System Startup, Configuration, and Shutdown Reference Manual (32650-90892)

50 Chapter3
System Startup Functions
Initial System Loader (ISL)
Initial System Loader (ISL)
On tape boots, the ISL is loaded directly by the processor-dependent code (PDC). ISL reads
the logical interchange format (LIF) directory from tape and uses this directory to find
other files on the tape.
On disk boots, the PDC and IODC boot the utility MMSAVE, which in turn boots the ISL.
PDC and IODC read the first record or sector of the boot device, which is the LIF label. The
LIF label contains a pointer to the LIF directory which contains a pointer to the MMSAVE
boot image. PDC reads and launches MMSAVE. MMSAVE writes a 16-megabyte, (32 megabyte
for 99x system, 64 MB for N-Class and A-Class systems) section of main memory to the
DUMPAREA file, whose address is found in the LIF directory. This allows memory space for
the ISL and DUMP utilities to be loaded. MMSAVE boots ISL, which then uses the LIF label to
find the LIF directory. As a last step, ISL uses the directory to find other files it needs.
The system displays messages indicating the completion of the booting and loading
routines as they occur.
Using Initial System Loader (ISL) Commands
ISL commands change or display boot path information and ISL utility names. Table 3-1.
lists commands that do not execute a utility function. ISL utilities and options are
described later in this chapter.
Table 3-1. ISL Commands
Command Meaning
HELP Help Facility
LS List ISL utilities
AUTOBOOT Set or clear autoboot flag in stable storage
AUTOSEARCH Set or clear autosearch flag in stable storage
PRIMPATH Modify primary boot path in stable storage
ALTPATH Modify alternate boot path in stable storage
CONSPATH Modify system console path in stable storage
DISPLAY Display boot and console paths in stable storage
LSAUTOFL List contents of autoboot file
FASTSIZE Sets or displays FASTSIZE
800SUPPORT Boots the s800 Support Kernel from the boot device
700SUPPORT Boot the s700 Support Kernel from the boot device
READNVM Displays contents of one word of NVM
READSS Displays contents of one word of stable storage