Symmetric bit coding for printed memory devices

Information

  • Patent Grant
  • 10114984
  • Patent Number
    10,114,984
  • Date Filed
    Friday, September 2, 2016
    8 years ago
  • Date Issued
    Tuesday, October 30, 2018
    6 years ago
Abstract
A printed memory reader adapted to determine an original value from a printed memory device including a plurality of contact pads and an encoded value created by encoding the original value. The encoded value including N bits of data, where N is equal to a number of bits of data stored in the printed memory device. The printed memory reader includes a plurality of probes arranged to contact the plurality of contact pads and a memory storage element including instructions programmed to execute the steps: a) reading the encoded value or an inverse encoded value from the printed memory device using the plurality of probes to obtain a read value; and, b) decoding the read value to obtain a decoded value equal to the original value. The printed memory reader further includes a processor arranged to execute the instructions.
Description
TECHNICAL FIELD

The presently disclosed embodiments are directed to providing bit coding, more particularly to encoding and decoding N-bit memory devices, and even more particularly to encoding and decoding N-bit memory devices such that orientation of a memory device relative to a reader does not alter the determination of memory device contents.


BACKGROUND

Printed memory (PM) labels and devices are manufactured in a variety of sizes, including twenty (20) bit, which has a symmetrical arrangement of electrical contacts or contact pads. An example of a 20-bit PM is depicted in FIG. 1. In some instances, the orientation of label or device 20 and thereby pads 22 relative to reader 24 may be upside down, either due to symmetry of the carrier body or for compatibility among multiple configurations (See, e.g., FIG. 3 versus FIG. 4). With the standard configuration of PM label 20, reader 24 can read and write an upside-down label, with the effect of reversing the order of the bits.


The present disclosure addresses a method for encoding and decoding N-bit data so that label to reader orientation does not alter the determined value of a printed memory label.


SUMMARY

For an N-bit label, there are 2N possible states, including mostly non-palindromes and a few palindromes. This leaves O(2(N−1)) distinct states. The present disclosure provides an encoding mapping ƒ from “data” states to “encoded” states, and a decoding mapping g from “encoded” states to “data” states, where g recovers the original data even if the encoded state is reversed before decoding. In an embodiment, the present method analyzes a sequence of symmetrically oriented pairs in the encoded state. For each pair, if the bit values are identical, their shared value is retained and that embodiment of the present algorithm moves to the next pair. If the bit values in a pair are not identical, they are used to establish a reading direction and the remaining bits are collected as a group. Each pairwise comparison is a dictionary split, catching half as many cases as the previous comparison, until the only remaining values are palindromes.


In another embodiment, distinct encoded states are enumerated to establish a mapping. Specifically, those encoded states which are not less than their reverse are listed in a particular order based on triangular numbers. To encode a data state for a label with an even number of bits, the largest triangular number less than or equal to the data state is computed. The index of the triangular number is used for the first half of the encoded state, and the second half of the encoded state is given by the reverse of the remainder when the triangular number is subtracted from the data state. For a label with an odd number of bits, the least significant bit is placed in the center of the encoded state, and the rest of the encoded state is computed based on the even number of remaining bits. To decode an encoded state from a label with an even number of bits, the larger of the encoded state or its reverse is used. The triangular number indexed by the first half of the resulting state is computed. To this is added the reverse of the second half. For a label with an odd number of bits, the center bit is appended to the sum calculated from the even number of remaining bits.


The present disclosure sets forth an embodiment of this type, using a formulation that works for both odd and even values of N, as well as being directly extendible to cover the entire set of solutions to the problem statement via transformations including permutation transformations, symmetric bit-swapping transformations and symmetric bit-flipping transformations. Selection from among this family may be useful for mild encryption, i.e., to make the coding specific to a particular application, device, or user.


Broadly, the present disclosure sets forth a printed memory reader adapted to determine an original value from a printed memory device including a plurality of contact pads and an encoded value created by encoding the original value. The encoded value includes N bits of data, where N is equal to a number of bits of data stored in the printed memory device. The printed memory reader includes a plurality of probes arranged to contact the plurality of contact pads and a memory storage element including instructions programmed to execute the steps: a) reading the encoded value or an inverse encoded value from the printed memory label using the plurality of probes to obtain a read value; and, b) decoding the read value to obtain a decoded value equal to the original value. The printed memory reader further includes a processor arranged to execute the instructions.


Additionally, the present disclosure sets forth a printed memory reader adapted to determine a first value from a printed memory device including a plurality of contact pads and a second value created by encoding the first value. The second value including N bits of data, where N is equal to a number of bits of data stored in the printed memory device. The printed memory reader includes a plurality of probes arranged to contact the plurality of contact pads and a memory storage element comprising instructions programmed to execute the steps: a) reading a third value from the printed memory label using the plurality of probes, wherein the third value is equal to the second value or an inverse of the second value; and, b) decoding the third value to obtain a fourth value equal to the first value. The printed memory reader further includes a processor arranged to execute the instructions.


Moreover, the present disclosure sets forth a method of using a printed memory device for storage and retrieval of an original value. The method includes: a) encoding the original value to form an encoded value having N bits of data, where N is equal to a number of bits of data stored in the printed memory device, such that an alternate value cannot yield an alternate encoded value equal to the encoded value or an inverse encoded value; and, b) storing the encoded value on the printed memory device. In some embodiments, the method further includes: c) reading the encoded value using a printed memory reader to obtain a read value, wherein the read value is the encoded value or the inverse encoded value; and, d) decoding the read value to obtain the original value.


Other objects, features and advantages of one or more embodiments will be readily appreciable from the following detailed description and from the accompanying drawings and claims.





BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are disclosed, by way of example only, with reference to the accompanying drawings in which corresponding reference symbols indicate corresponding parts, in which:



FIG. 1 is a top plan view of an embodiment of a 20-bit printed memory device;



FIG. 2 is a top plan view of an embodiment of a 20-bit printed memory device having connections arranged in an asymmetric pattern to indicate orientation;



FIG. 3 is a top plan view of an embodiment of a printed memory device entering a reader in a first orientation; and,



FIG. 4 is a top plan view of an embodiment of a printed memory device entering a reader in a second orientation one hundred eighty (180) degrees rotated relative to the first orientation;



FIG. 5 is a cross-sectional schematic view of an embodiment of a printed memory device reader;



FIG. 6 is a flowchart depicting an embodiment of an algorithm for returning the 0-indexed jth least significant bit;



FIG. 7 is a flowchart depicting an embodiment of an algorithm for reversing a string;



FIG. 8 is a flowchart depicting an embodiment of an algorithm for converting numeric data to a string of “1”s and “0”s;



FIG. 9 is a flowchart depicting an embodiment of an algorithm for converting a string of “1”s and “0”s to numeric data;



FIG. 10 is a first portion of a flowchart depicting an embodiment of an algorithm for encoding data from N-bit memory, e.g., N-bit printed memory;



FIG. 11 is a second portion of a flowchart depicting the embodiment of the algorithm for encoding data from N-bit memory, e.g., N-bit printed memory, shown in FIG. 9;



FIG. 12 is a first portion of a flowchart depicting an embodiment of an algorithm for decoding data for N-bit memory, e.g., N-bit printed memory;



FIG. 13 is a second portion of a flowchart depicting the embodiment of the algorithm for decoding data for N-bit memory, e.g., N-bit printed memory, shown in FIG. 11;



FIG. 14 is a flowchart depicting an embodiment of an algorithm for encoding data from N-bit memory, e.g., N-bit printed memory; and,



FIG. 15 is a flowchart depicting an embodiment of an algorithm for decoding data for N-bit memory, e.g., N-bit printed memory.





DETAILED DESCRIPTION

At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the embodiments set forth herein. Furthermore, it is understood that these embodiments are not limited to the particular methodologies, materials and modifications described and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the disclosed embodiments, which are limited only by the appended claims.


Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which these embodiments belong.


As used herein, the term “inverse”, when in conjunction with a string or binary value, e.g., the inverse of a read value or the inverse read value, is intended to mean the reverse order of a particular value. For example, if a read value is “01001101”, an inverse of the read value or the inverse read value is “10110010”. Moreover, as used herein, the term “palindrome” is intended to mean a number or sequence of characters which reads the same backwards as forwards. For example, read values of “10011011001” and “1100110011” are both palindrome values. Furthermore, as used herein, the term ‘average’ shall be construed broadly to include any calculation in which a result datum or decision is obtained based on a plurality of input data, which can include but is not limited to, weighted averages, yes or no decisions based on rolling inputs, etc.


Additionally, as used herein, a “truncated value” is intended to mean a string or binary value having its terminal bit removed. For example, the truncated value for the binary value “10110010” is “1011001”. Furthermore, as used herein, a “diminished value” is intended to mean a string or binary value having its center bit removed. For example, the diminished value for the binary value “1011001” is “101001”.


Moreover, although any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of these embodiments, some embodiments of methods, devices, and materials are now described.


The various embodiments of the basic algorithm described herein has been implemented as Excel® functions in Visual Basic for Applications (VBA), together with a small set of more general functions for handling binary numbers. The current implementations handle numbers up to 49 bits, since this is the precision that can be stored in a single numeric Excel® cell. However, it should be appreciated that the present algorithms may include support for larger numbers of bits by storing the data in strings, and/or using a more sophisticated programming language to speed up encoding and decoding operations, e.g., C++ programming language.


The present algorithms provide a method by which a single reader module, e.g., reader 24, may be used for multiple configurations of printed memory device, e.g., wallet cards 26 and 28. The PM will be written with the wallet card integrated into a display card, as shown in cards 26 and 28 in FIGS. 3 and 4. The PM may then be read in this configuration, or the wallet card may be punched out along a semi-perf before reading the PM. By using reversed orientations, the two card configurations may each be registered appropriately to align the PM label with contacts within reader 24.


It should be appreciated that the embodiments described herein may be implemented with a printed memory reader. Reader 24 may include a plurality of probes 30 arranged to contact a plurality of contact pads 22. Reader 24 may further include memory storage element 32 including instructions programmed to execute the steps of the various embodiments set forth herebelow. Printed memory reader 24 further comprises processor 34 arranged to execute the aforementioned instructions.


Notation


[A . . . B) will represent the set {x∈Z:A≤x<B} where Z is the set of integers. Specifically, [0 . . . N) will represent the set of cardinality N representing the non-negative integers strictly less than N. If B≤A, then [A . . . B) is the empty set. The modulus function is defined such that 0≤x(mod b)<b and x=k·b+x(mod b) for some k∈Z. The floor function is defined by └x┘custom characterx−x(mod 1). The ceiling function is similarly defined by ┌x┐custom character−└−x┘. A mapping ƒ from set U to set V will be declared as ƒ:U→V. A composition of mappings ƒ:U→V and g:T→U will be denoted ƒ*g:T→V. The inverse off, if it exists, will of course be written as ƒ−1 with the identity mapping I, so that ƒ−1*ƒ=ƒ*ƒ−1=I. A binary number with N digits will be represented by x(N). The concatenation of two binary numbers is defined according to x(N)∘y(M)custom character(x·2M+y)(N+M). The specific mapping r is defined as the bit-reversal mapping, which may be defined recursively by (rx)(1)custom characterx(1) and r(x(N)∘y(M))=ry(M)∘rx(N). The triangular numbers tq are given by







t
q

=



q


(

q
+
1

)


2

.





Problem Statement


For an N-bit label, the possible states are └0 . . . 2N). Of these 2N states,






2



N
2








are palindromes, i.e., they are invariant under bit-reversal. That leaves







2
N

-

2



N
2









non-palindrome states. Each of these is indistinguishable from one other non-palindrome state with the same bits in reversed order. That means there are







2

N
-
1


-

2

(




N
2



-
1

)







distinct non-palindrome states when the orientation of the label is not known. The total number of distinct states under this condition is then








2

N
-
1


-

2

(




N
2



-
1

)


+

2



N
2





=



2

N
-
1


+

2

(




N
2



-
1

)



=


2

(




N
2



-
1

)


·


(


2



N
2




+
1

)

.








This means that we seek an encoding mapping







f



:





[


0












2

N
-
1



+

2

(




N
2



-
1

)



)




[

0












2
N


)






and a decoding mapping g:







[

0












2
N


)



[


0












2

N
-
1



+

2

(




N
2



-
1

)



)






such that g*ƒ=g*r*ƒ=I. In practice, there are a large number of choices of ƒ and






g
-



(


2

(

N
-
1

)


+

2

(




N
2



-
1

)



)

!

