Forums

How to choose a firmware partner

Started by robi...@tesco.net May 26, 2004
Steve at fivetrees wrote:
> "Alan Balmer" <albalmer@att.net> wrote in message > >>>> The watchdog timer is a fairly recent invention, millions of >>>> older systems run fine without them. >>> >>> It's exactly as old as embedded microprocessors. (I know. I >>> was there.) It'sdumb having one without the other. >>> >> No, it's much older than embedded microprocessors. > > 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!
Older than that. Back in vacuum tube days they took the form of retriggerable oneshots or the equivalent. Thyratrons were known to enter the picture. -- Chuck F (cbfalconer@yahoo.com) (cbfalconer@worldnet.att.net) Available for consulting/temporary embedded and systems. <http://cbfalconer.home.att.net> USE worldnet address!
On Wed, 26 May 2004 20:57:53 +0100, "Steve at fivetrees"
<steve@NOSPAMTAfivetrees.com> wrote:

>"Dave Hansen" <iddw@hotmail.com> wrote in message >news:40b4ee34.151436706@News.individual.net...
[...CREDIT story...]
> >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...).
Coincidentally, the paper I was writing was sort of a farewell letter, describing lessons learned and possible future directions the division I was working for could take to improve products and the development process. I was leaving for a new job in another division of the same company, where I would be using EMACS under VAX/VMS.
> ><snip salutory tale of backups and full system disks> > >Ah, well, our MDS and iPDS both had *2* drives - so nerrr! ;)
As did ours. The system disk was in the first drive, and the data disk in the second. It's been far too long for me to remember the actual command and file syntax, but to use an MS-DOS analog, I invoked the "save file" function, was prompted for a filename, and I entered "a:memo.txt" or perhaps just "memo.txt" when I meant "b:memo.txt". IIRC, ISIS used numbers rather than letters for the drive specifier, but you get the idea... Regards, -=Dave -- Change is inevitable, progress is not.
>>>> The watchdog timer is a fairly recent invention, >>> >>>It's exactly as old as embedded microprocessors. > >> No, it's much older than embedded microprocessors. > >I presume still within the realms of hardware/software integration?
Roman soldiers sounded off in turn while pulling guard duty. If the voice from the east wall didn't happen, the entire regiment would be woken up to investigate. That system was a watchdog timer. -- Guy Macon, Electronics Engineer & Project Manager for hire. Remember Doc Brown from the _Back to the Future_ movies? Do you have an "impossible" engineering project that only someone like Doc Brown can solve? My resume is at http://www.guymacon.com/
On Wed, 26 May 2004 12:30:02 +0100, "Steve at fivetrees"
<steve@NOSPAMTAfivetrees.com> wrote:

><robin.pain@tesco.net> wrote in message >news:bd24a397.0405260202.5241051c@posting.google.com... >> How to choose a firmware partner: >> >> Ask if it's policy to enable the watchdog timer. The correct answer is >> "no". > >Utter twaddle.
I have never even considered of using a watchdog timer, but might reconsider, if I had to design something for high radiation (space) environment with SEUs etc. In any safety critical systems, I would not even consider to use any processor based (or even sequential logic based) systems, but instead rely on mechanical, pneumatic or hydraulic systems.
>> 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. > >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...
I have not been working with hardware recently, but by impression was that the CE requirements required that the device should withstand a few kV charged into a few nF capacitor and then discharged at the metalwork _and_ the input and output pins. In addition to pin protection, this also requires that you pay attention to ground plane design. Paul
On 26-May-2004, rickman <spamgoeshere4@yahoo.com> wrote:

> Are you joking?
Yes. -Hershel
"Paul Keinanen" <keinanen@sci.fi> wrote in message
news:av0ab0ped1or7p2r9eer4gkesg1972tn5j@4ax.com...
> I have never even considered of using a watchdog timer, but might > reconsider, if I had to design something for high radiation (space) > environment with SEUs etc.
<Sigh>
> I have not been working with hardware recently, but by impression was > that the CE requirements required that the device should withstand a > few kV charged into a few nF capacitor and then discharged at the > metalwork _and_ the input and output pins. > > In addition to pin protection, this also requires that you pay > attention to ground plane design.
<Sigh> Sorry, I'm tired. I'll let someone else point out why you're not entirely wrong, and why watchdogs are indispensable anyway. Steve (who has been working with hardware recently) http://www.sfdesign.co.uk http://www.fivetrees.com
"Alan Balmer" <albalmer@att.net> wrote in message
news:bpq9b01m8va4ss24s9p6d7jgrtkv3alvvi@4ax.com...

> 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 :-)
A full megabyte....in the 60's?....that's pretty big. I programmed on WWMCCS GE/Honeywell mainframes in the early 80's that didn't have a full megabyte of magnetic core memory.
"Anthony Fremont" <spam@anywhere.com> wrote in message
news:M0btc.6002$lY2.4293@fe1.texas.rr.com...
> > "Alan Balmer" <albalmer@att.net> wrote in message > news:bpq9b01m8va4ss24s9p6d7jgrtkv3alvvi@4ax.com... > > > 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 :-) > > A full megabyte....in the 60's?....that's pretty big. I programmed on > WWMCCS GE/Honeywell mainframes in the early 80's that didn't have a full > megabyte of magnetic core memory. >
I would be interested (and surprised) to know which computer had a megabyte of core in the 60's. see http://www.crowl.org/Lawrence/history/computer_list to help "refresh your memory" (bad pun). I worked on Elliot 920B's (not on the list) perhaps because it was military?? Phil
TROLL ALERT

<robin.pain@tesco.net> wrote in message
news:bd24a397.0405260202.5241051c@posting.google.com...
> How to choose a firmware partner: > > 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. > > Cheers > Robin
In article <auidnV-mQaNaWind4p2dnA@nildram.net>,
 "Steve at fivetrees" <steve@NOSPAMTAfivetrees.com> wrote:

> Ah... the Intel MDS <sigh of nostalgia>. I still miss the editor, CREDIT...
Stop, please! I'm getting all misty eyed. My first job out of university was with a small custom microelectronics company developing embedded systems for the oil and gas industry. We used the MDS but we only had one so we had to write the code on paper and our secretary typed it in for us. She became so used to this that she did the first level syntax check. We were also using PL/M as a programming language, 1702 EPROMs or battery-backed memory we used to load from the MDS and carried to the lab. I loved it when we could afford to get a PDP-11 with VT100 terminals. The editor was one of the best I've ever used. Sniff, sniff... Oh, and we were using watchdog timers in the mid-70s. Can't imagine a system without one or something similar, unless you're talking sync-matched processors like the old Northern Telecom DMS-100s I used to program for. ...Tom