Have you switched it off and on again?

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llondel
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Have you switched it off and on again?

#1 Post by llondel » Sun Apr 05, 2020 12:40 am

Anyone heard more about this? I did check the date on the article and it's definitely dated 2nd April.

https://www.theregister.co.uk/2020/04/0 ... tale_data/
The US Federal Aviation Administration has ordered Boeing 787 operators to switch their aircraft off and on every 51 days to prevent what it called "several potentially catastrophic failure scenarios" – including the crashing of onboard network switches.

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Re: Have you switched it off and on again?

#2 Post by Alisoncc » Sun Apr 05, 2020 12:56 am

Back in the day when cutting C code for a crust, memory leakage was a significant trap for new players. Allocate chunk of memory as global variable. Then cycle through routine numerous times. After a while you would run out of memory as you gradually chipped away at available memory if the global allocation was not released. A reboot and the problem would go away. Sounds very much like the 787 problem. :p
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Re: Have you switched it off and on again?

#3 Post by llondel » Sun Apr 05, 2020 1:06 am

We used to try to work on the principle that all memory should be statically allocated, so no malloc or free, to avoid exactly this sort of problem.

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Re: Have you switched it off and on again?

#4 Post by PHXPhlyer » Sun Apr 05, 2020 3:24 am

llondel:
Don't recall the actual number but the 787 always had a hard limit on time limit between shut downs.

PP

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Re: Have you switched it off and on again?

#5 Post by TheGreenGoblin » Sun Apr 05, 2020 6:26 am

llondel wrote:
Sun Apr 05, 2020 1:06 am
We used to try to work on the principle that all memory should be statically allocated, so no malloc or free, to avoid exactly this sort of problem.
Managed to crash one the of the Vax PDP's on the network I was working many moons ago, having gone long on the malloc and short on sense if not the integer! Overwrote part of the operating system in RAM! Truly a SNAFU moment and a lesson in the sense of what you say!

One Vax, many Vaxen, far malloc man!
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Re: Have you switched it off and on again?

#6 Post by Alisoncc » Sun Apr 05, 2020 7:09 am

A VAX/PDP, Sir ??

As an applications engineer with Digital for many years VAX/PDP must have come after my time. VAX's were 32 bit and PDP11's were 16 bit. The VAX 780 and the PDP11/70 were the biggest machines in their respective categories. Remember configuring a core upgrade for a PDP11/34. Yup that was core memory. The VAX750 came out in my time. Did do a course at Malborough on MicroVMS just before we parted company.

Still got a whole swag of cerificates from DEC qualfying me as VAX780 sys admin. Happy daze.
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Re: Have you switched it off and on again?

#7 Post by Boac » Sun Apr 05, 2020 7:14 am

You have to hope the 51 days cycle doesn't pop up mid-Atlantic.

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Re: Have you switched it off and on again?

#8 Post by Alisoncc » Sun Apr 05, 2020 7:26 am

Surely Boac, there was a checklist for the "Blue screen of death" situation?
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Re: Have you switched it off and on again?

#9 Post by Pontius Navigator » Sun Apr 05, 2020 7:32 am

Switch off, wait 5 minutes . . .

Have you noticed in-flight entertainment systems use Linux?

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Re: Have you switched it off and on again?

#10 Post by TheGreenGoblin » Sun Apr 05, 2020 7:33 am

Alisoncc wrote:
Sun Apr 05, 2020 7:09 am
A VAX/PDP, Sir ??

As an applications engineer with Digital for many years VAX/PDP must have come after my time. VAX's were 32 bit and PDP11's were 16 bit. The VAX 780 and the PDP11/70 were the biggest machines in their respective categories. Remember configuring a core upgrade for a PDP11/34. Yup that was core memory. The VAX750 came out in my time. Did do a course at Malborough on MicroVMS just before we parted company.

Still got a whole swag of cerificates from DEC qualfying me as VAX780 sys admin. Happy daze.
Twas a PDP 11 linked to a herd of "VAXen" and a subnet of very early IBM PC's running a primitive telnet emulator if my memory serves me correctly. I was neither a DEC VAX nor PDP specialist, like your good self, but an IBM System 36/RPG2 jockey who could code in C having come up the Unix route. I guess it showed because I screwed the PDP's core memory up royally. Such imprecision would have made Ken Olsen cry I guess.
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Re: Have you switched it off and on again?

#11 Post by Boac » Sun Apr 05, 2020 7:38 am

Alison wrote:Surely Boac, there was a checklist for the "Blue screen of death" situation?
indeed there is, Alison, but due to the way it is designed it comes up on the ECAM. =))

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Re: Have you switched it off and on again?