·

2

(


2

(

N
-
1

)


-

2

(




N
2



-
1

)



)








to be exact, although we will consider functions ƒ1 and ƒ2 to be equivalent when








x



[


0












2

N
-
1



+

2

(




N
2



-
1

)



)




(



f
1


x

=




f
2


x




f
1


x


=


rf
2


x



)

.








This reduces the space of mapping functions to







(


2

N
-
1


+

2

(




N
2



-
1

)



)

!





choices of ƒ and allows us to consider g to be the inverse of ƒ We will describe two embodiments in particular which are readily characterized in terms of N, then extend them to more general embodiments.


Embodiment A


The embodiment presented herebelow builds on one of the alternative strategies presented infra, i.e., Strategy 2. First, Strategy 2 is examined with the notation set forth above:

















Number of


Number of


Data
data states
Encoded
Reversed
code states







x(N−2)
2(N−2)
0(1) ° x(N−2) ° 1(1)
1(1) ° rx(N−2) ° 0(1)
2(N−1)










Clearly, half of the 2N available code states are not being used, so Strategy 2 is inefficient. Specifically, the 0(1)∘x(N−2)∘0(1) and 1(1)∘x(N−2)∘1(1)) code states do not code for any data state under this scheme. As a result, only 2(N−2) of the theoretical







2

N
-
1


+

2

(




N
2



-
1

)







distinguishable data states can be encoded, i.e., a waste of slightly more than one bit.


Embodiment A is similar to Strategy 2, but partitions the available data and code spaces to use all the available code states. To introduce Embodiment A, the solution will be presented first for even N and then for odd N. For N even:

















Number of


Number of


Data
data states
Encoded
Reversed
code states







(01)(2) ° y(N−2)
2(N−2)
0(1) ° y(N-2) ° 1(1)
1(1) ° ry(N−2) ° 0(1)
2(N−1)


(001)(3) ° x(1)
2(N−3)
x(1) ° 0(1) ° y(N−4)
x(1) ° 1(1) ° ry(N−4)
2(N−2)


° y(N−4)

° 1(1) ° rx(1)
° 0(1) ° rx(1)


.
.
.
.
.


.
.
.
.
.


.
.
.
.
.


(0 . . . 01)(N/2)
2(N/2)
x(N/2−2) ° 0(1)
x(N/2−2) ° 1(1) ° ry(2)
2(N/2+1)


° x(N/2−2)

° y(2) ° 1(1)
° 0(1) ° rx(N/2−2)


° y(2)

° rx(N/2−2)


(10 . . . 0)(N/2+1)
2(N/2−1)
x(N/2−1) ° 0(1)
x(N/2−1) ° 1(1) ° 0(1)
2(N/2)


° x(N/2−1)

° 1(1) ° rx(N/2−1)
° rx(N/2−1)


(0 . . . 0)(N/2)
2(N/2)
x(N/2) ° rx(N/2)
x(N/2) ° rx(N/2)
2(N/2)


° x(N/2)









For N Odd:

















Number of


Number of


Data
data states
Encoded
Reversed
code states







(01)(2)
2(N−2)
0(1) ° y(N−2)
1(1) ° ry(N−2)
2(N−1)


° y(N−2)

° 1(1)
° 0(1)


(001)(3)
2(N−3)
x(1) ° 0(1)
x(1) ° 1(1)
2(N−2)


° x(1)

° y(N−4)
° ry(N−4)


° y(N−4)

° 1(1) ° rx(1)
° 0(1) ° rx(1)


.
.
.
.
.


.
.
.
.
.


.
.
.
.
.


(0 . . . 01)(└N/2┘)
2┌N/2┐
x(└N/2┘−2)
x(└N/2┘−2)
2(┌N/2┐+1)


° x(└N/2┘−2)

° 0(1)
° 1(1) ° ry(3)


° y(3)

° y(3) ° 1(1)
° 0(1)




° rx(└N/2┘−2)
° rx(└N/2┘−2)


(10 . . . 0)(┌N/2┐)
2┌N/2┐
x(└N/2┘−1) ° 0(1)
x(└N/2┘−1)
2┌N/2┐


° x(└N/2┘−1)

° y(1)
° 1(1)


° y(1)

° 1(1)
° ry(1) ° 0(1)




° rx(└N/2┘−1)
° rx(└N/2┘−1)


(0 . . . 0)(└N/2┘)
2┌N/2┐
x(└N/2┘)
x(└N/2┘)
2┌N/2┐


° x(└N/2┘)

° y(1)
° ry(1)


° y(1)

° rx(└N/2┘)
° rx(└N/2┘)









For General N∈N and j∈[0 . . . └N/2┘):

















Number of


Number of


Data
data states
Encoded
Reversed
code states







(10 . . . 0)(┌N/2┐)
2└N/2┘
x(└N/2┘−1) ° 0(1)
x(└N/2┘−1) ° 1(1)
2┌N/2┐


° x(└N/2┘−1)

° y(1) ° 1(1)
° ry(1) ° 0(1)


° y(1)

° rx(└N/2┘−1)
° rx(└N/2┘−1)


(0 . . . 0)(└N/2┘)
2┌N/2┐
x(└N/2┘) ° y(1)
x(└N/2┘) ° ry(1)
2┌N/2┐


° x(└N/2┘) ° y(1)

° rx(└N/2┘)
° rx(└N/2┘)


(0 . . . 0)(j+2)
2(N−1)
x(j) ° 0(1)
x(j) ° 1(1)
2N


° x(j) ° y(N−2j−2)
2└N/2┘
° y(N−2j−2)
° ry(N−2j−2)
2┌N/2┐



2(┌N/2┐−1)
° 1(1) ° rx(j)
° 1(1) ° rx(j)
2(└N/2┘+1)










Using this general form, it is straightforward to describe an encoding mapping ƒ and decoding mapping g in an algorithm. Proof of the desired quality g*ƒ=g*r*ƒ=I is readily apparent to one having ordinary skill in the art upon inspection.


