Method Of Storing Bit-Pattern In Plural Printer Cartridges

1 . A method of storing a bit-pattern in each of a plurality of printer cartridges of a printing system, each of the printer cartridges having a memory, the method comprising, for each printer cartridge:

(a) determining a first memory location which is different than a first memory location in at least a plurality of the other printer cartridges; and

(b) storing the bit-pattern at the determined first memory location;

wherein the different first memory locations are determined such that the bit-pattern storage location of all the respective printer cartridges cannot be ascertained from the bit-pattern storage location of any one of the printer cartridges.

2 . A method according to claim 1 , wherein step (a) includes randomly selecting the first memory location.

3 . A method according to claim 2 , wherein step (a) includes selecting the first memory location based on a stochastic process or mechanism.

4 . A method according to claim 1 , wherein step (a) includes selecting the first memory location from an existing list or sequence of memory locations.

5 . A method according to claim 1 , wherein each memory is incorporated in a quality assurance integrated circuit of each printer cartridge.

6 . A method according to claim 1 , wherein the memory is non-volatile memory.

7 . A method according to claim 6 , the method further comprising storing one or more code segments in the memory of each printer cartridge, the one or more code segments including data indicative of the first memory location at which the bit-pattern is stored on that printer cartridge.

8 . A method according to claim 1 , wherein the first memory locations of the printer cartridges are selected such that, from printer cartridge to printer cartridge, there is no overlap of the positions of at least some of the bits, bytes or characters of the devices' respective bit-pattern.

9 . A method according to claim 1 , wherein the first memory locations of the printer cartridges are selected such that, from printer cartridge to printer cartridge, positions of at least some of the bits, bytes or characters of the printer cartridges' respective bit-patterns overlap.

10 . A method according to claim 9 , wherein the first memory locations of the printer cartridges are selected such that, from printer cartridge to printer cartridge, bit, byte or character positions of the printer cartridges' respective bit-patterns are shuffled, rotated or otherwise ordered differently.

11 . A method according to claim 1 , wherein the first memory locations of the printer cartridges are selected such that, from printer cartridge to printer cartridge, bit, byte or character positions of the printer cartridges' respective bit-patterns are shuffled, rotated or otherwise ordered differently.

12 . A method according to claim 1 , comprising:

applying a function to the first bit pattern and a second bit pattern, thereby to generate a result; and

storing the result in the first memory location, thereby indirectly storing the first bit-pattern.

13 . A method according to claim 12 , wherein the function is a logical function.

14 . A method according to claim 13 , wherein the logical function is an XOR function.

15 . A method according to claim 12 , wherein the first bit-pattern is a key.

16 . A printer cartridge having a bit-pattern stored in it in accordance with the method of claim 1 .

17 . A printer cartridge having a bit-pattern and a result stored in it in accordance with the method of claim 12 .

18 . A plurality of printer cartridges having respective bit-patterns stored in them in accordance with the method of claim 1 .

19 . A plurality of printer cartridges having respective bit-patterns and results stored in them in accordance with the method of claim 12.