IBM RT Series Hardware Reference Manual page 337

TNL SN20-9844 (March 1987) to 75X0235
Write Number
Count of Bits
(Hex) Written
0 16
1 1
2 2
3 3
4
4
5 5
6 6
7 7
8 8
9 9
A
10
B
11
C
12
D
13
E
14
F
15
Figure 17. Write Count Mask
Extended Monochrome Graphics Adapter 25