Example 1—Embodiment A—Encode—Between 25 and 29















Data payload is constructed
0001101011


Count leading zeros (3)
0001101011


For 3 leading zero, place 0 and 1 in the 3rd

——0————1——



position from the end


Drop leading zeros and the first 1 from the data
0001101011


payload


Note the next 3 − 1 = 2 digits
0001101011


Place the digits at the beginning and their
100————101


reverse at the end


Place the remaining digits in the middle
1001011101


Return encoded value
1001011101









Example 1—Embodiment A—Decode—Mismatch Before the Middle
















Original order
Reversed


















Read encoded value
1001011101
1011101001


Compare first and last digits
1001011101
1011101001


Continue inward until a
1001011101
1011101001


mismatch is found


If the mismatch reads . . . 1 . . .
1001011101
1001011101


0 . . . , reverse the number


Note the digits between the
1001011101
1001011101


mismatch


Place the digits between the

——————1011


——————1011



mismatch at the end


Note the digits before the 0
1001011101
1001011101


Place these digits before the

————101011


——————101011



filled digits


Place a 1 before the filled digits

———1101011


————1101011



Fill in with zeros
0001101011
0001101011


Return decoded value
0001101011
0001101011









Example 2—Embodiment A—Encode—Less than 25


















Data payload is constructed
0000010111



Count leading zeros (5)
0000010111



For 5 leading zeros, note the remaining digits
0000010111



Place the remaining digits at the beginning
10111—————



Place the same digits in reverse order
1011111101



Return encoded value
1011111101










Example 2—Embodiment A—Decode—No Mismatch (Palindrome)
















Original order
Reversed


















Read encoded value
1011111101
1011111101


Compare first and last digits
1011111101
1011111101


Continue inward until no
1011111101
1011111101


match is found


Note the first half of the
1011111101
1011111101


number


Place these digits at the end
_ _ _ _ _ 10111
_ _ _ _ _ 10111


Fill in with zeros
0000010111
0000010111


Return decoded value
0000010111
0000010111









Example 3—Embodiment A—Encode—More than 29















Data payload is constructed
1000000011


Count leading zeros (0)
1000000011


For 0 leading zeros, place 0 and 1 in positions
_ _ _ _ 01 _ _ _


flanking the middle


Note the last 4 digits and drop the rest
1000000011


Place the digits at the beginning and their
0011011100


reverse at the end


Return encoded value
0011011100









Example 3—Embodiment A—Decode—Mismatch in the Middle
















Original order
Reversed


















Read encoded value
0011011100
0011101100


Compare first and last
0011011100
0011011100


digits


Continue inward until a
0011011100
0011101100


mismatch is found


If the mismatch reads
0011011100
0011011100


. . . 1 . . . 0 . . . ,


reverse the number


Note the digits before the
0011011100
0011011100


mismatch


Place the digits before
_ _ _ _ _ _ 0011
_ _ _ _ _ _ 0011


the mismatch at the end


Place a 1 at the
1 _ _ _ _ _ 0011
1 _ _ _ _ _ 0011


beginning


Fill in with zeros
1000000011
1000000011


Return decoded value
1000000011
1000000011









Generalizations of Embodiment A


This embodiment suggests a number of other solutions that may be obtained via simple transformations relative to the proposed solution, including any combination of the following:

    • Any symmetric reordering of the encoded state, i.e., any composition of the invertible mappings sj, where j∈[0 . . . └N/2┘) and sj(x(j)∘y(N−2j)∘z(j))custom characterxj∘ry(N−2j)∘z(j)
    • Any symmetric bit-flipping operation, i.e., bitwise XOR between the encoded state and any N-bit palindrome
    • Swapping the interpretation of data states beginning with (0 . . . 01)(└N/2┘) and (0 . . . 00)(└N/2┘), i.e., to make the former map to palindromes and the latter to non-palindromes, rather than vice versa
    • Replacing y with ry and/or x with rx in some subset of the rows of the general solution table, including any subset of values of j.


      It is believed that such transformations may be useful for mild encryption, i.e., to make the coding specific to a particular application, device, or user. The above transformations generate 2(2N) related mappings. Trivially, the encoded state may be reversed for some subset of the possible data states or at random, but given the context these should not be considered to produce distinct mappings.


Implementation of Embodiment A


As described above, the foregoing basic algorithm has been implemented as a pair of Excel® functions in VBA, together with a small set of more general functions for handling binary numbers.













Format
Function







=BitSymEncA(Data, N)
Apply f to encode data


=BitSymDecA(Reading, N)
Apply g to decode data


=BitString(Data, N)
Convert numeric data to a string of “1”s and



“0”s


=BitValue(Data)
Convert a string of “1”s and “0”s to numeric



data


=StrRev(Reading, N)
Apply r to reverse a string of “1”s and “0”s


=LSB(Reading, j)
Return the 0-indexed jth-least-significant bit









Embodiment B


Embodiment B hinges on an explicit enumeration of all N-bit encoded states x(N) with the property x(N)≥rx(N). With







h



:





[

0













2

(




N
2



-
1

)


·

(


2



N
2




+
1

)



)




[

0












2



N
2





)






defined by







hp
=





-
1

+


1
+

8

p




2




,





note that








t
hp


p
<

t

hp
+
1



=


t
hp

+
hp
+
1






and






hp
<

2



N
2








2

(




N
2



-
1

)


·


(


2



N
2




+
1

)

.





















Number of


Number of


Data
data states
Encoded
Reversed
code states







p(2└N/2┘)
2(┌N/2┐−1) ·
hp(└N/2┘)
(p − thp)(└N/2┘)
2N


y(┌N/2┐−└N/2┘)
(2└N/2┘+ 1)
y(┌N/2┐−└N/2┘)
y(┌N/2┐−└N/2┘)




r(p − thp)(└N/2┘)
rhp(└N/2┘)









With this formulation, it is noted that the encoded value is never smaller than its inverse, and palindromes occur precisely when p is one less than a triangular number, i.e., p=thp+hp. The strategy behind Embodiment B becomes clearer when grouped by values of hp, as tabulated on the following tables. Here k is used for hp+1.


Solution Embodiment B

















Number of


Number of


Data
data states
Encoded
Reversed
code states







(0 . . . 0)(2└N/2┘)
2(┌N/2┐−└N/2┘) · 1
(0 . . . 0)(└N/2┘)
(0 . . . 0)(└N/2┘)
2(┌N/2┐−└N/2┘) · 1


y(┌N/2┐−└N/2┘)

y(┌N/2┐−└N/2┘)
y(┌N/2┐−└N/2┘)




(0 . . . 0)(└N/2┘)
(0 . . . 0)(└N/2┘)


[1 . . . 3)(2└N/2┘)
2(┌N/2┐−└N/2┘) · 2
(0 . . . 01)(└N/2┘)
[0 . . . 2)(└N/2┘)
2(┌N/2┐−└N/2┘) · 2


y(┌N/2┐−└N/2┘)

y(┌N/2┐−└N/2┘)
y(┌N/2┐−└N/2┘)




r[0 . . . 2)(└N/2┘)
(10 . . . 0)(└N/2┘)


.
.
.
.
.


