Serially connected memory having subdivided data interface

1. A memory system comprising:

a controller; and

a plurality of memory devices serially interconnected with the controller via an n-bit data interface,

the memory system being configurable in a first mode to communicate each read and write operation between the controller and the memory devices using all n bits of the data interface;

the memory system being configurable in a second mode to concurrently:

communicate data associated with a first operation between the controller and a first target memory device using only m bits of the data interface, where m is less than n; and

communicate data associated with a second operation between the controller and a second target memory device using the remaining n-m bits of the data interface.

2. The memory system of claim 1 , wherein:

the first operation is a read operation; and

the second operation is a write operation.

3. The memory system of claim 2 , wherein the second target memory device is connected downstream of the first target memory device.

4. The memory system of claim 2 , wherein m and n-m are equal.

5. The memory system of claim 2 , wherein the controller is further configurable in the second mode to communicate commands associated with the first and second operations on only the remaining n-m bits of the data interface.

6. A memory device comprising:

n data input pins for receiving data from a first external device;

n data output pins for transmitting data to a second external device; and

internal logic selectively configurable to operate the memory device in one of a first mode and a second mode,

when operating in the first mode, the memory device being operative to:

receive data associated with a single operation on all n data input pins; and

transmit data associated with a single operation on all n data output pins; and

when operating in the second mode, the memory device being operative to concurrently:

receive data associated with a first operation on only m of the data input pins;

transmit data associated with the first operation on only m of the data output pins;

receive data associated with a second operation on the remaining n-m of the data input pins; and

transmit data associated with the second operation on the remaining n-m of the data output pins,

where m is less than n.

7. The memory device of claim 6 , wherein:

the first operation is a read operation; and

the second operation is a write operation.

8. The memory device of claim 7 , wherein:

a target device of the write operation is connected downstream of the data output pins; and

a target device of the read operation is connected upstream of the data input pins.

9. The memory device of claim 7 , wherein m and n-m are equal.

10. The memory device of claim 7 , wherein:

the internal logic is further configurable in the second mode to receive commands associated with the first and second operations on only the remaining n-m data input pins.

11. A memory controller, comprising:

an n-bit data interface for communicating with a plurality of serially-connected memory devices; and

internal logic configurable to operate in a first mode to communicate each read and write operation to the memory devices using all n bits of the data interface;

the memory controller being configurable in a second mode to concurrently:

communicate data associated with a first operation to the memory devices using only m bits of the data interface, where m is less than n; and

communicate data associated with a second operation to the memory devices using the remaining n-m bits of the data interface.

12. The memory controller of claim 11 , wherein:

the first operation is a read operation; and

the second operation is a write operation.

13. The memory controller of claim 12 , wherein a target memory device of the write operation is connected downstream of a target memory device of the read operation.

14. The memory controller of claim 12 , wherein m and n-m are equal.

15. The memory controller of claim 12 , being further configurable in the second mode to communicate commands associated with the first and second operations on only the remaining n-m bits of the data interface.

16. A method of operating a plurality of serially-connected memory devices connected by an n-bit data interface, the method comprising:

sending a first command from a memory controller, the first command being addressed to a first target memory device;

communicating data associated with the first command between the memory controller and the first target memory device on only m bits of the data interface;

sending a second command from the memory controller, the second command being addressed to a second target memory device; and

communicating data associated with the second command between the memory controller and the second target memory device on only the remaining n-m bits of the data interface.

17. The method of claim 16 , wherein communicating data associated with the first command and communicating data associated with the second command are performed concurrently.

18. The method of claim 17 , wherein communicating data associated with the first command and sending the second command are performed concurrently.

19. The method of claim 18 , wherein:

the first and second commands are sent using only the remaining n-m bits of the data interface.

20. The method of claim 16 , wherein:

one of the first and second commands is a read command, and the other of the first and second commands is a write command.

21. The method of claim 20 , wherein:

the target memory device of the write command is connected downstream of the target memory device of the read command.

22. The method of claim 20 , wherein m is equal to n-m.