BIOSSIG is a BIOS ROM Signature Identification Database/Program. BIOSSIG
is a "Work In Progress". It is hoped that the program, written in Borland's
Turbo Prolog 2.0, can someday be made to appear "artifically intelligent" in
such a manner as to accurately determine the Signature of a BIOS ROM not in its
current database. In its current implementation BIOSSIG simply matches the
contents of its database with the contents of your BIOS. One option looks
for an exact match and reports its results very quickly. Another option
only looks at BIOSs that have the same IBM Model Id Byte as your BIOS. This
option takes longer, but allows you to then scan the signatures of BIOS's with
signatures similar to the one in your PC. You may also print a formatted
report describing the signatures of all of the BIOSs known to us today.

BIOSSIG starts in Color, without suppressing CGA "Snow". It's Color scheme may
be modified from the Optional Customization menu. Some Monochrome adapters
do not display the default BIOSSIG color scheme (others do). If your monochrome
screen blanks and all disk activity stops without any messages appearing, then
monochrome may be selected on start up by including "mono" on the command line.

Some Color Graphics Adapters display "snow" on your color screen if they
are accessed via direct writes to video memory. If you do see "snow", try
setting Snow Suppression Required. Using this setting slows down the display
slightly to prevent generating the snow. No Snow Suppression will restore
BIOSSIG to its fastest display speed. CGA Snow suppression may be selected on
start up by including "snow" on the command line or by exercizing the optional
customization menu.

BIOSSIG prints 132 Columns of information per page. If you select 6 Lines/Inch,
BIOSSIG will print 5 Signatures/Page. If you select 8 Lines/Inch, BIOSSIG
will print 7 Signatures/Page.

To give some indication that the program is working while it scans its database
(Now at 390+ entries and growing) BIOSSIG displays the file name of each BIOS
Signature and a percentage of match between your BIOS and each database entry.

Sample BIOS Signature Screen(s)

BIOS Signature 3.2
Model Id Byte at FFFFE matches 100%
FC Overall Match: 100% CRC
Your BIOS Signature is in our F0000
Date at FFFF5 matches 100% Database as shown below, but FFFFF
08/12/87 its CRC does not match. Please C2F0
submit this BIOS and its Info. C2F1
Part Number at FE000 matches 100%
NCR'S VERSION IBM CORP. AT ROM

Compatibility at FE00E matches 100%
IBM

Copyright at FE01E matches 100%
COPR. NCR CORP. 1985,1987COPR. COMPUTER DEVICES INC. 1982

OEM Revision at FFFEA matches 100%
NCR4.5


PC: Honeywell AP | NCR P8 Test with Bad CR BIOS: NCR 4.5
Source: Mike Focke
Date: 5 July 1988 BIOS Signature File: NCR4-5x

Esc to return to Main Menu, F10 to attempt another Exact match

BIOS Signature 3.2
Model Id Byte at FFFFE matches 100%
FC Overall Match: 100% CRC
F0000
Date at FFFF5 matches 100% Your BIOS Signature is in our FFFFF
08/12/87 Database as shown below. Please C2F0
inform us if you disagree.
Part Number at FE000 matches 100%
NCR'S VERSION IBM CORP. AT ROM

Compatibility at FE00E matches 100%
IBM

Copyright at FE01E matches 100%
COPR. NCR CORP. 1985,1987COPR. COMPUTER DEVICES INC. 1982

OEM Revision at FFFEA matches 100%
NCR4.5


PC: Honeywell AP | NCR P8 BIOS: NCR 4.5
Source: Mike Focke
Date: 5 July 1988 BIOS Signature File: NCR4-5

Esc to return to Main Menu, F10 to attempt another Exact match

BIOS Signature 3.2
Model Id Byte at FFFFE matches 100%
FC Overall Match: 98% CRC
Your BIOS does not match the F0000
Date at FFFF5 matches 62% currently displayed database FFFFF
08/12/87 entry. The second line of any C2F0
05/02/88 pair comes from the database. A916
Part Number at FE000 matches 100%
NCR'S VERSION IBM CORP. AT ROM

Compatibility at FE00E matches 100%
IBM

Copyright at FE01E matches 100%
COPR. NCR CORP. 1985,1987COPR. COMPUTER DEVICES INC. 1982

OEM Revision at FFFEA matches 83%
NCR4.5
NCR4.6

PC: Honeywell AP | NCR P8 BIOS: NCR 4.6
Source: Cathy Cockrum Brower
Date: 3 November 1988 BIOS Signature File: NCR4-6

Press F10 for next worst match, Press Esc to Quit

For the purposes of the BIOS Signature Project a BIOS ROM Signature consists of
the following six pieces of information:

Model Id Byte
Date
Part Number
Compatibility
Copyright
OEM Revision


Model Id Byte:

IBM puts a coded byte in BIOS ROM memory location FFFFE. PC Magazine
June 28, 1988 published a list of the IBM Model Id Bytes as follows:

FF - IBM PC
FE - IBM PC-XT
FD - IBM PCjr
FC - IBM PC AT
FB - IBM PC-XT(rev 1)
FA - IBM PS/2 Model 30
F9 - IBM PC Convertible
F8 - IBM PS/2 Model 80

Date:

IBM puts the Date the BIOS ROM was issued in BIOS ROM memory location FFFF5.

