27 Sep
1999
27 Sep
'99
8:34 a.m.
Worse still, on say a Unix system, you can reboot the system from your own
boot floppy and bypass the security system.
Neil Morrison
email:morrison@t-iii.com
-----Original Message-----
From: ard(a)p850ug1.demon.co.uk [SMTP:ard@p850ug1.demon.co.uk]
Sent: Monday, September 27, 1999 12:58 PM
To: Discussion re-collecting of classic computers
Subject: Re: Ace
------------------
Mind you, if you've got that sort
of access, you could remove disk packs (or tapes) and read them on your
own machine.
------------------
27 Sep
27 Sep
8:38 a.m.
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9:37 a.m.
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28 Sep
28 Sep
6:18 a.m.
On Mon, Sep 27, 1999 at 10:37:10PM +0100, Tony Duell wrote:
Make a card with a BIOS extension ROM on it that
either boots a
floppy no matter what the NVRAM contains, or edits the NVRAM to
enable standard floppy boots. Drop that into your machine and go.
Why go to such extreme lengths to clear the NVRAM?
Hints: Leatherman[1]. CMOS battery. Jumper.
[1] Although I'm told the SwissTool is of better quality.
--
Brad Ackerman N1MNB "44% [of Americans] believe in strict Biblical
bsa3(a)cornell.edu creationism. Four million also believe that
PGP: 0x62D6B223 they have been abducted by aliens."
http://skaro.pair.com/ -- _The Economist_, 4 Sep 1999
8:49 a.m.
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10:24 a.m.
ard(a)p850ug1.demon.co.uk (Tony Duell) wrote:
Well, what if the NVRAM is one of those Dallas devices with the battery,
clock/NVRAM chip and crystal encapsulated in the same package. No easy
way to pull a jumper and clear those.
Hi
Most of the ones I've seen used in computers are the normal
NVRAM's that Dallas sells. These have no security bits or
special access codes. To a system, they look just like
comparable sized CMOS RAMs. They can even be plugged into
the same sockets.
Dwight
11:06 a.m.
Rumor has it that Dwight Elvey may have mentioned these words:
ard(a)p850ug1.demon.co.uk (Tony Duell) wrote:
Ah... depends on the Dallas device. The two main devices used on (older)
motherboards are the 12887 and the 12887A.
Anyone care to take a guess as to the difference?
The 12887A has a "erase" pin on the package, so even if there are no
jumpers on the motherboard to erase the CMOS, you can jumper that pin to
ground for a few seconds and Voila! Wiped settings.
The reason for the "A"? The 12887 had _no_ pin for erasure, and if you
forgot your CMOS password, or your CMOS got jumbled, you're SOL. (That's
Surely Outta Luck... ;-) Many of the cheaper motherboard manufacturers
soldered that package to the board, as well... meaning if you wanted to use
that motherboard, either desolder that chip, install a socket, then put in
a 12887A, or wait 10+ years for the battery to die. (even for that, the
board's close to useless... once you turn off the 'puter, it'll forget all
your CMOS settings.)
PDF's of those parts are available from Dallas's website, which IIRC is
http://www.dalsemi.com/
HTH,
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger --- sysadmin, Iceberg Computers
Recycling is good, right??? Ok, so I'll recycle an old .sig.
If at first you don't succeed, nuclear warhead
disarmament should *not* be your first career choice.
Well, what if the NVRAM is one of those Dallas devices with the battery,
clock/NVRAM chip and crystal encapsulated in the same package. No easy
way to pull a jumper and clear those.
Hi
Most of the ones I've seen used in computers are the normal
NVRAM's that Dallas sells. These have no security bits or
special access codes. To a system, they look just like
comparable sized CMOS RAMs. They can even be plugged into
the same sockets.
Dwight 
27 Sep
27 Sep
7:12 p.m.
