16 May
2010
16 May
'10
6:43 a.m.
I querry all the sages out there for your
recommendations for a romulator and burner set of tools.
I know this isn't what you are looking for, but I thought I'd mention it because
it's
related and some of the guys on the list may find it "interesting".
One of the things I dug up and posted to my "DOS widgets" page in the past
couple of months is
"QDRE" (Quick and Dirty Rom Emulator). This is an ultra-cheap ROM emulator that
can be built
with only 5 chips. I created it years ago as a way for guys to get debug monitors and
other
diagnostics into various systems that I was helping them with remotely.
It consists of a socket with some counters attached to the PC parallel port, and moving a
module containing either a Dallas type NVRAM chip, or a powered RAM on an umbilical cable
(I didn't say it was a "clean" design - just ultra cheap). It does work!
While I'm on the embedded topic, has anyone herd
of this trick, their calling a 'glitching
environment', wherein the fuse protected ROM of a CPU is made available, by bouncing
the supply pin
under DAC control and monitoring the bus?
From what I understand, it puts the processor into an indeterminate state occasionally,
and allows
you to access the bus of a protected ROM in the CPU.
There are microcontrollers with "a security bit" and "secure
microcontrollers" - they are not the
same thing!
I recall guys filling the external address space of "protected" 8051s with NOPs
ending at a routine
to read out the internal memory and hitting the power rails until it glitched and jumped
outside
the internal memory...
Dave
--
dave09 (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Classic Computers: http://www.classiccmp.org/dunfield/