Controlling SDRAM memory by using truncated burst read-modify-write memory operations
First Claim
1. A method for truncating a read portion of a read-modify-write memory operation, the memory operation being performed on a plurality of memory lines, a first memory line of the plurality of memory lines having tag data which describes a current state of data stored in the remaining memory lines, the method comprising the steps of:
- issuing an activation command to initiate the memory operation;
issuing a read command;
reading the first memory line;
asserting a mask signal to block reading of the remaining memory lines;
updating the tag data which was read from the first memory line;
issuing a write command;
writing the remaining memory lines;
writing the first memory line with the updated tag data after the step of writing the remaining memory lines; and
issuing a precharge command to complete the memory operation.
3 Assignments
0 Petitions
Accused Products
Abstract
In a computer system having SDRAM memory banks that use a full burst read-modify-write operation as the sole mode for conducting memory operations, by selectively truncating the memory operation, it is possible to simulate either a burst read operation or a burst write operation. In a truncated read operation, a full read portion of the memory operation is performed. The tag is read with the first data line and is updated while the remaining lines of the burst are read. The tag is written using the write portion, but then the burst operation is aborted or truncated by issuing a precharge command to abort the write after the first line of the write is completed. This saves three clock periods out of a cycle of seventeen clock periods. A truncated write operation is similar to the read operation. A full burst read is started to retrieve the tag, which is stored to the first line, but the burst is truncated after the first line has been read. A full burst write operation is started immediately after the tag read, with the last lines of the data being written first. The tag data in the first line is being updated while the last three lines are being written. Then the cycle wraps around to write the first data line, including the tag, on the last cycle of the burst write.
61 Citations
31 Claims
-
1. A method for truncating a read portion of a read-modify-write memory operation, the memory operation being performed on a plurality of memory lines, a first memory line of the plurality of memory lines having tag data which describes a current state of data stored in the remaining memory lines, the method comprising the steps of:
-
issuing an activation command to initiate the memory operation; issuing a read command; reading the first memory line; asserting a mask signal to block reading of the remaining memory lines; updating the tag data which was read from the first memory line; issuing a write command; writing the remaining memory lines; writing the first memory line with the updated tag data after the step of writing the remaining memory lines; and issuing a precharge command to complete the memory operation.
-
-
2. A method for truncating a write portion of a read-modify-write memory operation, the memory operation is performed on a memory cache of a plurality of memory lines, a first memory line of the plurality of memory lines has tag data which describes a current state of data stored in the remaining memory lines, the method comprising the steps of:
-
issuing an activation command to initiate the memory operation; issuing a read command; reading the first memory line; reading the remaining memory lines; updating the tag data which was read from the first memory line; issuing a write command; writing the first memory line with the updated tag data after the step of reading the remaining memory lines; asserting a mask signal to block writing of a second memory line of the plurality of memory lines; and issuing a precharge command after the step of asserting a mask signal to truncate the memory operation and block the writing of the remaining lines.
-
-
3. A method for truncating a read portion of a read-modify-write memory operation, the memory operation being performed on a memory cache of a plurality of memory lines equal to the burst length of a particular memory, a first memory line of the plurality of memory lines having tag data which describes a current state of data stored in the remaining memory lines, the method comprising the steps of:
-
reading the first memory line; asserting a mask signal to block reading of the remaining memory lines; updating the tag data which was read from the first memory line; writing the remaining memory lines; and writing the first memory line with the updated tag data after the step of writing the remaining memory lines. - View Dependent Claims (4, 5, 6, 7)
-
-
8. A method for truncating a write portion of a read-modify-write memory operation, the memory operation is performed on a memory cache of a plurality of memory lines equal to the burst length of a particular memory, a first memory line of the plurality of memory lines has tag data which describes a current state of data stored in the remaining memory lines, the method comprising the steps of:
-
reading the first memory line; reading the remaining memory lines; updating the tag data which was read from the first memory line; writing the first memory line with the updated tag data after the step of reading the remaining memory lines; asserting a mask signal to block writing of a second memory line of the plurality of memory lines; and issuing a precharge command after the step of asserting a mask signal to truncate the memory operation and block the writing of the remaining lines. - View Dependent Claims (9, 10, 11, 12)
-
-
13. A computer system having SDRAM memory chips that use a full burst read-modify-write operation as a mode for conducting memory operations, the computer system comprises:
-
means for issuing commands to the memory banks; and means for selectively truncating the memory operation to simulate either a burst read operation or a burst write operation, as directed by the processor. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
-
-
24. A method for shortening the memory operation cycle in a processor system using SDRAM and using tag data to describe a current state of data stored in the SDRAM, the method comprising the steps of:
-
issuing a burst activate command to the SDRAM where the burst command is to effect several identified lines of the SDRAM within the burst cycle; updating the tag data; activating data within the burst cycle with respect to a certain number of the burst command identified lines of the SDRAM; and selectively inhibiting activation within the burst cycle with respect to a certain number of the burst command identified lines of the SDRAM. - View Dependent Claims (25, 26, 27, 28, 29)
-
-
30. A method for shortening the memory operation cycle in a SDRAM memory system in which blocks of data are stored in a block spanning several lines of the memory and where tag information is associated with each of such data blocks, the method comprising the steps of:
-
activating a read-modify-write burst cycle with respect to a selected data block, where the burst cycle would require t clock periods to execute the full cycle; and inhibiting selected memory line activations, where the number of lines that are inhibited is 1 so as to reduce the number of burst cycle clock periods to t-1. - View Dependent Claims (31)
-
Specification