MPE/iX System Utilities Reference Manual (32650-90882)

216 Chapter25
STANDARDS
The initial system loader
NVM is an optional implementation, not required by the architecture. If NVM is
implemented, the PDC and boot reserved area of NVM is as follows:
LIF standard
The Hewlett-Packard Logical Interchange Format (LIF) provides a standard method for
locating IPL code on the boot device.
The method of locating IPL code on the boot device must be the same for all boot devices,
computer processors, and the operating systems, so that the PDC knows where to find it.
Having IPL at the very beginning of the device is ideal; however, some operating systems
require a volume label at the beginning of a disk. IPL also needs a method of locating its
modules (utilities) when they are needed.
The LIF standard addresses these issues, and provides a standard with utilities already in
existence. For further information on LIF format, refer to LIF Directory Organization and
Record Format for Data Interchange.
LIF requires a 256-byte volume label at the beginning of the media; thus, the
operating-system-specific volume label can be located at the beginning of the disk, offset by
256 bytes. The LIF volume label points to the location of the LIF directory, which then
points to the location of each of the files.
Compliance to LIF standard does not require complete implementation. The level of
compliance to the standard in the IPL code is the minimum implementation (volume
header and directory in ASCII code). The format of the files is the system object module
(SOM) format.
The LIF volume header, as well as an entry in the LIF directory, points to the IPL code.
Table 25-5. PDC and boot area for NVM
BYTE CONTENTS
0-1F Last boot-device path
20-23 Self-test status
24-27 Powerfail time stamp
28-2A Boot restart time stamp
2B-2F TOC restart time stamp
30-63 PDC and boot reserved