Figure 9-2 on the following page demonstrates how a special character is designed at a PLATO terminal. The author moves the cursor on an 8 x 16 grid to specify which dots are to be lit. The author can inspect “in the small” the appearance of the character he designs “in the large”. The letter shown at the top of the page is the key with which this character will be associated when typing in the alternate font, just as character “д” is associated with key “d” in “charset russian”. The character pattern is stored in such a way that the author can (at any later time) recall the pattern and modify it. A character set can contain up to 126 special characters or as few as one or two characters.

Below is an example from lesson AID which displays pictures of cars:

Note the composition of the image of a hatchback as “89-+□a”

This figure shows how an author can create several 8 x 16 characters at once to be used together or separately. This option is particularly helpful when designing character-mode pictures.

This is the composition of the back of the “hatchback”:

Your own character set will be stored in an electronic storage area assigned to you. Such storage areas are called “lesson spaces” because they mainly hold TUTOR statements which describe a lesson to be administered to students by PLATO. Your lesson space might be called “italian3” and it is by this name that you refer to the lesson space when you want to look at the TUTOR statements or change them. Within this lesson space you can also have one or more character sets, which you will have named. Suppose in lesson space “italian3” you have stored a character set named “rome”. In this case, the TUTOR statement used to transmit this character set to a terminal is:

The same format holds for linesets.

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