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Epson Research and Development
Page 43
Vancouver Design Center
Programming Notes and Examples S1D13505
Issue Date: 01/02/05 X23A-G-003-07
7 Hardware Cursor/Ink Layer
7.1 Introduction
The S1D13505 provides hardware support for a cursor or an ink layer. These features are
mutually exclusive and therefore only one or the other may be active at any given time.
A hardware cursor improves video throughput in graphical operating systems by off-
loading much of the work typically assigned to software. Take the actions which must be
performed when the user moves the mouse. On a system without hardware support, the
operating system must restore the area under the current cursor position then 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 used to support stylus or pen input. Without an ink layer the operating
system would have to save an area (possibly all) of the display buffer where pen input was
to occur. After the system recognized the user entered characters, the display would have
to be restored and the characters redrawn in a system font. With an ink layer the stylus path
is drawn in the ink layer, where it overlays the displayed image. After character recognition
takes place the display is updated with the new characters and the ink layer is simply
cleared. There is no need to save and restore display data thus providing faster throughput.
The S1D13505 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.