A.1. Plug and Play Card Control Registers

Table A-1. Plug and Play Standard Registers

Name	Address Port Value	Definition
Set RD_DATA Port	0x00	Writing to this location modifies the address of the port used for reading from the Plug and Play ISA cards. Bits[7:0] become I/O read port address bits[9:2]. Reads from this register are ignored.
Serial Isolation	0x01	A read to this register causes a Plug and Play cards in the Isolation state to compare one bit of the boards ID. This process is fully described above. This register is read only.
Config Control	0x02	Bit[2] - Reset CSN to 0 Bit [1] - Return to the Wait for Key state Bit[0] - Reset all logical devices and restore configuration registers to their power-up values. A write to bit[0] of this register performs a reset function on all logical devices. This resets the contents of configuration registers to their default state. All card's logical devices enter their default state and the CSN is preserved. A write to bit[1] of this register causes all cards to enter the Wait for Key state but all CSNs are preserved and logical devices are not affected. A write to bit[2] of this register causes all cards to reset their CSN to zero . This register is write-only. The values are not sticky, that is, hardware will automatically clear them and there is no need for software to clear the bits.

Wake[CSN]	0x03	A write to this port will cause all cards that have a CSN that matches the write data[7:0] to go from the Sleep state to the either the Isolation state if the write data for this command is zero or the Config state if the write data is not zero. Additionally, the pointer to the byte-serial device is reset. This register is write-only.
Resource Data	0x04	A read from this address reads the next byte of resource information. The Status register must be polled until bit[0] is set before this register may be read. This register is read only.
Status	0x05	Bit[0] when set indicates it is okay to read the next data byte from the Resource Data register. This register is read-only.
Card Select Number	0x06	A write to this port sets a card's CSN. The CSN is a value uniquely assigned to each ISA card after the serial identification process so that each card may be individually selected during a Wake[CSN] command. This register is read/write.
Logical Device Number	0x07	Selects the current logical device. All reads and writes of memory, I/O, interrupt and DMA configuration information access the registers of the logical device written here. In addition, the I/O Range Check and Activate commands operate only on the selected logical device. This register is read/write. If a card has only 1 logical device, this location should be a read-only value of 0x00.
Card Level Reserved	0x08 - 0x1F	Reserved for future use
Card Level, Vendor Defined	0x20 - 0x2F	Vendor defined