.
.
.
.
.


.
.
.
.
.


[tk−1 . . . tk)(2└N/2┘)
2(┌N/2┐−└N/2┘) · k
(k − 1)(└N/2┘)
[0 . . . k)(└N/2┘)
2(┌N/2┐−└N/2┘) · k


y(┌N/2┐−└N/2┘)

y(┌N/2┐−└N/2┘)
y(┌N/2┐−└N/2┘)




r[0 . . . k)(└N/2┘)
r(k − 1)(└N/2┘)


.
.
.
.
.


.
.
.
.
.


.
.
.
.
.


[t2└N/2┘−1 . . . t2└N/2┘)(2└N/2┘)
2(┌N/2┐
(1 . . . 1)(└N/2┘)
[0 . . . 2)└N/2┘)(└N/2┘)
2(┌N/2┐


y(┌N/2┐−└N/2┘)

y(┌N/2┐−└N/2┘)
y(┌N/2┐−└N/2┘)




r[0 . . . 2)(└N/2┘)(└N/2┘)
(1 . . . 1)(└N/2┘)









Example 1—Embodiment B—Encode—Even N


















Data payload is constructed
0110101111



Use entire value for p
p = 431







Calculate hp




hp
=







-
1

+


1
+

8
·
431




2





=
28












Calculate p − thp





p
-

t
hp


=


431
-


28
*
29

2


=
25












Express hp in binary and place

11100 _ _ _ _ _




at the beginning




Express p − thp in binary and fill
1110010011



in in reverse




Return encoded value
1110010011










Example 1—Embodiment B—Decode—Even N
















Original order
Reversed


















Read encoded value
1110010011
1100100111


Compare to reverse
1100100111
1110010011


Select the larger
s = 1110010011
s = 1110010011


Note the first 5 digits
1110010011
1110010011


Use these digits as hp
hp = 28
hp = 28


Note the last 5 digits
1110010011
1110010011


Reverse these digits and evaluate
25
25


Calculate thp
t28 = 406
t28 = 406


Add these two values
25 + 406 = 431
25 + 406 = 431


Return decoded value
0110101111
0110101111









Example 2—Embodiment B—Encode—Odd N















Data payload is constructed
000101110


Use LSB for y
000101110 → y = 0


Use remaining bits for p

00010111
0 → p = 23






Calculate hp




hp
=







-
1

+


1
+

8
·
23




2





=
6










Calculate p − thp





p
-

t
hp


=


23
-


6
*
7

2


=
2










Express hp in binary and place

0110 _ _ _ _ _



at the beginning



Place y in the middle
01100 _ _ _ _


Express p − thp in binary and
011000100


fill in in reverse



Return encoded value
011000100









Example 2—Embodiment B—Decode—Odd N
















Original order
Reversed


















Read encoded value
011000100
001000110


Compare to reverse
001000110
011000100


Select the larger
s = 011000100
s = 011000100


Note the first 4 digits
011000100
011000100


Use these digits as hp
hp = 6
hp = 6


Note the middle digit
011000100
011000100


Use this digit as y
y = 0
y = 0


Note the last 4 digits
011000100
011000100


Reverse these digits and
2
2


evaluate


Calculate thp
t6 = 21
t6 = 21


Add y to twice the sum
0 + 2(2 + 21) = 46
0 + 2(2 + 21) = 46


of these two values


Return decoded value
000101110
000101110









Example 3—Embodiment B—Encode—Palindrome


















Data payload is constructed
0101111001



Use entire value for p
p = 377







Calculate hp




hp
=







-
1

+


1
+

8
·
377




2





=
26












Calculate p − thp





p
-

t
hp


=


377
-


26
*
27

2


=
26












Express hp in binary and place

11010 _ _ _ _ _




at the beginning




Express p − thp in binary and fill
1101001011



in in reverse




Return encoded value
1101001011










Example 3—Embodiment B—Decode—Palindrome
















Original order
Reversed


















Read encoded value
1101001011
1101001011


Compare to reverse
0011101100
0011101100


Select the larger
s = 1101001011
s = 1110010011


Note the first 5 digits
1101001011
1110010011


Use these digits as hp
hp = 26
hp = 26


Note the last 5 digits
1101001011
1101001011


Reverse these digits and evaluate
26
26


Calculate thp
t26 = 351
t26 = 351


Add these two values
26 + 351 = 377
26 + 351 = 377


Return decoded values
0101111001
0101111001









Generalizations of Embodiment B


While symmetric reorderings and symmetric bitwise-XOR transforms can generate a family of solutions from Embodiment B, any permutation transform will allow computation of the full generality of possible mappings. If







z



:





[


0












2

N
-
1



+

2

(




N
2



-
1

)



)




[


0












2

N
-
1



+

2

(




N
2



-
1

)



)






is a permutation of states (any invertible z qualifies), then transforming the payload data by z will generate another valid mapping from Embodiment A or B. For every valid mapping ƒ there is a permutation that converts Embodiment A to ƒ and another that converts Embodiment B to ƒ. Permutations may be generated from a deterministic function, a random bitstream, or a key file by known methods. For N bits there are







(


2

N
-
1


+

2

(




N
2



-
1

)



)

!





permutations, any one of which may be characterized by








log
2



(


2

(

N
-
1

)


+

2

(




N
2



-
1

)



)


!





bits. By Stirling's approximation, this file size is O(N2N). For 20 bits this is a file of just over 1 MB. For larger bit strings, a deterministic function may be more appropriate. Symmetric reorderings, symmetric bitwise-XOR transforms, and combinations thereof constitute some examples of deterministic functions that may be used to generate permutation transforms.


