Ask if it's policy to enable the watchdog timer. The correct answer is "no".
If they say "yes" then you know that their code is dodgy, and/or their hardware is vulnerable and if the WDT is not going off occassionally, it probably will after the next modification.
Unless you absolutely, positively can't afford not to take a contract, anyone who comes up with this sort of pig-ignorant over generalisation from a limited knowledge base is someone you don't want to work for. The mere idea that this can be simplified to a yes or no question indicates the questioner's willingness to micro-manage a complex technical decision and proclaim edicts on subjects that are beyond his knowledge and understanding. No good can come from working with such an arrogant simpleton.
Watchdogs are not there to protect against dodgy code and/or unduly "vulnerable" hardware. They're there because, ultimately, *all* hardware is vulnerable. It's just a question of degree. If you don't believe me, equip yourself with a Schaffner and try dumping a fast-rise time 2kV spike into nearby metalwork...
Before going for a drive with anyone, ask them if they have insurance or, if not, if they would sign up for it it if it was free. If they say "yes" then you know they are terrible drivers and/or their car is in dangerous condition.
Best regards, Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Are you joking? I don't see a smilely. I can run my PC for 2 or 3 weeks without lockup. Does that prove that Windows 2000 has *NO* bugs? Funny, it usually doesn't go much beyond about 30 days without locking up.
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Rick "rickman" Collins
rick.collins@XYarius.com
The first watchdog timers I came across was in 1980 and had been included in the product for a year or two prior to that. As this was roughly the dawn of embedded processing it is not what I would call "fairly recent."
As do many newer systems, too, but this alone is, at best, a specious argument against WDTs.
BTW, the product to which I refer is the control panels for the 440 line of video/audio/timecode routing switchers produced by Grass Valley Group for the television broadcast industry. These were 8048-based, developed on 8080-based Intel MDS-230 (Blue Box!) development systems, and communicated serially with Z80-based controllers. I miss those days, not so much for the processors and tools but because the economics at that time allowed engineers, rather than accountants, to call the product development shots.
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Michael Kesti | "And like, one and one don't make
Ah... the Intel MDS . I still miss the editor, CREDIT... Around '83 I used to tote around the MDS's little brother, the iPDS... which had 5-1/4" disks - whoa! radical!
time
development
Errr... yeah, but do you remember how much those suckers used to cost? I think the iPDS cost us (with ICE, which was around half of the total, IIRC) around 13 kilobucks... Back then development systems were major capital investment. Nowadays it's a PC and GNU ;).
In various guises there have existed forms of watchdog 'timers' even in machinery before computers, the concept was transferred from various other spheres (even the night watchman doing his rounds) to computing.
I remember dealing with small quantity testing of Watchdogs for PDP-11's circa 1979 which had loud sounders attached to them, also the one that was designed for the QBus writing the diagnostic setup programme a few years later. These used standalone timers and even one shots so there was minimal logic to be affected by system activity and go wrong!
Even the one I dealt with circa 1979 was a design at least 2 years old as it was a repeat order.
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Paul Carpenter | paul@pcserv.demon.co.uk
Main Site
I'm intrigued! I only came across them in the context of embedded micros (late '70s), but on reflection I can imagine they'd be useful thingies in non-embedded contexts. However, I presume still within the realms of hardware/software integration? Pray tell!
We used them in the mid to late 60's on process control systems. On a dual system, the watchdog did two things - it switched the process control bus to the backup computer and rebooted it. The control database was piped once per second from the control computer to the backup on a high-speed core-to-core link, and the reboot took less than a second. This was from a head-per-track disk, and the biggest system had a whole megabyte of memory, so it didn't take long :-)
On single-processor systems, we sometimes used a sort of long-period mechanical watchdog. If there was a power interruption, the system would recover when power was restored, and the watchdog would enable the decision as to whether to pick up the process where it left off, or stay in failsafe and yell for an operator.
On Wed, 26 May 2004 17:37:52 +0100, "Steve at fivetrees" wrote: [...]
It wasn't a bad editor at the time. I liked it so much, I wrote a paper for my employer using it. This was back in the day when SOP was to write it out longhand and hand the chicken scratch to a secretary. This was also before I got used to Windoze and computers that crashed, so I spent about 3 hours on it before trying to save it.
Unfortunately, I made a typo and tried to save the file to the system disk -- which was full. "Insufficient space" error message followed by -- the ISIS prompt. Game over. Thanks for playing. Aargh.
The second version of the paper only took about an hour and a half, and was probably better overall. But I learned my lesson (one of them anyway).
My main background is also in process control (mainly temperature control). From working in Chicago in the early 80s I recall that "watchdogs" (or was it "policemen"?) were mandatory (insurance-wise) on certain processes in certain states, but these were simply over-temperature/pressure failsafes... or have I got that all backwards? A lot of neurons have flowed under the bridge since...
Another "me too" moment. I used to do all my documentation with it. The R&D secretary was unsure whether to thank me for saving her some work, or curse me for making her redundant.
I loved those macro scripting facilities... much fun. I've yet to find a modern editor that is as flexible in that respect (although one day I'll learn how to use vim or emacs properly...).
Ah, well, our MDS and iPDS both had *2* drives - so nerrr! ;)
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