I taught C++ at a university and one of my previous students said that that class was the best class to prepare him for the real world.
Posts by swm
1014 publicly visible posts • joined 6 Jun 2015
Catch Java 22, available from Oracle for a limited time
Intern with superuser access 'promoted' himself to CEO
BOFH: I get locked out, but I get in again
Re: PFY's responsibilities
On the Dartmouth Time Sharing system we once changed the conversion tables so 2's were entered as 3's and vice versa. The output tables were also swapped so 2's looked like 2's and 3's looked like 3's. People entering programs with line numbers (remember BASIC) for some reason had the lines beginning with 3 sorting before lines beginning with 2.
This must have been 1965 or so. Oh well - I guess I'm more mature now.
If we plug this in without telling anyone, nobody will know we caused the outage
Re: Let's Check the Server Room Access Log
In the 1960's at Dartmouth we were running time-sharing on some GE computers. Every so often something would fail and the technician would run diagnostics and find nothing wrong. Bringing up the system we couldn't find anything wrong either. The technician caught on and ran diagnostics every morning. When asked, he said he was warding off evil spirits. Reliability was much improved.
One day his diagnostics failed but time-sharing ran perfectly. Further checking revealed the failure was in the "bit change zero" instruction that converted EBCDIC to friden flexowriter code or something like that. We couldn't figure out a use for this instruction so we didn't use it.
Dave's not here, man. But this mind-blowingly huge server just, like, arrived
Re: So, he was just fired ?
At Xerox we expected a shipment of several computers. They didn't arrive so the shipping company offered a reward for finding the boxes. It was claimed by a shipping clerk of an unrelated company. It seems the boxes had been sitting on the loading dock for a couple of weeks and no one had any idea of what they were or who they were for.
The good news is the shipping clerk made some money and we got our computers.
Europe's deepest mine to become Europe's deepest battery
Please install that patch – but don't you dare actually run it
Re: Nine nines and an explosion
At Dartmouth with our 100user time-sharing system we kept track of scheduled uptime. We counted any interruption as 15 minutes even though the system would come up much faster than that. Some months we were over 99% but other months we got as low as 97% (mainly due to total building power failures).
Getting to 99.9% (1/3 of a day per year) would be quite hard. More nines would require a total redesign of the power system, redundant computers etc.
Re: We dont go for "uptime" records
I've noticed twice problems with firefox on linux when I download a new version and don't restart firefox. Evidently the code is running partially on old software and partially on new software. Once it affected the screen saver and once it crashed firefox. Restarting firefox solved these problems.
Techie climbed a mountain only be told not to touch the kit on top
Re: What percentage?
When I was debugging the executive for a 100-user time-sharing system in the '60s I was debugging the shutdown fault. This was a massive CPU. So I power cycled the power repeatedly to cause the fault. The field engineer was not happy and said don't do this more than necessary. No hardware faults were caused by this (fortunately).
GPS interference now a major flight safety concern for airline industry
BOFH: Looks like you're writing an email. Fancy telling your colleague to #$%^ off?
Re: Excellent!
Going to the stockroom I once got a pint of "alcohol" to solve some film problems. Taking a closer look I discovered that it was spectroscopically pure ethanol. This is better than 95% or 190 proof. The bottle sat in our lab and little by little it was used to static electricity in a film camera. Worked perfectly.
New year, new bug – rivalry between devs led to a deep-code disaster
Re: The real lesson...
Multics was written in PL/1 as the higher level language gave better control of the system design. It was thought that they would lose a factor of 2 in performance but make it up in cleaner code. What happened was that various constructs in PL/1 were slow so they changed the compiler to optimize the code generator for these cases. This benefited everyone as their code also ran faster.
There was a switch for the compiler to optimize the code but soon it was discovered that the compiler ran faster with the optimize switch because less code was generated so they took the switch out and always optimized.
Higher level languages have come a long way (but the original FORTRAN compiler for the IBM 704 generated code that was quite fast).
War of the workstations: How the lowest bidders shaped today's tech landscape
Re: A lot of design points were being explored at that time
I used both Smalltalk-76 and Interlisp at Xerox. Smalltalk-76 had the best debugger I have ever seen: you could see all of the class variables and instance variables and execute statements in the context of either. The stack trace highlighted the actual expression of the call in the source code and the code was editable dynamically. Smalltalk also had multiple "threads".
Interlisp had a debugger that also was powerful but required more knowledge of the system to use.
They were both a joy to use.
You don't get what you don't pay for, but nobody is paid enough to be abused
Re: Resilience and redundancy
This happened on the early ARPANET where they had a northern route and a southern rout connecting the east coast with the west coast. The phone company routed them together somewhere around Kansas and a back hoe took them both out simultaneously.
That's when they learned about insisting on different routing for redundancy.
Linux Kernel of the Beast 6.6.6 exorcised by angelic 6.6.7 update
Wayland takes the wheel as Red Hat bids farewell to X.org
User read the manual, followed instructions, still couldn't make 'Excel' work
Re: Click, click, click, nothing happens
There was a screen saver that took a snapshot of the screen and slowly random bits on the screen would drop down to the next non-white bit below. Eventually there was a set of pixels at the bottom of the screen where all of the bits came to rest.
Another screen saver took a snapshot of the screen and slowly caused the image to "melt" causing weird distortions of the screen.
Revival of Medley/Interlisp: Elegant weapon for a more civilized age sharpened up again
Re: You /what/ Liam?
It is interlisp. I used it for many years at Xerox as my desktop. It had mail, text editing, a couple of lisp structure editors, etc. in fact, everything you needed to get your work done. If it crashed (e.g., due to building power failure), when it came up all of your windows were just where you left them.