Implementation of Embodiment B


As in Embodiment A, Embodiment B can be implemented via Excel® formulas as generally follows:















Constants:
f = FLOOR( N/2, 1 )



c = CEILING( N/2, 1 )



odd = MOD( N, 2 ) = 1


To encode:
p = FLOOR( data/IF( odd, 2, 1 ), 1 )



y = “”&IF( odd, MOD( data, 2 ), “” )



hp = FLOOR( ( SQRT( 1+8*p ) − 1 )/2, 1 )



encoded = BitValue( BitString( hp,



f )&y&StrRev(BitString( p−(hp+1)*hp/2, f )))


To decode:
s = BitString(MAX( reading,



BitValue( StrRev( BitString( reading, N ) ) ) ), N )



y = IF( odd, VALUE( MID( s, c, 1 )), 0 )



hp = BitValue( LEFT( s, f ) )



p = BitValue( LEFT( StrRev( s ), f ) + hp*(hp+1)/2



decoded = y + p*IF( odd, 2, 1 )









As described above, the foregoing basic algorithm has been implemented as a pair of Excel® functions in VBA, together with a small set of more general functions for handling binary numbers.













Format
Function







=BitSymEncB(Data, N)
Apply f to encode data


=BitSymDecB(Reading, N)
Apply g to decode data


=BitString(Data, N)
Convert numeric data to a string of “1”s and



“0”s


=BitValue(Data)
Convert a string of “1”s and “0”s to numeric



data


=StrRev(Reading, N)
Apply r to reverse a string of “1”s and “0”s









Table 1 below includes a listing of Visual Basic functions used in various embodiments of algorithms and software code arranged to perform the present methods. It should be appreciated the functions below include the operators relevant to the various disclosed embodiments; however, other operators conventionally associated with these functions may also be used.










TABLE 1





FUNCTION ( operators )
Description







CEILING ( number )
returns the smallest integer greater than



or equal to number


CINT ( expression )
converts expression to an integer value


FLOOR ( number )
returns the largest integer less than or



equal to number


INT ( number )
returns integer portion of a number; for



negative number, returns first negative



integer less than or equal to number


LEFT ( text, [number_of_characters] )
extracts a sub string from text starting



from the left most character of a length



number_of_characters


LEN ( text )
returns length of text


LOG ( number, [base] )
returns logarithm of number to a



specified base (if base omitted, base is



10)


MAX ( number1, [number2, . . . number_n] )
returns the largest value from the



numbers provided, i.e., number1, . . .



number_n


MID ( text, start_position, number_of_characters)
extracts a substring from text beginning



at start_position (left most position is 1)



of a length number of characters


MIN ( number1, [number2, . . . number_n] )
returns the smallest value from the



numbers provided, i.e., number1, . . .



number_n


MOD ( number, divisor ) or number MOD divisor
returns remainder after number is divided



by divisor


RIGHT ( text, [number_of_characters] )
extracts a sub string from text starting



from the right most character of a length



number of characters


SQR ( number )
returns square root of number


string1 & string2
concatenate string1 with string2









The following section include a full Visual Basic listing of embodiments of algorithms and software code that are arranged to perform steps as described in the accompanying flowcharts. Functions LSB, StrRev, BitString, BitValue, BitSymEnc (embodiments A and B), and BitSymDec (embodiments A and B) are included below.


LSB (Least Significant Bit—Returns the 0-Indexed jth Least Significant Bit) Function:



















Function LSB(reading, j As Integer) As Integer




 Dim R As Double: R = CDbl(reading)




  If (R < 0) Or (j < 0) Then




   LSB = CVErr(xlErrValue)




 Else




   LSB = Fix(R / 2 {circumflex over ( )} j) − 2 * Fix(R / 2 A (j + 1))




  End If




 End Function










StrRev (String Reverse—Returns the String in Reverse Format) Function:



















Function StrRev(S As String) As String




 Dim i As Integer




 StrRev = ″″




 For i = 1 To Len(S)




  StrRev = Mid(S, i, 1) & StrRev




 Next i




End Function










BitString (Bit Number to String—Converts Numeric Data to a String of “1”s and “0”s) Function:



















Function BitString(reading, N As Integer) As String




 Dim R As Double




 R = CDbl(reading)




 ′ Excel cell value resolution allows for 15 decimal digits




 ′ This is equivalent to 49 binary digits




 ′ N should therefore be 1 to 49




 ′ and R should be 0 to 2{circumflex over ( )}N − 1




 If (N < 1) Or (N > 49) Then




  BitString = CVErr(xlErrValue)




 ElseIf (R < 0) Or (R >= 2 {circumflex over ( )} N) Then




  BitString = CVErr(xlErrValue)




 End If




 BitString = ″″




 Dim j As Integer




 For j = 0 To (N − 1)




  BitString = LSB(R, j) & BitString




 Next j




End Function










BitValue (String to Number—Converts a String of “1”s and “0”s to Numeric Data) Function:



















Function BitValue(S As String) As Double




 Dim i As Integer




 BitValue = 0




 For i = 1 To Len(S)




  Select Case Mid(S, i, 1)




   Case ″0″




    BitValue = 2 * BitValue




   Case ″1″




    BitValue = 2 * BitValue + 1




   Case Else




    BitValue = CVErr(xlErrValue)




    Exit For




  End Select




 Next i




End Function










BitSymEncA (Encodes Data for N-Bit Printed Memory—Embodiment A) Function:
















Function BitSymEncA(value, N As Integer) As Double



 Dim Q As Double: Q = CDbl(value)



 Dim floor As Integer: floor = Int(N / 2)



 Dim ceil As Integer: ceil = −Int(−N / 2)



 If (N < 1) Or (N > 49) Then



  BitSymEncA = CVErr(xlErrValue)



 ElseIf (Q < 0) Or (Q >= 2 {circumflex over ( )} (ceil − 1) * (2 {circumflex over ( )} floor + 1)) Then



  BitSymEncA = CVErr(xlErrValue)



 End If



 Dim S As String: S = BitString(Q, N)



 Dim x As String



 Dim y As String



 Dim d As Double



 If Q = 0 Then



  d = 0



 Else



  d = Log(Q) / Log(2)



 End If



 Select Case d



  Case Is >= N − 1



   x = Mid(S, 2 + floor, floor − 1)



   y = ″0″ & Right(S, ceil − floor) & ″1″



  Case Is < ceil



   x = Mid(S, floor + 1, floor)



   y = Right(S, ceil − floor)



