IBM RT Series Hardware Reference Manual page 352

TNL SN20-9844 (March 1987) to 75X0235
Rectangular Source and Destination Graphic Operation Types
Two rectangular regions of pels (source-destination) are operated on by the graphic operation
processor. The graphic operation reads the source and either read-modify-writes or writes the
destination. The source data is to either replace the destination data, as in a copy operation or,
merge data as in an AND, OR or XOR merge operations.
These graphic operation types require both a source and a destination X, Y (:lddress pair. The
address pair depicts the source corner point (XS,YS) and the destination corner point (XD,YD).
The size (DX,DY) of the rectangle must also be specified.
The queue load for these graphic operation types is up to seven 16-bit words as shown below.
The queue load below represents a rectangular area of pels being moved down by one pel. The
rectangular area defined is 1024 x 767.
Queue Queue Action By Register Register
Address Data Queue Processing Start Min Max
Que Ptr X'7000' Load XD into R 7 XD= 1024 1 1024
Que Ptr-l
X'A300'
Load YD into RA YD=768 1 1024
Que Ptr-2 X'5000'
Load XS into R5
XS = 1024
1
1024
Que Ptr-3 X'42FF' Load YS into R4 YS = 767 1 1024
Que Ptr-4
X'9000'
Load DX into R9 DX= 1024 1
DX=X
Que Ptr-5 X'02FF' Load DY into RO DY=767
1
DY=Y
Que Ptr-6 X'D300' Execute copy/scroll
Note: Unpredictable results might occur if DX
>
XD,DY
>
YD,DX
>
XS or DY
>
YS.
40 Extended Monochrome Graphics Adapter