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rgb_video_card

Logisim RGB video component with a character generator ROM.

This graphics card is an Arduino like LCD. The display is 128x64 pixel dots.

Each character makes up 5 by 8 dots, Hence the aspect ratio is 21:7 (with padding on each side).

alt_text

Customizable character set. Mine is surely awful. Generate your own char set here. Make sure to use hex values.

CGROM

The Character Generator ROM is pre-written with Upper case alphabet A-Zand numerical 0-9.

To display a char, simply address the ROM with the char ASCII code.

Eg:

0x41 is for the letter A, 0x30 is for 0 and so on.

Built-in cursor management:

The aspect ration is 21 by 7. So on the x axis column, you can display 21 char (0 to 20) and on the y axix row, 7 char (0 to 6).

Simply set the desired cursor position (x, y) and address the cgram to display the desired char.

At the end of a char fully displayed, a stop flag is raised and need to be cleared reset pin of a register. Simply write 1 and 0 (push button like) to start displaying new char again.

Clear pixel

Simply write monochrome 4-bit color code 0000 to overwrite current pixel with black color. Different colors can be used depending on the color code 1

alt text

Missing features

  • Clear portion of the display
  • Lower case ASCII char
  • Support for extended ASCII char
  • Punctuation char
  • Use RGB colors (monochrome 4-bit in use as of now)