  Case Else



   Dim i As Integer: i = Int(d − ceil + 1)



   x = Mid(S, floor − i + 2, floor − i − 1)



   y = ″0″ & Right(S, 2 * i + ceil − floor) & ″1″



 End Select



 BitSymEncA = BitValue(X & y & StrRev(X))



End Function









BitSymDecA (Decodes Data for N-Bit Printed Memory—Embodiment A) Function:
















Function BitSymDecA(reading, N As Integer) As Double



 ′ Excel cell value resolution allows for 15 decimal digits



 ′ This is equivalent to 49 binary digits



 ′ N should therefore be 1 to 49



 ′ and R should be 0 to 2{circumflex over ( )}N − 1



 Dim R As Double: R = CDbl(reading)



 If (N < 1) Or (N > 49) Then



  BitSymDecA = CVErr(xlErrValue)



 ElseIf (R < 0) Or (R >= 2 {circumflex over ( )} N) Then



  BitSymDecA = CVErr(xlErrValue)



 End If



 BitSymDecA = 0



 Dim j As Integer



 Dim isPalindrome As Boolean: isPalindrome = True



 Dim floor As Integer: floor = Int(N / 2)



 Dim ceil As Integer: ceil = −Int(−N / 2)



 For j = 0 To ceil − 1



  If (LSB(R, N − 1 − j) = LSB(R, j)) Then



   BitSymDecA = 2 * BitSymDecA + LSB(R, j)



  Else



   isPalindrome − False



   Exit For



  End If



 Next j



 Dim k As Integer



 Dim i As Integer: i = 1 + (2 * floor − 2 − j) Mod (floor)



 Dim kMax As Integer



 If isPalindrome Then



  kMax = floor



 Else



  kMax = N − j − 2



 End If



 If LSB(R, j) = 1 Then



  For k = j + 1 To kMax



   BitSymDecA = 2 * BitSymDecA + LSB(R, N − k − 1)



  Next k



 Else



  For k = j + 1 To kMax



   BitSymDecA = 2 * BitSymDecA + LSB(R, k)



  Next k



 End If



 If Not isPalindrome Then



  BitSymDecA = BitSymDecA + 2 {circumflex over ( )} (i + ceil − 1)



 End If



End Function









BitSymEncB (Encodes Data for N-Bit Printed Memory—Embodiment B) Function:
















Function BitSymEncB(value, N As Integer) As Double



 Dim odd As Integer: odd = N Mod 2



 Dim Q As Double: Q = CDbl(value)



 If (N < 1) Or (N > 49) Then



  BitSymEncB = CVErr(xlErrValue)



 ElseIf (Q < 0) Or (Q >= 2 {circumflex over ( )} (ceil − 1) * (2 {circumflex over ( )} floor + 1)) Then



  BitSymEncB = CVErr(xlErrValue)



 End If



 Dim S As String: S = BitString(Q, N)



 Dim p As Double: p = (Q − odd * CInt(Right(S, 1))) / (1 + odd)



 Dim hp As Double: hp = Int((Sqr(1 + 8 * p) − 1) / 2)



 Dim f As Integer: f = Int(N / 2)



 BitSymEncB = BitValue(BitString(hp, f) & Right(S, odd) &



 StrRev(BitString(p −



(hp + 1) * hp / 2, f)))



End Function









BitSymDecB (Decodes Data for N-Bit Printed Memory—Embodiment B) Function:
















Function BitSymDecB(reading, N As Integer) As Double



 Dim odd As Integer: odd = N Mod 2



 Dim R As Double: R = CDbl(reading)



 If (N < 1) Or (N > 49) Then



  BitSymDecB = CVErr(xlErrValue)



 ElseIf (R < 0) Or (R >= 2 {circumflex over ( )} N) Then



  BitSymDecB = CVErr(xlErrValue)



 End If



 Dim S As String: S = BitString(R, N)



 Dim f As Integer: f = Int(N / 2)



 Dim a As Double: a = BitValue(Left(S, f))



 Dim b As Double: b = BitValue(StrRev(Right(S, f)))



 Dim hp As Double



 If a > b Then



  hp = a



 Else



  hp = b



 End If



 ′ p − t_hp = Min(a, b) = a + b − hp



 ′ t_hp = hp * (hp + 1) / 2



 ′ t_hp − hp = hp *(hp − 1) / 2



  BitSymDecB = (a + b + hp * (hp − 1) / 2) * (1 + odd) +



  odd * CInt(Mid(S, −Int(−N



/ 2), 1))



 End Function









Alternate Embodiments


An alternate embodiment, hereinafter referred to as Strategy 1, is depicted in FIG. 2 where printed memory label 40 is made asymmetrical, i.e., the leads in the upper portion of label 40 are arranged differently than the leads in the lower portion of label 40. Thus, the contacts in the upper left corner may be used to determine the orientation of label 40 in a reader. Such an arrangement requires the use of switchable contacts to reconfigure the reader according to the orientation of the label. Strategy 1 causes increased cost for the use of printed memory labels, especially for the reader device.


Another alternate embodiment, hereinafter referred to as Strategy 2, is a simple software approach. A symmetrically oriented pair of bits is chosen and then 0 and 1 are written to those bits, respectively. This embodiment uses two bits of memory to establish what is essentially one bit of information, i.e., 0 represents a first orientation and 1 represents a second bit of orientation. For example, the printed memory could include bit 0=0 and bit 19=1, or any symmetrically oriented pair. Thus, the reader could detect the orientation of the symmetrical pair of bits and determine orientation of the label accordingly.


Generally, the presently disclosed algorithms and methods provide a coding scheme for capturing just over N−1 bits of information in an N-bit memory cell, such that reversing the bit order of the N-bits preserves the N−1 bits payload data. Moreover, the present methods can be directly extended to cover the entire set of solutions to the problem statement via transformations including permutation transformations, symmetric bit-swapping transformations and symmetric bit-flipping transformations. The disclosed methods permit payload data to be robust to, i.e., unaffected by, 180° rotation of the PM carrier body. The methods enable a single reader to register bodies of various configurations. The methods may be easily modified for a particular application, device, or user, while also providing a lower cost option than building a reader compatible with both orientations. Moreover, the methods are more efficient than an approach dedicating two bits to orientation determination.


