
8: HARDWARE CURSOR/INK LAYER
S1D13806 SERIES PROGRAMMING NOTES
EPSON
2-29
AND EXAMPLES (X28B-G-003-01)
8HARDWARE CURSOR/INK LAYER
8.1 Introduction
The S1D13806 supports either a Hardware Cursor or an Ink Layer for the LCD, and either a Hard-
ware Cursor or an Ink Layer for the CRT/TV. The LCD and CRT/TV are supported independently,
so it is possible to select combinations such as a Hardware Cursor on the LCD and an Ink Layer on
the CRT/TV.
A Hardware Cursor improves video throughput in graphical operating systems by off-loading much
of the work typically assigned to software. For example, consider the actions which must be per-
formed when the user moves the mouse. On a system without hardware support, the operating sys-
tem must restore the area under the current cursor position, save the area under the new location, and
finally draw the cursor shape. Contrast that with the hardware assisted system where the operating
system must simply update the cursor X and cursor Y position registers.
An Ink Layer is designed to support stylus or pen input. Without an ink layer, the operating system
must save the area of the display buffer (possibly all) where pen input is to occur. After the system
recognizes the characters entered, the display would have to be restored and the characters redrawn
in a system font. When an Ink Layer is present, the stylus path is drawn in the Ink Layer where it
overlays the displayed image. After character recognition finishes the display is updated with the
new characters and the ink layer is simply cleared. Saving and restoring the display data is not
required providing faster throughput.
The S1D13806 Hardware Cursor/Ink Layer supports a 2 bpp (four color) overlay image. Two of the
available colors are transparent and invert. The remaining two colors are user definable.
The Hardware Cursor uses many of the same registers as the Ink Layer. Additionally, the cursor has
positional registers for movement. The cursor resolution is 64
× 64 at a color depth of 2 bpp. The Ink
Layer resolution is the width of the display by the height of the display at a color depth of 2 bpp.
Both the Hardware Cursor and the Ink Layer use the same pixel values to select colors. The Hard-
ware Cursor requires 1024bytes of display buffer and the Ink Layer requires (display width
× dis-
play height
÷ 4) bytes of display buffer.