MPE/iX System Utilities Reference Manual (32650-90908)

Chapter 25
STANDARDS
The initial system loader
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The LIF volume label allows easy identification of media type and gives the location of the directory. The
format of the LIF volume label follows:
The directory contains all of the information necessary to find files. It is a linear list of 32-byte directory
entries, one for each LIF file on the media. The maximum number of entries in the directory is fixed at the
time of initialization. A logical end of directory mark is defined to be a file type of -1 and is written only if the
directory is not filled. The physical end of directory is determined by adding the start of directory and length
of directory fields from the volume lable. Directory entries must be stored so that they are in strictly
increasing starting addresses on sequential media. Directory entries are undefined after the logical end of
directory, so when a file is appended to the directory, the following directory entry’s file type must be set to -1
to make it the logical end of the directory.
LIF addressing is in blocks of 256 bytes, and system addresses are 2K-bytes-aligned.
Table 25-6 LIF volume label format
BYTE CONTENTS
0-1 LIF identifier
2-7 Volume label (0-6 ASCII characters)
8-11 Directory start address (in blocks)
12-13 Octal 10000
14-15 Set to 0 (dummy)
16-19 Length of directory (fixed at initialization)
20-21 Set to 0
22-23 Set to 0
24-41 Set to 0 (level 1 extension)
42-239 Set to 0 (reserved for extensions and future use)
240-243 Byte address of IPL on media
244-247 IPL length (in bytes)
248-251 Offset in IPL of entry
252-253 Set to 0
254-255 Set to 0 (reserved by system 250)