Date: Tue, 28 Sep 1999 19:06:02 -0400
Reply-to: classiccmp(a)u.washington.edu
From: Roger Merchberger <zmerch(a)30below.com>
To: "Discussion re-collecting of classic computers"
<classiccmp(a)u.washington.edu>
Subject: Re: Ace & Security
Anyone care to take a guess as to the difference?
The 12887A has a "erase" pin on the package, so even if there are no
jumpers on the motherboard to erase the CMOS, you can jumper that pin to
ground for a few seconds and Voila! Wiped settings.
To clarify that, that shorting withing futher steps do NOTHING. The
usual practice is jumper it and toggle power for few seconds then
power down and pull aside that jumper.
a 12887A, or wait 10+ years for the battery to die.
(even for that, the
board's close to useless... once you turn off the 'puter, it'll forget all
your CMOS settings.)
12B887 is same thing too as 12887A far as I can tell.
PDF's of those parts are available from Dallas's website, which IIRC is
http://www.dalsemi.com/
HTH,
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger --- sysadmin, Iceberg Computers
Recycling is good, right??? Ok, so I'll recycle an old .sig.
If at first you don't succeed, nuclear warhead
disarmament should *not* be your first career choice.
Wizard
28 Sep
28 Sep
1:38 p.m.
New subject: Dallas RTC chips (was: Ace & Security)
Rumor has it that jpero(a)cgocable.net may have mentioned these words:
Survey Says: Bzzzt. Not the 12887A. Just jumpering the pin for a few
seconds is all it takes - no power cycles at all. You can clear the memory
when the motherboard is out of the case and hooked to nothing. [[o.k...
Make me get the PDFs...]]
Dangit... those PDFs almost drove me batty, until you get to the last page
of each... The pinout for both chips are exactly the same, with pin 21
being _RCLR_, or Active Low Ram Clear... but on the 12887 the last page
says this:
NOTE: PINS 2, 3, 16, 20, 21 AND 22 ARE MISSING BY DESIGN.
[[ the page held all caps - I'm not yelling, I'm quoting. ;-)]]
The 12887A chip says this on the last page:
NOTE: PINS 2, 3, 16, 20 AND 22 ARE MISSING BY DESIGN.
[[ the page held all caps - I'm not yelling, I'm quoting. ;-)]]
So, they gave the 12887 the ability to clear it's RAM, but they didn't
bother to put a darned pin there!!! Is that loopy, or what?
Anyone care to
take a guess as to the difference?
The 12887A has a "erase" pin on the package, so even if there are no
jumpers on the motherboard to erase the CMOS, you can jumper that pin to
ground for a few seconds and Voila! Wiped settings.
To clarify that, that shorting withing futher steps do NOTHING. The
usual practice is jumper it and toggle power for few seconds then
power down and pull aside that jumper. 12B887 is same thing too as 12887A far as I can tell.
Ah, maybe... I don't know about stuff newer than the A series, but while
downloading the PDFs, it seems theres a 12C887 available now. (BTW, there
is no PDF for a 12B887... maybe they're phased out already???)
Geezzzzz... a quick peek at that PDF shows that there is no _RCLR_ pin at
pin 21 anymore -- it shows No Connection. Boy doesn't that irritate me!!! :-(
Well, the PDF was listed as "Preliminary," so maybe they're still doing
revisions on the chip... Let's hope so.
Anywho, back to work...
"Merch"
--
Roger "Merch" Merchberger --- sysadmin, Iceberg Computers
Recycling is good, right??? Ok, so I'll recycle an old .sig.
If at first you don't succeed, nuclear warhead
disarmament should *not* be your first career choice.
29 Sep
29 Sep
5:55 a.m.
New subject: Dallas RTC chips (was: Ace & Security)
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9216
days inactive
9218
days old
9 comments
7 participants
participants (7)
-
ard＠p850ug1.demon.co.uk -
bsa3＠cornell.edu -
drd＠mv.mv.com -
elvey＠hal.com -
jpero＠cgocable.net -
morrison＠t-iii.com -
zmerch＠30below.com