old processor -- 8085

"g. beat " @spam protected wrote in message
. ..
With the availability of the Intel Pentium processor (space rated) -- I am
curious what space application would warrant such a "new processor" --
used for a sub-system?

I don't know the new chip, but I would guess that one advantage might be
lower power consumption than later chips that use way more circuitry than
required by many applications.


Jim McCauley

a écrit dans le message de news:
...
: duplicate the
CPU pipeline multiple times and have a voting system between pipeline
stages so that any single failure won't take down the whole system...


That's one solution used to reduce probability of upsets ( not only for
radiation, BTW )..... provided your voting system itself is not susceptible
to radiation-induced failure ( which is a design mistake I saw more than
once ); in which case, it could - possibly - reduce the probability but not
as much as first thought. -

Also this solution has the disadvantage of requiring many time the computing
power and so costs in weight and electrical power.

In ATV, for exemple, the central processing unit is called a Fault tolerent
computer and has 3 processing units going in //, with a vote at the output.
That's also used in a lot of component, dowm to FPGA design ( TMR ).

In article ,
frédéric haessig wrote:
: duplicate the CPU pipeline
multiple times and have a voting system between pipeline stages...

That's one solution used to reduce probability of upsets ( not only for
radiation, BTW )..... provided your voting system itself is not susceptible
to radiation-induced failure ( which is a design mistake I saw more than
once )...

Another "provided" is "provided you have some way to test the replicated
pipelines independently, and without the test circuitry adding radiation
vulnerabilities too". (I understand that was the really tricky part of
Actel's rad-hard FPGAs, which have voted triple redundancy in every cell
and hence give transparent voting-out of single-bit upsets.)
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

rk wrote:
On Mon, 24 Jul 2006 23:50:23 GMT, (Henry Spencer) wrote:

In article ,
frédéric haessig wrote:
: duplicate the CPU pipeline
multiple times and have a voting system between pipeline stages...

That's one solution used to reduce probability of upsets ( not only for
radiation, BTW )..... provided your voting system itself is not susceptible
to radiation-induced failure ( which is a design mistake I saw more than
once )...

I was talking to a guy from Intel last week, and he said that as the
feature size on processors falls below 45nm the soft error rate is
becoming significant across the system. "We're not going to need
rad-hard latch registers yet, but..." I thought he was joking, but he
wasn't. Standard commercial processor designs are going to need a
significant (as in 10 percent) amount of real estate given over to
detecting and correcting errors, and probably quite soon.

rupert



--
rk, Just an OldEngineer
"The number of people having any connection with the project must be
restricted in an almost vicious manner. Use a small number of good people."
-- Kelly Johnson in Skunk Works

"Rupert Goodwins" a écrit dans le message de news:
...

I was talking to a guy from Intel last week, and he said that as the
feature size on processors falls below 45nm the soft error rate is
becoming significant across the system. "We're not going to need
rad-hard latch registers yet, but..." I thought he was joking, but he
wasn't. Standard commercial processor designs are going to need a
significant (as in 10 percent) amount of real estate given over to
detecting and correcting errors, and probably quite soon.


Yes, the problem already occurs quite often in high altitude flying planes.
As design size go down, so will the altitude at which problems are
significants. Untill it reaches sea-level.

I wonder which of the possible tech solution will be chosen. If it's one
robust enough, we could once again fly commercial components in Space ( at
least from a radiation PoV )