IBM BDM-610000049 DIO-Control I/O Address 453h-Read Access, Multi-Function at Address 452h1

Table 47 DIO-Control I/O Address 453h—Read Access

D7 D6 D5 D4 D3 D2 D1 D0

Strobe 0 Status		Strobe 1 Status
0	= no strobe	0	= no strobe
1	= strobe	1	= strobe

Digital IRQ Status

0 = no digital interrupt

1 = digital interrupt

Digital IRQ Mode				Multi-Function
00	= Disabled			Register Select
01	= strobe Mode	Port 1 Direction		00	= clear mode
10	= event mode	0	= input	01	= port 0 direction
11	= match mode	1	= output	10	= mask register
				11	= compare register

Table 48 DIO-Control I/O Address 453h—Write Access

D7 D6 D5 D4 D3 D2 D1 D0

Reserved	Digital IRQ Mode				Multi-Function
	00	= Disabled			Register Select
	01	= strobe Mode	Port 1 Direction		00	= clear mode
	10	= event mode	0	= input	01	= port 0 direction
	11	= match mode	1	= output	10	= mask register
					11	= compare register

read/write

0 in, 1 out

0 no mask, 1 mask

read/write

Table 49 Multi-Function at Address 452h1

00 clear	X	X	X	X	X	X	X	X
01 Port 0 direction	I/O	I/O	I/O	I/O	I/O	I/O	I/O	I/O
10 DIO mask	M7	M6	M5	M4	M3	M2	M1	M0
11 compare	C7	C6	C5	C4	C3	C2	C1	C0

1. Contents based on bits D0 and D1 of DIO-Control.

Clear Register:

A read to this register Clears the IRQs and a write to this register sets the DIO-Compare, DIO- Mask, DIO-Control, Port 1, and Port 0 to zeros. A write to this register is used to clear the board.

Port 0 Direction Register:

Writing a zero to a bit in this register makes the corresponding pin of the aDIO connector an input. Writing a one to a bit in this register makes the corresponding pin of the aDIO connector an output.

Mask Register:

Writing a zero to a bit in this register will not mask off the corresponding bit in the DIO-Compare register. Writing a one to a bit in this register masks off the corresponding bit in the DIO-Compare register. When all bits are masked off the aDIOs comparator is disabled. This condition means Event and Match mode will not generate an interrupt. This register is used by Event and Match modes.

Compare Register:

A Read/Write register used for Match Mode. Bit values in this register that are not masked off are compared against the value on Port 0. A Match or Event causes bit 6 of DIO-Control to be set and if the aDIO is in Advanced interrupt mode, the Match or Event causes an interrupt.

BDM-610000049 Rev G Chapter 4: Using the cpuModule 63