M69000 Asiliant Technologies, M69000 Datasheet - Page 293

• Manufacturer Part Number: M69000
• Manufacturer: Asiliant Technologies

Specifications of M69000

• Lead Free Status / Rohs Status: Supplier Unconfirmed

17-10
9-8
7-0
&+,36
Starting Point Select
Bit-Wise Operation Select
69000 Databook
These two bits are used to select which of the four corners to use as the starting point in
reading and writing graphics data in a BitBLT operation. Normally, the upper left corner is
used. However, situations involving an overlap of source and destination locations (this
usually occurs when the source and destination locations are both on-screen) often require
the use of a different corner as a starting point. It should be remembered that the
addresses specified for each piece of graphics data used in a BitBLT operation must point
to the byte(s) corresponding to whichever pixel is at the selected starting point. If the
starting point is changed, then these addresses must also be changed. See the chapter on
the BitBLT engine for more information.
These 8 bits are meant to be programmed with an 8-bit code that selects which one of 256
possible bit-wise operations is to be performed by the BitBLT engine during a BitBLT
operation. These 256 possible bit-wise operations and their corresponding 8-bit codes are
designed to be compatible with the manner in which raster operations are specified in the
standard BitBLT parameter block normally used in the Microsoft Windows environment,
without translation. See the section on the BitBLT engine for more information.
Note: Bit 12 of this register must be set to 0 whenever a bit-wise operation is selected that
does not use source data.
9 8
0 0 Upper Left Corner -- This is the default after reset.
0 1 Upper Right Corner
1 0 Lower Left Corner
1 1 Lower Right Corner
Bit
Subject to Change Without Notice
Corner Selected as the Starting Point
BitBLT Registers
Revision 1.3 8/31/98