Technical data

System Dump Analyzer
EXAMINE
To examine a range of locations, you can designate starting and ending locations
separated by a colon. For example:
SDA> EXAMINE G40:G200
Alternatively, you can specify a location and a length, in bytes, separated by a
semicolon. For example:
SDA> EXAMINE G400;16
When used to display the contents of a range of locations, the EXAMINE
command displays six columns of information:
• Each of the first four columns represents a longword of memory, the contents
of which are displayed in hexadecimal format.
• The fifth column lists the ASCII value of each byte in each longword displayed
in the previous four columns.
• The sixth column contains the address of the first, or rightmost, longword
in each line. This address is also the address of the first, or leftmost,
character in the ASCII representation of the longwords. Thus, you read
the hexadecimal dump display from right to left, and the ASCII display from
left to right.
If a series of virtual addresses does not exist in physical memory, SDA displays a
message specifying the range of addresses that were not translated. For example:
SDA> EXAMINE 100:220
Virtual locations 00000100 through 000001FF are not in physical memory
0130011A 0120011B 0130011E 0110011F ......0... ...0. 00000200
01200107 02300510 04310216 04210218 ..!...1...0... . 00000210
01100103 01100104 01200105 01200106 .. ... ......... 00000220
Addresses 100
16
through 1FF
16
do not exist in memory, as the message indicates.
SDA displays the contents of those addresses that do exist (200
16
through 220
16
).
If a range of virtual locations contains only zeros, SDA displays this message:
Zeros suppressed from ’loc1’ to ’loc2’
Note that if you make a mistake specifying a virtual address for the EXAMINE
command and you are examining global page table entries, your system
may crash with a bugcheck. This occurs rarely and only when you use
ANALYZE/SYSTEM.
Decoding Locations
You can translate the contents of memory locations into MACRO instruction
format by using the /INSTRUCTION qualifier. This qualifier causes SDA
to display the location in symbolic notation (if possible) and its contents in
instruction format. The operands of decoded instructions are also displayed in
symbolic notation.
If the specified range of locations does not begin on an instruction boundary, SDA
skips bytes until it locates the next valid instruction and issues the following
message:
%SDA-W-INSKIPPED, unreasonable instruction stream - n bytes skipped
In this message, n represents the number of bytes that SDA could not translate.
SDA–55