without departing from the spirit and scope cf the invent i on.


CLAIMS
1. A method for reducing read-after-write delays in a register file
circuit, comprising:
writing one cr more values to a register within said register file
simultaneously with said writing, triggering a state change in at lease one dedicated detection ceil within said register file circuit;
blocking read access to said register at commencement of said writing and until said blocking is canceled;
detecting when said at least one detection cell has changed state as a result of said triggering; and
canceling said blocking, whereby said register can be read.
2. The method cf Claim 1, wherein said triggering comprises writing a value corresponding to an opposite state of a current state cf said at least one detection cell to said at least one detection ceil.
3. The method of Claim 2, wherein said at least one detection cell is a scannabie register file cell, and wherein said method further comprises storing said current state in a scan latch of said scannabie register file cell prior to said writing and wherein said triggering comprises writing a complement of a scan latch current value to said at least one detection ceil in response to said writing.
4. The method cf any one of claims 1 to 3, wherein said wherein said triggering comprises writing a predetermined value to said at least one detection cell, and wherein said method further comprises resetting said at least one detection cell to an opposite value from said predetermined value to said at least one detection cell prior to said writing, whereby said state change occurs from said opposite value to said predetermined value in response to said writing.
5. The method cf any one of claims 1 to 4, wherein said at least one

(ii) at a time before another cell in said register changes value in response to said writing, and wherein said method further comprises delaying a result of said detecting for a predetermined time, and wherein cancelling is performed in response to an end of said delaying.
6. The method of any one cf claims 1 to 4, wherein said at least one
detection ceil comprises a plurality of detection cells, one for each
register in said register file circuit, wherein said method further
comprises selecting a particular detection cell associated with said
register in response to said writing, whereby said triggering triggers
said state change in only said particular detection cell.
7. A register file array, comorising:
a plurality of storage cells for storing bit values and arranged as logical rows and columns;
at least one detection cell configured to change state in response to a write to a row cf said plurality of storage ceils; and
a clock steering logic preventing read access to said row until a state of an output of said at least one detection cell has changed by detecting a state change of said at least one detection ceil.
8. The register file array of Claim 7, further comprising a storage
register having an inverting output coupled to an input of said at least
one detection cell and an input coupled to an output of said at leas" one
detection cell, and further comprising control logic for writing a value
cf said storage register to said at least one detection ceil in response
to said write, whereby at each write access to said row a stored value
within said at least one detection cell alternates state, and/or said at
least one detection cell is a scannabie storage cell, and said storage
register is a scan latch associated with said scannabie storage cell.
9. The register file array of Claim 7, further comprising control logic
for setting said at least one detection cell to a predetermined state
before said write commences, and wherein said at least one detection cell

10. The register file array of Claim 1, wherein said at least one detection cell is a quantity of detection cells equal to a number of said logical rows, wherein a write strobe connected to said at least one detection cell is the write enable input for an associated row, and wherein said clock steering logic prevents read access to said associated row until the associated detection cell has changed state.
11. The register file array cf Claim 10, wherein said logical row's and columns are arranged in physical rows and columns and
(i) wherein each of said detection cells is located at a predetermined one of said columns, whereby a time of said state change occurs in predetermined relation with completion cf said write tc said row OR
(ii) wherein each cf said detection cells is-located substantially in the center of said associated row, whereby a time of said state change approximates a median time of completion cf state changes of said storage ceils due to said write to said row.
12. The register file array cf Claim 11, further comprising a delay circuit for providing a predetermined delay and having an input coupled to said output cf said at least one detection cell and an output coupled to said clock steering logic, whereby said clock steering logic stops preventing read access only after said state change has occurred and said predetermined delay has expired.
13. The register file array of Claims 7 to 12, wherein said at least one detection cell is a single detection cell.
14. The register file array of Claims 7 to 12, further comprising a delay circuit for providing a predetermined delay and having an input coupled to said output of said at least one detection cell and an output coupled to said clock steering logic, whereby said clock steering logic stops preventing read access only after said state change has occurred and said predetermined delay has expired.

