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Reading Nonvolatile Memory (NVM)

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(Not applicable to N-Class and A-Class ) NVM stores system activity parameters, including a circular queue of the last six ISL utilities executed, which is useful as a diagnostic aid in the event of a system crash or failure.

NVM contains initialization information in a 92-byte block starting at decimal byte address 36. NVM stores this information as shown in Figure C-2 NVM Contents.

Figure C-2 NVM Contents

[NVM Contents]

To read an NVM location, enter the ISL READNVM command and enter the hexadecimal or decimal address. The output is always in hexadecimal. In the following examples, addresses are referred to in decimal notation and the output is in hexadecimal notation.

The last boot path, starting at byte address decimal 36, contains the status of the autoboot and autosearch flags during the boot sequence.

Address decimal 68 contains the ISL revision number in ASCII. 

  ISL> READNVM 68

    Address 68 contains 0x32363334   *** ISL Revision 2738 ***
The TIMESTAMP is in seconds since 1/1/70.Locations 76 through 123 contain the names of the utilities booted. They are placed into a circular queue. The pointer at location 124 (first two digits) is positioned to the last utility executed. The pointer ranges from 1-6 (decimal) or 01-06 (hexadecimal), indicating which utility (1-6 — top to bottom on Figure C-2 NVM Contents) was last executed. 

   ISL> READNVM 124

     Address 124 contains 0x030600AC

     (The last six digits vary)
The first two digits, 03, indicate that the pointer is positioned to the third utility name location (decimal address 92) in the queue.

Read location 92 to find the hexadecimal representation of the name: 

   ISL> READNVM 92

      Address 92 contains 0x53544152

      (53=S 54=T 41=A 52=R which spells out STAR)
Since each location is limited to four characters, additional characters are located in the next word: 

   ISL> READNVM 96

     Address 96 contains 0x54202020

     (54=T 20=Blank which adds the last T for start)
Table C-1 Codes for ISL Utility Names lists the ISL utility names and the hexadecimal representation for both uppercase and lowercase spellings.

Table C-1 Codes for ISL Utility Names

Utility

Uppercase

Lowercase
START 53 54 41 52 54 73 74 61 72 74
UPDATE 55 50 44 41 54 45 75 70 64 61 74 65
INSTALL49 4E 53 54 41 4C 4C69 6E 73 73 61 6C 6C
DUMP 44 55 4D 50

64 75 6D 70



Reading Stable Storage Contents

Appendix D Default Configurations Used by INSTALL and UPDATE