| We have seen, in the History of the Computer | | | | sprocket hole was punched in the tape so that it |
| series, how machine code is used to operate a | | | | could be moved through the reader.As we know |
| computer so that it can use 1s and 0s to interpret a | | | | from our look at binary codes, 5 bits will give us a |
| program's intentions. But what about a code for | | | | total of 31 characters (1+2+4+8+16) plus zero. With |
| human communication with the computer? We can | | | | 26 being used for the English alphabet, the other |
| variously write and read to and from different media, | | | | characters are used for Carriage Return, Line Feed, |
| such as paper tape, magnetic tape, disk or teletype, | | | | etc. These are needed to operate the typewriter |
| but we need some means of converting English (or | | | | used to print out the information. Another character, |
| another language) into a form which can be carried | | | | Bel was used to ring a bell on the typewriter to alert |
| on these media.You may recall the old Western | | | | the operator.Later a Shift character was |
| movies where the James gang shoot the telegraph | | | | incorporated, similar to the Shift key on a typewriter, |
| operator so he can't call the Marshall for help. Or the | | | | so that following characters would indicate numbers. |
| movies about the '29 Wall St crash where the | | | | Another shift code would switch back to letters. This |
| tycoon reads the bad news on the ticker tape and | | | | Baudot Code was used on teletype machines to |
| promptly leaps out of 32nd floor window. Both of | | | | transmit data from one location to another. This was |
| these are early examples of a code being used on a | | | | later accomplished by first punching the tape, and |
| medium. In this case morse code on the telegraph, | | | | then transmitting it by feeding it through a 'high |
| and an analog code produced from a keyboard at | | | | speed' reader. These speeds were gradually |
| the transmitting point, also sent by telegraph. The | | | | increased as the technology improved, and were |
| ticker tape, so called because of the noise made by | | | | generally expressed as the 'Baud Rate', roughly |
| the printing mechanism, carried the Stock Code, as | | | | equivalent to bits per second, also named after |
| used in today's stock market, and a quote.A later | | | | Baudot. Most problems came from punching errors |
| code used for paper tape, the baudot code, named | | | | and synchronising transmitter and receiver.In part 2 |
| after the French inventor, Baudot, was a five bit | | | | we look at how codes are used in computers.Tony is |
| code, punched across the tape, giving a 1s and 0s | | | | an experienced computer engineer. He is currently |
| pattern to make up the 26 letters of the alphabet. | | | | webmaster and contributor to . A set of diagrams |
| The tape was an inch wide and came on big reels. A | | | | accompanying these articles may be seen at . |