Technical data

System Dump Analyzer
FORMAT
Certain data structures do not contain a block type at offset 0A
16
. If this byte
contains information other than a block type—or the byte does not contain a valid
block type—SDA displays this message:
%SDA-E-INVBLKTYP, invalid block type in specified block
To format such a block, you must reissue the FORMAT command, using the
/TYPE qualifier to designate a block-type.
The FORMAT command produces a 3-column display:
• The first column shows the virtual address of each item within the block.
• The second column lists each symbolic name associated with a location within
the block.
• The third column shows the contents of each item in hexadecimal format.
Example
SDA> READ SYS$SYSTEM:SYSDEF.STB
SDA> FORMAT 800B81F0
800B81F0 UCB$L_FQFL 80000F10
UCB$L_RQFL
UCB$W_MB_SEED
UCB$W_UNIT_SEED
800B81F4 UCB$L_FQBL 800026A8
UCB$L_RQBL
800B81F8 UCB$W_SIZE 00E0
800B81FA UCB$B_TYPE 10
800B81FB UCB$B_FLCK 07
800B81FC UCB$L_ASTQFL 800F80E0
UCB$L_FPC
UCB$T_PARTNER
800B8200 UCB$L_ASTQBL 8002CF80
UCB$L_FR3
800B8204 UCB$L_FIRST 8002CA00
UCB$L_FR4
UCB$W_MSGMAX
UCB$W_MSGCNT
.
.
.
From SYS$SYSTEM:SYSDEF.STB, the READ command loads into SDA’s symbol
table the symbols needed for formatting system data structures. The FORMAT
command displays the data structure that begins at 800B81F0
16
, a unit control
block (UCB). If a field has more than one symbolic name, all such names are
displayed. Thus, the field that starts at 800B8204
16
has three designations:
UCB$L_FIRST and UCB$L_FR4, alternative names for the longword; and the
two subfields, UCB$W_MSGMAX and UCB$W_MSGCNT.
The contents of each field appear to the right of the symbolic name of the field.
Thus, the contents of UCB$L_FIRST are 8002CA00
16
.
SDA–59