The keyboards — the Japanese layout and the ADM-3A — are bit-paired, meaning that the characters on an unshifted and shifted key differ in exactly one bit in th

The keyboards — the Japanese layout and the ADM-3A — are bit-paired, meaning that the characters on an unshifted and shifted key differ in exactly one bit in the ASCII encoding. SP ! " # $ % & ' ( ) * + , - . / 0 1 2 3 4 5 6 7 8 9 : ; < = > ? @ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [ \ ] ^ _ ` a b c d e f g h i j k l m n o p q r s t u v w x y z { | } ~ DEL Shift toggles bit 4 of the numeric and low punctuation keys (codes < 0x40), and bit 5 of the alphabetic and high punctuation keys. This made terminals easier and cheaper to build, in the days before cheap microprocessors, when encoding was done in discrete logic or, like the Teletype 33, mechanically.