AMD Am79C930 - Manual (Page 68)

AMD P R E L I M I N A R Y
68 Am79C930
ISA Plug and Play Register Set — The Am79C930 de-
vice fully supports the ISA Plug and Play specification,
revision 1.0a.
The Am79C930 device supports the Plug and Play
Auto-configuration scheme. The Plug and Play
ADDRESS Auto-configuration Port, WRITE_DATA
Auto-configuration Port, and READ_DATA Auto-con-
figuration Port are all supported and are mapped into
ISA I/O space as follows:
Am79C930 Device ISA Plug And Play Mode Supported Auto-Configuration Ports
Port Name ISA (IEEE P996) I/O Address Access
ADDRESS 0279h Write only
WRITE_DATA 0A79h Write only
READ_DATA 0203h – 03FFh (relocatable) Read only
The location of the READ_DATA Auto-configuration
port is only fixed within the range 0203h–03FFh. The
exact location is determined by a write to the appropriate
Plug and Play Auto-configuration port (Set
READ_DATA Auto-configuration port).
The WRITE_DATA port and the READ_DATA port are
not active until the Initiation Key has been sent to the
Am79C930 device through the ADDRESS port. This be-
havior conforms to the requirements of the Plug and
Play specification.
The Am79C930 device implements the four Plug and
Play configuration states: “Wait for Key,” “Sleep,”
Isolation,” and “Config.”
All Plug and Play ports are 8 bits in width.
To fully support the Plug and Play mechanism, the fol-
lowing additional register locations are defined within
the Am79C930 device. Except for the Resource Data
register, these registers are physically located within the
BIU and are accessed indirectly, through setting the
Plug and Play Port Address in the Plug and Play
ADDRESS port (location I/O 0279h) and then by ac-
cessing either the WRITE_DATA port or the
READ_DATA port. The 80188 embedded core does not
have access to the registers in the following table.