27 Jan
2006
27 Jan
'06
9:30 p.m.
what about asics, fplds, fpgar, vlsis (the latter
being of most interest to me), etc. etc. etc. Can
those be readily reverse engineered. Say you had a
*bad* vlsi, and a block diagram of its innards. Could
the *details* be worked out, and would it be feasible
to reproduce it as an fpga?
--- cctech-bounces at classiccmp.org
<ard at p850ug1.demon.co.uk> wrote:
front door.
> (and contents) when it was removed from the
circuit. Or else redisign and
> use a PAL or some form or programmable logic that
has a security fuse to
prevent it
from being read.
Oh come on. PALs are about as secure as a cardboard
If you're going to allow unpackaging the chip, then
remember that PAls
used the old fusible-link technology. And those
links will be in the top
metalisation layer. You could see which ones were
intact and which were
blown with a microscope. And I guess if you could
open up a new example
of the same make and type of PAL without damaging
it, you could blow the
links one at a time and keep on looking at the chip
to work out which was
which.
But why go to all that trouble? Even if the security
fuse is blown, it's
possible to reverse-engineer a PAL using well-known
techniques of
applying various inputs and looking at the outputs.
With a PAL there is
no way to have a hidden variable. Any flip-flop in
the chip (wether part
of thr 'R' of a registered PAL, or made from
the
AND/OR matrix) will
appear on one of the pins (this is not true of GALs,
unfortunately). So
with a PAL it's relatively easy to work out
what's
going on.
-tony
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28 Jan
28 Jan
7:17 a.m.
Chris M wrote:
what about asics, fplds, fpgar, vlsis (the latter
being of most interest to me), etc. etc. etc. Can
those be readily reverse engineered. Say you had a
*bad* vlsi, and a block diagram of its innards. Could
the *details* be worked out, and would it be feasible
to reproduce it as an fpga?
It is possible.
If you have access to the right equipment, unlimited time and busloads
of money.
If you meant to say : I want to repair this machine which has a broken
unobtainable vlsi chip, then forget it . A oneoff copy of a vlsi chip in
a FPGA is just plain too much work.
The easiest solution is to recreate the design from scratch, using VHDL
or Verilog. Understanding the machine that the chip was operating in is
much more important than shaving bits of a defective chip trying to
obtain a schematic.
Jos Dreesen
9:27 a.m.
New subject: Fixing CoCo3's (was: grinding down chips...
Rumor has it that Jos Dreesen / Marian Capel may have mentioned these words:
If you meant to say : I want to repair this machine
which has a broken
unobtainable vlsi chip, then forget it . A oneoff copy of a vlsi chip
in a FPGA is just plain too much work.
With all due respect, *please* keep that attitude away from the Tandy Color
Computer List! :-O
There are people doing *exactly that* to try to keep our beloved CoCo3's
running once the GIME chip start giving up the magic smoke in quantity.
In the immortal words of Bartles & Jaymes: Thank you for your support.
;-)
Laterz,
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger -- SysAdmin, Iceberg Computers
zmerch at 30below.com
Hi! I am a .signature virus. Copy me into your .signature to join in!
12:04 p.m.
New subject: Fixing CoCo3's
Roger Merchberger wrote:
Rumor has it that Jos Dreesen / Marian Capel may have
mentioned these
words:
By redesigning a functional equivalent, or by deprocessing a failed chip?
The first is perfectly OK and feasible, the second one is a major work.
Things are simpler for a 20 years old design, but still....
Jos
If you meant to say : I want to repair this
machine which has a broken
unobtainable vlsi chip, then forget it . A oneoff copy of a vlsi chip
in a FPGA is just plain too much work.
With all due respect, *please* keep that attitude away from the Tandy
Color Computer List! :-O
There are people doing *exactly that* to try to keep our beloved CoCo3's
running once the GIME chip start giving up the magic smoke in quantity.
30 Jan
30 Jan
12:10 p.m.
New subject: Fixing CoCo3's
Rumor has it that Jos Dreesen may have mentioned these words:
Roger Merchberger wrote:
Yes.
;-)
There's rumors of a TTL prototype board out there, but if not, a chip may
well need to be depackaged/deprocessed and probed manually to figure how
just how the heck the thing works.
To my knowledge, there's no surviving VHDL or somesuch to actually tell us
how the durned thing works - it's a little black box.
Laterz,
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger | "Profile, don't speculate."
SysAdmin, Iceberg Computers | Daniel J. Bernstein
zmerch at 30below.com |
Rumor has it that Jos Dreesen / Marian Capel may
have mentioned these words:
By
redesigning a functional equivalent, or by deprocessing a failed chip? If you meant to say : I want to repair this
machine which has a broken
unobtainable vlsi chip, then forget it . A oneoff copy of a vlsi chip
in a FPGA is just plain too much work.
With all due respect, *please* keep that
attitude away from the Tandy
Color Computer List! :-O
There are people doing *exactly that* to try to keep our beloved CoCo3's
running once the GIME chip start giving up the magic smoke in quantity.
6820
days inactive
6822
days old
4 comments
4 participants
participants (4)
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chrism3667＠yahoo.com -
jos.dreesen＠bluewin.ch -
jos.mar＠bluewin.ch -
zmerch＠30below.com