IBM RT Series Hardware Reference Manual page 335

TNL SN20-9844 (March 1987) to 75X0235
I/O Address Access Function Performed
X'ODIA'
Read Disable Video Data Output
X'ODIC' Read Reserved
X'ODIE' Read
Reserved
X'OD20' Read Reserved
X'OD22'
Read Reserved
X'OD24'
Read Reserved
X'OD26' Read Reserved
H'OD28' Read Reserved
Figure 15 (Part 2 of 2). I/O Address Function Table
Interrupt Acknowledge Register (Address X'06F3')
This is a write-only register and the data is of no significance. This address signals that a
pending interrupt was serviced and re-enables the adapter interrupt request pulse generating
circuit.
Reset Frame Sync Interrupt Register (Address X'OD22')
This is a write-only register and the data is of no significance. This address resets any pending
frame sync interrupt (interrupt level 11). Interrupt 11 is a shared interrupt.
Reset Graphic Operation Interrupt Register (Address X'OD24')
This is a write-only register and the data is of no significance. This address resets any pending
graphic operation interrupt (interrupt level 11). Interrupt 11 is a shared interrupt.
Extended Monochrome Graphics Adapter
23