pixelator/PSI File Type.txt at master · techcompliant/pixelator · GitHub

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Pixelated Simple Image File Type (PSI)

    The files of this type are used to store images for LEM1802 monitor.

    [!] To clear things up: in this document "should" means just a
recommendation, whereas "must" means imperative.

    Please also notice, that grammar here may be far from good. Sorry.

    File structure (size is given in words, total size is 673 words):
    +------+-------------------+
    | Size | Name              |
    +------+-------------------+
    | 1    | magic_number      |
    +------+-------------------+
    | 15   | file_name         |
    +------+-------------------+
    | 2    | background_symbol |
    +------+-------------------+
    | 254  | image_font        |
    +------+-------------------+
    | 16   | image_palette     |
    +------+-------------------+
    | 1    | border_color      |
    +------+-------------------+
    | 384  | video_ram         |
    +------+-------------------+

1) magic_number
    The magic number is 0x5034. It defines the file's type as PSI.

2) file_name
    Defines the file's original name (independent from the File System).
Allowed characters: 0x20 - 0x7e (ASCII). The maximum length of the name is 15
characters, any unused characters at the end of the name must be set to null.
The minimum length of the name is 0 characters, which means that there is no
original name.

3) background_symbol
    Defines a symbol which is used as background for the image. It should be
null (but can be any symbol).

4) image_font
    Defines 127 symbols (2 words per symbol). These symbols are divided into
USED and UNUSED.
    USED symbols have at least one location on the screen. USED symbols must be
unique. USED symbols must be not null.
    UNUSED symbols do not have any locations on the screen. UNUSED symbols must
be null.

5) image_palette
    Defines 16 colors. The first color should be contrast to the sixteenth.
In other words, the "black-by-default" color should be contrast to the
"white-by-default" one.

6) border_color
    Defines the number of border color. The number refers to image_palette.

7) video_ram
    Defines locations and colors (and blinking) of symbols. There should be one
USED symbol with only one location OR one UNUSED symbol.

    Additional information can be found in LEM1802's documentation ("Font ram",
"Palette ram" and "Video ram" sections). The documentation can be found here:
http://dcpu.com/monitor/

Fen-ok (http://0x10cforum.com/profile/4855939)
27 July 2013