VGA text mode cells are stored in memory as 2 bytes. The low byte contains an ASCII code point, and the high byte contains text attributes.

The memory address for VGA's text screen is 0xB8000.

Example Code

Here is some C code to break a cell (a uint16_t) into its component parts:

// get ascii code point
uint8_t code = (uint8_t)(cell & 0xFF);

// get attributes
uint8_t attr = (uint8_t)(cell >> 8);

// break out attributes
uint8_t blink = (attr >> 7) & 0x01;
uint8_t bgcolor = (attr >> 4) & 0x07;
uint8_t fgcolor = attr & 0x0F;

• blink is a boolean controlling whether the text in that cell should blink. (the blink frequency is about 4.380 Hz).
• bgcolor in an index into the 16 color EGA palette controlling the background color of the cell. Since it only uses 3 bits, you only have access to the lower eight colors.
• fgcolor is an index into the 16 color EGA palette controlling the text color. Since it is 4 bits wide, it can use the whole 16 color range.

EGA Palette

Further Reading

• StackExchange: What are the blinking rates of the caret and of blinking text on PC graphics cards in text mode?
• Wikipedia: VGA text mode