sed1355 ETC-unknow, sed1355 Datasheet - Page 189

• Manufacturer Part Number: sed1355
• Description: Sed1355 Embedded Ramdac Lcd/crt Controller
• Manufacturer: ETC-unknow

Epson Research and Development
Vancouver Design Center
7 Hardware Cursor
7.1 Introduction
7.2 Registers
Programming Notes and Examples
Issue Date: 99/04/27
REG[27h] Ink/Cursor Control Register
Ink/Cursor
Mode
bit 1
Ink/Cursor
Mode
bit 0
The SED1355 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 SED1355 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.
There are a total of eleven registers dedicated to the operation of the hardware cursor/ink layer.
Many of the registers need only be set once. Others, such as the positional registers, will be updated
frequently.
The Ink/Cursor mode bits determine if the hardware will function as a hardware cursor or as an ink
layer. See Table 7-1: for an explanation of these bits.
When cursor mode is selected the cursor image is always 64x64 pixels. Selecting an ink layer will
result in a large enough area to completely cover the display.
bit 7
0
0
1
1
n/a
Register [27h]
Table 7-1: Ink/Cursor Mode
n/a
bit 6
0
1
0
1
Cursor High
Threshold
bit 3
Cursor High
Operating
Reserved
Threshold
Inactive
Cursor
Mode
bit 2
Ink
Cursor High
Threshold
bit 1
X23A-G-003-05
Cursor High
Threshold
bit 0
SED1355
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