Autodial No. 301A/302A (Card Callmakers)   I love these! The idea is that you encode a telephone number onto a card and build up a collection of all your frequently dialed numbers. To make a call you lift the handset of the telephone and drop a card into the top of the machine. The card is allowed to drop (in a controlled manner) through the machine which reads the number off the card a line at a time and dials the digits accordingly. The quirky part (the bit which fascinates me) is how the telephone number is encoded onto the cards: For example, say you wanted to encode 020 1234. Starting at the top of the card with the last digit (i.e. 4), you subtract the digit from 16 and encode the result (12) in binary form on the card by punching out the relavent holes. So for the above number you would end up with: Digit 16 - Digit Binary 4 12 1100 3 13 1101 2 14 1110 1 15 1111 0 6* 0110 2 14 1110 0 6* 0110 * Note: 0 is counted as 10. For more information see Autodial No. 301A/302A (Card Callmaker)

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