Dot matrix LCD : the CGRAM
Certainly it is a job that can be considered tedious to create sequences of bytes to define a symbol, because it may be difficult to understand if the symbol created will be presented in an understandable and effective in the display.
Fortunately, there is help on the Web and we avoid manual work that could be inaccurate, because there are many utilities to facilitate the preparation of codes for the characters that 'You can load in CGRAM. For example:
In 'picture above, the prompt of' Proton efficient computer that provides support for the 8-character programmable CGRAM and indicates the corresponding code in BASIC that must be loaded to write to that location. A panel with the matrix 5 x 8 allows you to select a graphic with the mouse the pixels to be turned on in order to have a pre-view of how the character presented on the display.
In 'example above is written all eight lines that make up the character, then all 8 bytes are significant.
Note: The first two bytes of the line PRINT correspond to commands needed to access the first location (0) of the CGRAM.