#12 Post by Alisoncc » Sun Apr 05, 2020 8:19 am

TheGreenGoblin wrote:
Sun Apr 05, 2020 7:33 am
Twas a PDP 11 linked to a herd of "VAXen" and a subnet of very early IBM PC's running a primitive telnet emulator
Interfacing IBM's SNA to DEC's DDCMP. So much fun, t'was. This all preceeded TCP/IP. Never reckoned TCP/IP would come to anything.

Excuse digression into IT stuff. Aviation is just so boring these days. Don't know anyone who is still in the industry. Do know someone who has just started a business manufacturing donkey whips. :((
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Re: Have you switched it off and on again?

#13 Post by Boac » Sun Apr 05, 2020 8:39 am

"donkey whips." - excuse me, boss. We need to know why you want one.................. :))

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Re: Have you switched it off and on again?

#14 Post by TheGreenGoblin » Sun Apr 05, 2020 8:42 am

Alisoncc wrote:
Sun Apr 05, 2020 8:19 am
TheGreenGoblin wrote:
Sun Apr 05, 2020 7:33 am
Twas a PDP 11 linked to a herd of "VAXen" and a subnet of very early IBM PC's running a primitive telnet emulator
Interfacing IBM's SNA to DEC's DDCMP. So much fun, t'was. This all preceeded TCP/IP. Never reckoned TCP/IP would come to anything.

Excuse digression into IT stuff. Aviation is just so boring these days. Don't know anyone who is still in the industry. Do know someone who has just started a business manufacturing donkey whips. :((
By the stage the IBM System 38, which was very much part of IBM's System Network Architecture, came onto the market they had bundled a handy little SNA compliant tool called PC Support (now i-Series Client Access) to provide inter connectivity with the PC. One of the nice additional features this tool was the ability to link using an IP address to networks running TCP/IP. PC Support was TCP/IP compliant but wasn't TCP/IP per se (OSI 7 level model and all that good stuff). My plan was to link from the PC network running PC Support to the PDP-11 using TCP/IP and thence to the VAX machines on that network running DIGITAL TCP/IP Services for OpenVMS. Great fun and it worked, my faux pas on the 16 bit interface program on the PDP-11 notwithstanding.

I made a living making odd machines talk to each other and in my time made CNC machines talk to SNA compliant AS/400's and even BBC Micros in a hydro lab talk to machines on a SNA compliant network, the latter effort using 6250 assembler on the BBC machines All great fun as you say.

Perhaps we should set up a nerd's corner to gather and share IT war stories. I personally would love it.

Alternatively we could just set up Bondage Corner and go the whip route as Boac implied! =))
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Re: Have you switched it off and on again?

#15 Post by Alisoncc » Sun Apr 05, 2020 10:11 am

Boac wrote:
Sun Apr 05, 2020 8:39 am
"donkey whips." - excuse me, boss. We need to know why you want one.................. :))
Well known marketing case study relating to failure to diversify. Did it in my MBA at Wits. Owner of firm had long line of ancestors going back centuries making donkey whips. His father, grandfather and great grandfather had all made donkey whips. Had incredibly good reputation and tons of goodwill. Unfortunately he failed to recognise little demand for whips amongst the motoring public.
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Re: Have you switched it off and on again?

#16 Post by TheGreenGoblin » Sun Apr 05, 2020 10:18 am

Alisoncc wrote:
Sun Apr 05, 2020 10:11 am
Boac wrote:
Sun Apr 05, 2020 8:39 am
"donkey whips." - excuse me, boss. We need to know why you want one.................. :))
Well known marketing case study relating to failure to diversify. Did it in my MBA at Wits. Owner of firm had long line of ancestors going back centuries making donkey whips. His father, grandfather and great grandfather had all made donkey whips. Had incredibly good reputation and tons of goodwill. Unfortunately he failed to recognise little demand for whips amongst the motoring public.

A Wits alumnus..!. :)
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Re: Have you switched it off and on again?

#17 Post by Boac » Sun Apr 05, 2020 10:59 am

..and you think we believe you, Alison?

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Re: Have you switched it off and on again?

#18 Post by TheGreenGoblin » Sun Apr 05, 2020 11:07 am

Boac wrote:
Sun Apr 05, 2020 10:59 am
..and you think we believe you, Alison?

The University of Witwatersrand had and still has a very good MBA course. I am delighted to hear that Alison has trod the corridors up there in Braamfontein although I tend to be a University of Cape Town chauvinist .. :-bd
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Re: Have you switched it off and on again?

#19 Post by ian16th » Sun Apr 05, 2020 11:48 am

A proper Process Controller wouldn't let you overwrite memory, be it occupied by Operating System or Application Code.
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Re: Have you switched it off and on again?

#20 Post by Boac » Sun Apr 05, 2020 11:49 am

Heavens forfend, Sir, that you should think I cast aspersions on the lady's qualifications! It will be Mice at dawn on the common by the Oak tree for you! I was referring to the rather 'dubious' cover for the interest in the item as in "Do know someone who has just started a business manufacturing donkey whip".

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