Universal timing waveforms sets to improve random access read and write speed of memories
Methods of increasing the speed of random read and write operations of a memory device are provided for improving the performance of volatile and non-volatile memory devices. In contrast to the conventional approach that latches the current memory address right before the currently accessed memory data are outputted, the methods latch the next memory address before the currently accessed memory data are read out. The flow, timing waveforms and control sequences of applying the methods to parallel NOR flash, parallel pSRAM, serial SQI NOR flash and NAND flash are described in detail. The NOR flash device designed with the method can be integrated with a NAND flash device on a same die in a combo flash device packaged in either an ONFI compatible NAND flash package or other standard NAND flash package.
1. A method of executing a memory operation command for accessing memory data of a plurality of memory addresses of a memory device, comprising the orderly steps of:
(a) latching a first memory address of the plurality of memory addresses into stacked registers of the memory device;
(b) latching a second memory address of the plurality of memory addresses into the stacked registers;
(c) accessing the memory data of a current memory address in the stacked registers and removing the current memory address from the stacked registers, the current memory address being the memory address latched earliest in the stacked registers immediately before being removed;
(d) checking if a last memory address of the plurality of memory addresses has been latched or not;
(e) latching a next memory address of the plurality of memory addresses not latched yet into the stacked registers and returning to step (c) if the last memory address has not been latched; otherwise, proceeding to step (f); and
(f) accessing the memory data of the memory address still latched in the stack registers and removing the memory address from the stacked registers to complete the memory operation command.
2. The method according to claim 1 , wherein the memory operation command is an asynchronous mode read command for reading the memory data of a parallel NOR flash memory device.
3. The method according to claim 1 , wherein the memory operation command is an asynchronous mode read command for reading the memory data of a parallel pseudo SRAM device.
4. The method according to claim 1 , wherein the memory operation command is a synchronous mode read command for reading the memory data of a parallel NOR flash memory device.
5. The method according to claim 1 , wherein the memory operation command is a synchronous mode read command for reading the memory data of a parallel pseudo SRAM device.
6. The method according to claim 1 , wherein the memory operation command is an asynchronous mode read command for reading the memory data of a serial SQI NOR flash device.