IBM RT Series Hardware Reference Manual page 338

TNL SN20-9844 (March 1987) to 75X0235
Logical Write Function Performed
Functional
Value
0
Replace destination with zeros
1
I/O data 'AND' destination
2
, I/O data 'AND' destination
3
Reserved
4
Reserved
5
Reserved
6 Reserved
7
Reserved
8
I/O data 'AND', destination
9
Replace destination with I/O data
A I/O data 'XOR' destination
11 I/O data 'OR' destination
12
Reserved
13
Reserved
14
,1/0 data 'OR' ,destination
15
Replace destination with ones
Note: Destination refers to the bit map data.
Figure 18. Logical Functions
26 Extended Monochrome Graphics Adapter