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1993-03-08
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95 lines
FYI
(Note: The origin of this information may be internal or
external to Novell. Novell makes every effort within its means
to verify this information. However, the information provided in
this document is FOR YOUR INFORMATION only. Novell makes no
explicit or implied claims as to the validity of this
information.)
TITLE: USING SID TO DETECT THE LOCATION OF ROM'S IN
THE MEMORY MAP
DOCUMENT ID#: FYI-M-1116
DATE: 06JAN93
PRODUCT: DR DOS
PRODUCT VERSION: 6.0
SUPERSEDES: 13APR92
SYMPTOM: UNABLE TO DETERMINE WHY SOME AREAS IN RAM HAVE
BEEN EXCLUDED FROM USE
ISSUE/PROBLEM: After loading the EMM386.SYS memory management
driver, you may notice that the MEM /A display shows an area of
upper memory as excluded from use. After attempts to access the
excluded memory area have failed, you may suspect that some
memory addressed ROM chips are occupying that area.
SOLUTION: The SID utility can be used to check on these
excluded areas of memory. This can be done by loading SID and
searching the specific areas of memory for copyright information.
If a ROM is found, displaying that area in memory may help you
tell which piece of hardware is using that area in memory.
EXAMPLE: The following is an excerpt of a MEM /A display
that shows an area excluded at D7FF:0000 and a ROM chip at
D800:0000. The exclusion will precede the ROM chip itself to
protect the address of the ROM.
│ CF00:0000 │ -------- │ 9000h, 36,864 │ ---------- Upper RAM
├───────────┼──────────┼──────────────────┼──────────────────────
│ CF00:0000 │ DR DOS │ 8FF0h, 36,848 │ System
│ CFE3:15C0 │ DR DOS │ DE0h, 3,552 │ DR DOS BIOS code
│ D7FF:0000 │ EXCLUDED │ 2010h, 8,208 │ Upper system memory
├───────────┼──────────┼──────────────────┼──────────────────────
│ D800:0000 │ -------- │ 2000h, 8,192 │ ------------- ROM ---
│ DA00:0000 │ -------- │ 16000h, 90,112 │ ---------- Upper RAM
├───────────┼──────────┼──────────────────┼──────────────────────
│ DA00:0000 │ DR DOS │ 9450h, 37,968 │ System
│ D701:3000 │ DR DOS │ 9440h, 37,952 │ DR DOS kernel code
Load SID to investigate the memory area in question. SID
displays the # prompt. Use the SR command to look for all of the
possible variations of the copyright markings. For example, the
MEM display shows something at D800:0000, so use the command:
SRD800:0000,FFFF,"COPYRIGHT"
|_______|-> Change this number to investigate different
areas of memory.
"COPYRIGHT","Copyright","copyright","(C)",and "(c)" should cover
all of the bases. Notice that the search is case sensitive. If
SID finds some data in memory that matches the search parameters,
it will display the address of that data in SEGMENT:OFFSET
format. Make a note of any addresses that are displayed. Then
display the data at each of those locations using the D command.
The company name should provide some idea of the hardware
occupying that area of memory. Displayed below is what the
investigation of the above machine revealed:
[DR DOS] C:\>SID
--------------------------------------------------
*** Symbolic Instruction Debugger *** Release 3.2
Copyright (c) 1983,1984,1985,1988,1990,1991,
Inc. All Rights Reserved
--------------------------------------------------
( COMMENTS )
#SRD800:0,FFFF,"COPYRIGHT" ( Nothing found )
#SRD800:0,FFFF,"copyright" ( Nothing found )
#SRD800:0,FFFF,"Copyright"
D800:0056 ( BINGO !! )
#DD800:0056 ( Display that area )
D800:0056 43 67 68 74 20 28 43 29 20 31 39 Copyright (C) 19
D800:0066 38 42 54 72 61 6E 74 6F 72 20 53 89-90, Trantor S
D800:0076 79 73 2C 20 4C 74 64 2E 0D 0A 00 1A ystems, Ltd.....
D800:0086 00 07 73 01 CB 8D 36 34 00 E8 A6 04 ....9.s...64....
D800:0096 B8 C6 06 74 00 00 C6 06 75 00 00 C6 .@.....t....u...
#
The copyright is held by the company that made the card that
connects to the CDROM player in this particular machine. The
presence of the card is why this area of memory is excluded.
ADDITONAL REFERENCES: DR DOS 6.0 User Guide, Appendix D &
FYI-M-1114 & FYI-M-1115.