March 2024

By aaron.axvig, Fri, 03/08/2024 - 08:01

The kids' toy "LeapFrog Fridge Phonics" has letter pieces that mount in a decoder, which then say different things depending on which letter you mounted.  Of course this requires some system for describing each letter, which I have documented below.

There are six bits.  I will mark the presence of a bump as 1, and no bump as a 0.  A couple pieces were missing but I am reasonably certain I have deduced those values correctly (guesses in parenthesis).  I have recorded them in what seems like "most-significant bit on the left" order.  If you have the letter upright and look at the back at the bumps along the bottom, this is the matching order.

All sequences ending in 00 were skipped.  And I suppose any starting with 00 were also skipped, since A starts off the sequence with the lowest binary value that would satisfy both criteria.  I'm thinking that the mechanics of the toy work best when the force is distributed on both ends of the pieces, hence always wanting at least one bump at or next to each end.

I find the two-code gap between N and O to be a real puzzle.  It must be for Ñ but I found a video of a Spanish version of the toy and the Ñ was just an aside drawn on the N.

The characters do actually line up with the characters in the ASCII binary table if:

  • Shift a digit in from the left.
  • Perform some modulo 3 adjustment to compensate for the gaps.
  • Compensate for the Ñ gap (module 14 adjustment?).
A(010001)
B 010010
C 010011
  010100
D(010101)
E 010110
F 010111
  011000
G 011001
H 011010
I 011011
  011100
J 011101
K 011110
L 011111
  100000
M 100001
N 100010
  100011
  100100
O 100101
P 100110
Q 100111
  101000
R 101001
S 101010
T 101011
  101100
U 101101
V 101110
W 101111
  100000
X 110001
Y 110010
Z 110011
  110100