(i) located substantially in the center of said physical rows and columns, whereby a time of said state change approximates a median time of completion of any write to said register file and wherein said predetermined delay is sufficient for delaying said stopping cf said preventing such that said any write has completed state changes in any affected cells in said plurality cf storage cells; and/or
(ii) located at the ends cf said physical rows and columns, whereby a time cf said state change, whereby a time of said state change occurs after completion of state changes of said storage cells due to a write to any row.
16. The register file array of Claim 1, wherein said clock steering logic is incorporated with an access control logic of said register file array and blocks generation of a read strobe to said row until an indication that said state change has occurred is received from said detection cell.22. The register file array of Claim 21, wherein seid indication is provided to an address unit of said access control logic, wherein said address unit contains an address comparator for comparing an address of said row to an address of a next row associated with said read access and wherein said access control logic delays generation of said read strobe only if said address of said next row is equal to said address of said row.
17. The register file array of Claim 16, wherein said indication is provided to an address unit of said access control logic, wherein said address unit contains an address comparator for comparing an address of said row to an address cf a next row associated with said read access and wherein said access control logic delays generation cf said read strobe only if said address of said next row is equal to said address of said row.
13. A register file array, comprising:
a plurality of storage cells for storing bit values and arranged as logical rows and columns;

scan latch is coupled to an input of said detection storage cell and an input of said scan latch is coupled to an output of said detection storage cell, and wherein a scan clock input of said scan latch is coupled to a write strobe of said register file array and responsive to a de-asserted state of said write strobe, whereby a state of said at least one detection cell is stored between writes; and
a clock steering logic preventing read access to said row un~il a state cf an output cf said at least one detection cell has changed by detecting a stare change of said at least one detection cell, wherein said clock steering logic is coupled to a detection output cf said scan latch and said output of said detection storage cell, and wherein said preventing is maintained until said detection output of said scan latch and said output of said detection storage cell are at different logical values.
19. h method for reducing read-after-write delays in a register file circuit, comprising:
writing one or more values to a register within said register file circuit;
responsive to said writing, triggering a state change in at least one dedicated detection ceil within said register file circuit;
blocking read access to said register at commencement of said writing and until said blocking is canceled;
detecting when said at least one detection ceil has changed state as a result cf said triggering; and
canceling said blocking, whereby said register can be read.

Documents:

1149-CHENP-2007 CORRESPONDENCE OTHERS 14-03-2011.pdf

1149-CHENP-2007 EXAMINATION REPORT REPLY RECEIVED 02-12-2011.pdf

1149-CHENP-2007 AMENDED CLAIMS 02-12-2011.pdf

1149-CHENP-2007 ASSIGNMENT 02-12-2011.pdf

1149-CHENP-2007 FORM-13 02-12-2011.pdf

1149-CHENP-2007 FORM-3 02-12-2011.pdf

1149-CHENP-2007 OTHER PATENT DOCUMENT 02-12-2011.pdf

1149-CHENP-2007 OTHER PATENT DOCUMENT 1 02-12-2011.pdf

1149-CHENP-2007 AMENDED CLAIMS 23-02-2012.pdf

1149-CHENP-2007 CORRESPONDENCE OTHERS 23-02-2012.pdf

1149-chenp-2007-abstract.pdf

1149-chenp-2007-claims.pdf

1149-chenp-2007-correspondnece-others.pdf

1149-chenp-2007-description(complete).pdf

1149-chenp-2007-drawings.pdf

1149-chenp-2007-form 1.pdf

1149-chenp-2007-form 26.pdf

1149-chenp-2007-form 3.pdf

1149-chenp-2007-form 5.pdf

1149-chenp-2007-pct.pdf


Patent Number 252528
Indian Patent Application Number 1149/CHENP/2007
PG Journal Number 21/2012
Publication Date 25-May-2012
Grant Date 21-May-2012
Date of Filing 19-Mar-2007
Name of Patentee INTERNATIONAL BUSINESS MACHINES CORPORATION
Applicant Address ARMONK, NEW YORK 10504
Inventors:
# Inventor's Name Inventor's Address
1 CHU, SAM, GAT-SHANG 7121 AVIGNON DRIVE ROUND ROCK TX 78681
2 KLIM, PETER, JUERGEN 2305 CYPRESS POINT EAST AUSTIN TX 78746
3 LEE, MICHAEL, JU, HYEOK 3416 BRATTON RIDGE CROSSING AUSTIN TX 78727
4 PAREDES, JOSE, ANGEL 3201 DUVAL ROAD APT 125 AUSTIN TX 78759
PCT International Classification Number G11C 7/22
PCT International Application Number PCT/EP05/54103
PCT International Filing date 2005-08-19
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10/922,247 2004-08-19 U.S.A.