wouter van ooijen wrote:

>> Now you say the best one can do is to take a printout of the map file
>> and enter the raw memory addresses manually when you want to send
>> something to the device? I'm almost certain that you would do better.
> 
> No, I said the operator has to specify *something*. A name is an
> instance of something. 

I'm not sure you read the article I was referring to. Here's an excerpt:

"When the identical and correct HGA parameters were uploaded to the
spacecraft, the operations team incorrectly specified the location for the
new parameter in the computer's memory.  Because the wrong memory location
was specified, the new parameter was written over the end of one and the
beginning of a second parameter being stored in onboard memory, corrupting
both parameters."

An upload software that doesn't have safeguards against this is a major
problem IMO.

> If the default ground operator interface used hex addresses instead of
> names I would consider that an error, but probably a design error or
> more probably a specification error, not a software error. 

So? It's still a major problem -- as this event showed.

> And note: that's ground software, not on-board software.

This is exactly my point.


>> I would never (well, I think... "never say never" :) deliver a device to
>> a user (and may it be a space device operator) that requires entering
>> raw addresses for changing parameters. 
> 
> For the space stuff I worked for such an interface was mandatory (a
> name-based interface was build on top of it, but the address-based
> interface was required to be available). So if you would not deliver it,
> your software would not fly (or rather: you would not be on the project
> at all).

Wouter... please read my stuff :)  If there was a name-based interface on
top of the raw address interface, that's exactly what I was suggesting (the
operators of your interface were not /required/ to use the address-based
interface) -- and what these guys obviously not had.


>> Such a space device should have the budget for a decent software for
>> parameter upload -- in the end, as can be seen, it's cheaper to have it
>> than not :)
> 
> That seems plausible, but did you realy try to do the math? Compare the
> extra cost (to make it conform to whatever you see fit) for *all*
> spacecraft, including the ones that never get launched, and then compare
> it to the cost you save (you still won't catch all errrors!). I am not
> saying you are not right, but I would not be convinced either way before
> someone put the calculation in front of me.

I have to admit that I never sent a device into space. But I sent devices
to factory floors, on the streets, and elsewhere -- and none of them
required a user to change configuration parameters using raw address
tables. From my experience, this would be a support nightmare. (And at
least if consumers were involved, could probably easily cause legal
problems, too.) So, yes, so far both me and my clients have come to the
conclusion that the expense for a human-readable interface that does not
allow the user to write to arbitrary addresses is worth the expense. (This
expense is not that big, either. It's rather straightforward to build this
on top of the raw address interface.)

Gerhard

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