This technology may be used as an optional part of printed memory solutions, as an alternative to more expensive readers, reduced bit capacity, or mechanical means of enforcing orientation. For example, one use may be as a key enabler to use a single reader for a wallet card before and after it has been punched out of its display card. Moreover, although the encoding and decoding actions are in some embodiments described as actions performed by separate devices, e.g., a printed memory reader or a printed memory writer, it is within the scope of the present disclosure to perform both encoding and decoding actions within a common device or unit.


It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.

Claims
  • 1. A printed memory reader adapted to determine an original value from a printed memory device comprising a plurality of contact pads and an encoded value created by encoding the original value, the encoded value comprises N bits of data, where N is equal to a number of bits of data stored in the printed memory device, the printed memory reader comprising: a plurality of probes arranged to contact the plurality of contact pads;a memory storage element comprising instructions programmed to execute the steps: a) reading the encoded value or an inverse encoded value from the printed memory device using the plurality of probes to obtain a read value, wherein equivalency between the encoded value and the inverse encoded value is not required; and,b) decoding the read value to obtain a decoded value equal to the original value; and,a processor arranged to execute the instructions.
  • 2. The printed memory reader of claim 1 wherein decoding the read value comprises determining when the read value is a palindrome value.
  • 3. The printed memory reader of claim 1 wherein when the read value is not a palindrome value, decoding the read value comprises determining when the read value is the encoded value or the inverse encoded value.
  • 4. The printed memory reader of claim 3 wherein decoding the read value comprises: determining when the read value is larger than an inverse of the read value; or,determining when the read value is smaller than the inverse of the read value.
  • 5. The printed memory reader of claim 3 wherein determining when the read value is the encoded value or the inverse encoded value comprises: a) comparing symmetrically oriented bit pairs beginning with an outermost pair and moving inwardly until bits of a compared symmetrically oriented bit pair are non-identical bits; and,b) using the non-identical bits to determine when the read value is the encoded value or the inverse encoded value.
  • 6. The printed memory reader of claim 1 wherein when N is an even number, decoding the read value is performed according to: a) determining the larger of the read value and an inverse of the read value to establish the encoded value;b) determining a triangular number indexed by a first half of the encoded value;c) reversing a second half of the encoded value to form a reversed second half value; and,d) adding the triangular number to the reversed second half value to obtain the decoded value,
  • 7. The printed memory reader of claim 1 wherein the printed memory reader is configured to read the encoded value or the inverse encoded value that is a palindrome and configured to read the encoded value or the inverse encoded value that is not a palindrome.
  • 8. A printed memory writer adapted to store an encoded value on a printed memory device comprising a plurality of contact pads, the printed memory writer comprising: a plurality of probes arranged to contact the plurality of contact pads;a memory storage element comprising instructions programmed to execute the steps: a) encoding an original value to form the encoded value comprising N bits of data, where N is equal to a number of bits of data stored in the printed memory device, such that an alternate value cannot yield an alternate encoded value equal to the encoded value or an inverse encoded value, wherein equivalency between the encoded value and the inverse encoded value is not required; and,b) storing the encoded value on the printed memory device; and,a processor arranged to execute the instructions.
  • 9. The printed memory writer of claim 8 wherein when N is an even number, the encoded value is calculated according to: a) determining a largest triangular number that is less than or equal to the original value, the triangular number comprising an index;b) calculating a difference between the original value and the largest triangular number;c) reversing the difference to form an inverse difference; and,d) combining, in order, the index and the inverse difference to form the encoded value,
  • 10. The printed memory writer of claim 8 wherein the printed memory writer is configured to store the encoded value that is a palindrome and configured to store the encoded value that is not a palindrome.
  • 11. A method of using a printed memory device for storage of an original value comprising: a) encoding the original value to form an encoded value comprising N bits of data, where N is equal to a number of bits of data stored in the printed memory device, such that an alternate value cannot yield an alternate encoded value equal to the encoded value or an inverse encoded value, wherein equivalency between the encoded value and the inverse encoded value is not required; and,b) storing the encoded value on the printed memory device.
  • 12. The method of using a printed memory device of claim 11 wherein when N is an even number, encoding the original value is performed according to: a) determining a largest triangular number that is less than or equal to the original value, the triangular number comprising an index;b) calculating a difference between the original value and the largest triangular number;c) reversing the difference to form an inverse difference; and,d) combining, in order, the index and the inverse difference to form the encoded value,
  • 13. The method of using a printed memory device of claim 11 wherein the step of encoding is configured to permit the encoded value to be a non-palindrome value.
  • 14. A method of using a printed memory device for retrieval of an original value, wherein the original value is encoded to form an encoded value comprising N bits of data, where N is equal to a number of bits of data stored in the printed memory device, the method comprising: a) reading the encoded value or an inverse encoded value using a printed memory reader to obtain a read value, wherein equivalency between the encoded value and the inverse encoded value is not required; and,b) decoding the read value to obtain the original value.
  • 15. The method of using a printed memory device of claim 14 wherein the step of decoding the read value comprises determining when the read value is a palindrome value.
  • 16. The method of using a printed memory device of claim 14 wherein when the read value is not a palindrome value, the step of decoding the read value comprises determining when the read value is the encoded value or the inverse encoded value.
  • 17. The method of using a printed memory device of claim 16 wherein decoding the read value comprises: determining when the read value is larger than an inverse of the read value; or,determining when the read value is smaller than the inverse of the read value.
  • 18. The method of using a printed memory device of claim 16 wherein determining when the read value is the encoded value or the inverse encoded value comprises: a) comparing symmetrically oriented bit pairs beginning with an outermost pair and moving inwardly until bits of a compared symmetrically oriented bit pair are non-identical bits; and,b) using the non-identical bits to determine when the read value is the encoded value or the inverse encoded value.
  • 19. The method of using a printed memory device of claim 14 wherein when N is an even number, decoding the read value is performed according to: a) determining the larger of the read value and an inverse of the read value to establish the encoded value;b) determining a triangular number indexed by a first half of the encoded value;c) reversing a second half of the encoded value to form a reversed second half value; and,d) adding the triangular number to the reversed second half value to obtain the decoded value,
  • 20. The method of using a printed memory device of claim 14 wherein the step of reading is configured to permit the encoded value to be a non-palindrome value.
CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 62/214,606, filed Sep. 4, 2015, which application is incorporated herein by reference.

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Related Publications (1)
Number Date Country
20170068830 A1 Mar 2017 US
Provisional Applications (1)
Number Date Country
62214606 Sep 2015 US