M69000 Asiliant Technologies, M69000 Datasheet - Page 180

• Manufacturer Part Number: M69000
• Manufacturer: Asiliant Technologies

Specifications of M69000

• Lead Free Status / Rohs Status: Supplier Unconfirmed

XR20
read/write at I/O address 3D7h with index at I/O address 3D6h set to 20h
7-6
5-4
3-2
1
0
&+,36
7
Reserved
These bits always have the value of 0 when read.
BitBLT Engine Color Depth
When bit 23 of the BitBLT Control Register (BR04) is set to 0, these two bits configure the BitBLT
engine for one of three possible color depths. If bit 23 of the BitBLT Control Register (BR04) is set
to 1, then this function is performed by bits 25 and 24 of that same register.
recommended that the color depth of the BitBLT engine be set to match the color depth to which
the graphics system has been set whenever possible.
The choice of color depth configures the BitBLT engine to work with one, two or three bytes per
pixel. This directly affects the number of bytes of graphics data that the BitBLT engine will read and
write for a given number of pixels. In the case of monochrome source or pattern data, this setting
directly affects the color depth into which such monochrome data will be converted during the color
expansion process.
If the graphics system has been set to a color depth that is not supported by the BitBLT engine, then
it is strongly recommended that the BitBLT engine not be used. See appendix B for more
information.
Reserved (Writable)
These bits should always be written to with the value of 0.
BitBLT Reset
0: Writing a value of 0 to this bit permits normal operation of the BitBLT engine. This is the default
value after reset.
1: Writing a value of 1 to this bit resets the BitBLT engine.
BitBLT Engine Status
0: Indicates that the BitBLT engine is idle. This is the default after reset.
1: Indicates that the BitBLT engine is busy.
Reserved
69000 Databook
(00)
BitBLT Configuration Register
6
Bits
5 4
0 0
0 1
1 0
1 1
BitBLT Engine Color Depth Selected
8 bits per pixel (1 byte per pixel) -- This is the default after reset.
16 bits per pixel (2 bytes per pixel)
24 bits per pixel (3 bytes per pixel)
Reserved
5
BitBLT Engine
Color Depth
Subject to Change Without Notice
(00)
Extension Registers
4
Reserved (Writable)
3
(00)
2
BitBLT
Reset
(0)
Revision 1.3 8/31/98
1
It is strongly
BitBLT
Status
(0)
0
14-13