IBM RT Series Hardware Reference Manual page 329

TNL SN20-9844 (March 1987) to 75X0235
I/O Address to Equivalent Queue Pointer Value Conversion
DEVICE
Y BIT X WORD
DECODE ADDRESS ADDRESS
0
1 1 0 1 1
o
0
Bits 7 -16 Bits 17 -22
I/O CHANNEL ADDRESS
0
:~
Y BIT
X WORD (LEAST SIGNIFICANT
ADDRESS ADDRESS 4 BITS OF X ADDRESS
10 BITS 6 BITS ARE SET TO ZEROES)
16 BIT QUEUE POINTER
VALU~
o
Extended Monochrome Graphics Adapter 17