Part Number:

IBM put the Part Number of the BIOS ROM in the early BIOS ROM chips in BIOS
ROM memory location FE000. The BIOS Signature Database uses the Part Number
if appropriate or other identifying text if not an IBM BIOS ROM.

Compatibility:

Nominally all of the BIOS ROMs of interest are IBM compatible. The story is
that when the first IBM PC was introduced some programs looked for "IBM" in
the BIOS ROM. If "IBM" was not there the programs (a) didn't run or
(b) trashed something. This is the theory behind looking for "IBM" in BIOS
ROM memory. Not all modern (nominally IBM compatible) ROMs contain the IBM
trademark. Those BIOSs that do contain the "IBM" normally put it where IBM
puts its copyright notice.

Copyright:

IBM puts a Copyright notice for the BIOS ROM in BIOS ROM memory location FE008.
Most other manufacturers also put copyright notices in their own BIOS Roms.
There is some discussion as to what it takes to be a legal copyright notice.
Minimally there should be the Copyright symbol, a "C" within a circle. Most
BIOS ROMs approximate this symbol with a (C) or (c) using matched parentheses
to enclose the "C". The word Copyright should be spelled out if the symbol is
not present. The Year for which the copyright is claimed is required. The
name of the entity claiming the copyright is the last required information.

OEM Revision:

Some Original Equipment Manufacturers (OEMs) have added information to uniquely
identify a BIOS ROM. This is an OEM Revision (Number). When an OEM BIOS ROM
initializes the PC (boots), it normally displays its revision on the Console.

Address:

This is the BIOS ROM memory address (shown in Hexadecimal Notation) where the
information may be found in matching BIOS ROMs.

Match:

This is the Percentage Match between Your BIOS ROM and the BIOS ROM from
the BIOS Signature Database. It is computed by recursively matching the
longest common substrings between the contents of the database and the
corresponding areas of your BIOS ROM memory. An Exact Match yields 100%.
If 10 characters out of 20 are the same, even if they are not in the exact
order of the database, then the match is 50%.

The Overall match is computed by arbitrarily assigning a length of one to the
Model Id Byte and the Date. For each item in the signature the Match is
multiplied by the length in characters, the sum of these products is divided
by the total length giving the Overall Match as a percentage of the total
characters.

PC:

The Brand Name of the Manufacturer mentioning any identifying characteristics.

BIOS:

The Name of the BIOS Manufacturer (from the ASCII Copyright Statement if
available).

Source:

The Name of the Person who first supplied the BIOS Signature Project with the
required information.

Date:

The Date the information was acquired.

BIOS Signature File:

The File containing the contents of that BIOS ROM on our computer.
Also used as a unique identifier.

CRC:

To differentiate between multiple BIOSs with the same ASCII BIOS Signature as
defined above, version 3.1c implemented a Cyclic Redundancy Check of your BIOS
ROM. A CRC is a mathematical calculation which is used in communications to
detect errors in a block of data. The operation is performed on a data block,
the block and CRC are transmitted, the receiver independently computes the
CRC of the received block and compares it to the CRC computed by the sender.
If the two CRCs are the same it is assumed that the block has been transmitted
and received correctly. According to W. David Schwaderer's CRC Calculation
article in the April 1985 issue of PC Tech Journal, "Using these polynomials
allows detection of all errors involving 16 bits or less and about 99.95
percent of errors involving more than 16 bits."

The two 5 digit hex addresses are the address of the first and last bytes of
the block of information upon which the CRC computation is calculated. The
next 4 digits = the 16-bit CRC of your BIOS. If the database contains a
different CRC it is displayed below yours. If the ASCII BIOS Signature of
your BIOS ROM is an exact ( 100 percent) match, but the CRCs are different,
your BIOS Manufacturer has issued 2 ROMS with identical signatures but
different code. There are, for example, 2 Zenith entries in the database
with the same signature but different CRCs. There were only 5 bytes different
between the 2 BIOS. One BIOS came from a Z-183 the other from a Z-184.

The Future:

Even after examining 390+ BIOSs, we are still learning how to recognize those
of a particular brand. We had intended that, once we feel we knew enough
about how Phoenix, Award, AMI, Compaq and IBM typically store the signature
information, then we hoped to be able to include logic to recognize the
signatures of BIOSs we hadn't yet seen. We have largely abandoned that
notion as the number of BIOSs became clear and as other duties kept us busy.

BIOSTREE

BIOSTREE displays a family tree of BIOSs.

Legal Concerns:

Both Rick and I work for a computer manufacturer who will buy us any BIOS
we want. Our intent is to add to the litterature about BIOS signatures and
the only way to do this is to examine the code to find the signatures.
We don't use the BIOS you send us for any other purpose. Please don't ask
us to send you the latest BIOS. We won't! See the file sources.txt for places
that sell BIOS.

Special thanks to Bob Falk for providing BIOSXLAT.EXE, a program which
provides a formatted file with readable information from our data base.