I still miss it (and Smalltalk 76).
Don't fear the Thread Reaper, a Windows ghost of bugs past
Making the problem go away is not the same thing as fixing it
Workload written by student made millions, ran on unsupported hardware, with zero maintenance
Colleges snub Turnitin's AI-writing detector over fears it'll wrongly accuse students
Re: If it's as good as their other products...
When I taught computer science all of the students' submissions were run through a cheating detection program which gave a score between submissions. One term the checker flagged two of my students of having a very high degree of similarity, it was, in fact, the highest score that term.
So I printed out both submissions, did a diff (which showed nothing). I then looked closely at the two codes and noticed that the students were using a totally different approach. If they did copy code it would have been useless.
So I went back to the cheating checker output. It basically looked for syntactic similarities. Both students used a lot of System.out.println s for debugging and the cheating checker had matched them all up even though they were printing different things.
So I just threw everything in the trash and never mentioned it to the students involved.
Getting to the bottom of BMW's pay-as-you-toast subscription failure
Re: if you tolerate this then your chilled air will be next.
Dartmouth created a time sharing system in 1964. It ran on a GE-225. It was later upgraded to a GE-235 which was three times faster and had more instructions. Of course the students used all of the extra instructions on the GE-235.
Since this was done on an NSF grant everything was public. Someone in GE got the idea of selling time sharing systems. So they got a GE-225 (and DN-30 etc.) and all of the source code. At which time they discovered that the code wouldn't run because of the use of GE-235 instructions. So they replaced the GE-225 with a GE-235 and put a wait loop in the executive to slow the machine down to GE-225 speeds. The code was labeled for exactly what it did. The customer was happy, GE was happy, and a lot of useless cycles were burned in the wait loop.
Chap blew up critical equipment on his first day – but it wasn't his volt
Re: Should this be so easy?
In the early days at college there was a planned power outage so we got a generator to run the studio. We then pulled the main breaker and made an extension cord with male plugs on both ends. one was plugged into the generator and the other into a convenient wall socket. Everything worked except the zip cord between the two plugs was quite warm to the touch. We had to be careful not to bunch up the zip cord to keep the temperature down. The generator was fueled with gasoline which we kept in glass jugs which we filled at the local gas station.
I'm glad OSHA wasn't around then.
Extra points: count the number of safety principles that were violated.
I'll see your data loss and raise you a security policy violation
Re: Outlook...
This was my strategy for paper documents. I would have several piles of papers, notes etc. in my office. I could remember which pile a document lived and using the principle of 1 inch per month allowed me to retrieve documents quickly.
The clean desk policy idiots didn't like this but, since they couldn't find anything in my office, I got a conditional pass.
Japan complains Fukushima water release created terrifying Chinese Spam monster
Windows screensaver left broadcast techie all at sea
India lands Chandrayaan-3 spacecraft on Moon, is the first to lunar south pole
Lesson 1: Keep your mind on the ... why aren't the servers making any noise?
Resilience is overrated when it's not advertised
The price of freedom turned out to be an afternoon of tech panic
Re: Spreadsheet imports
I remember at the college where I taught, one of the professors moved a column vertically in a spread sheet and excel helpfully tracked all of the cell bindings to their new location.
When I did grading with a spread sheet I always added a perfect student. If this student didn't get 100% after all of the formula crunching I knew something was wrong.
How to get a computer get stuck in a lift? Ask an 'illegal engineer'
Nobody would ever work on the live server, right? Not intentionally, anyway
The choice: Pay BT megabucks, or do something a bit illegal. OK, that’s no choice
Re: short cuts
Another true statement is: "You cannot communicate a ground reference faster than the speed of light."
If you are running signals a "long" distance you should also run the ground reference in the same direction in the same cable.
I used to run high-speed signals through ribbon cable grounding every other wire in the ribon. I used source termination (100 ohm resister in series with the source). The signal would divide in two at the transmitter end and send 1/2 the signal to the far end. Whereupon it was 100% reflected (making a full signal at the remote end). when the reflected signal got to the driver end it was 100% absorbed by the series resisters. This worked even though there might be multiple pulses in transit.
Linux lover consumed a quarter of the network
Re: Rule one...
At the college I was attending, the police came to the computer center and said they found someone with several 9-track tapes and an incoherent story about them -- something about research or something. So we mounted the tapes and didn't find anything suspicious. Then we had a hard time convincing the police that it was perfectly normal for a computer scientist to have a load of tapes with a very confused story about them.
Douglas Adams was right: Telephone sanitizers are terrible human beings
One day the college radio station went down. Sure enough a telephone repair man was in the basement disconnecting our wires to the transmitter. He was using an extremely old diagram and figured that the best way to proceed was to disconnect everything and then wire things up according to his outdated diagram. Physically pulling him away from the terminal block and reconnecting the stations wires fixed the problem.
Turning a computer off, then on again, never goes wrong. Right?
Re: PC Engineers...
We had a file server at Xerox that powered down when the building lost power. There was a good file scavenger program that could put all of the pieces together etc. Running it showed bad records in a spiral pattern across the disk. Evidently, the heads retracted while still writing!
(Backups restored everything.)
Re: Reminds me of an old (early '80s) AI koan ...
At the college I taught at we were studying permissions on files. Some student set the access pits to 000 on his user account and locked himself. Had to go to support to fix this.
Not really the students fault - he was just experimenting (as he probably should).
Nobody does DR tests to survive lightning striking twice
Re: Lightning always finds a way... of least resistance.
Lightning is a strange beast. A lot of it is RF. If you ground a lightning rod with a wire that makes a sharp turn, the lightning will go straight. The wire used to ground a lightning rod is a coarsely braided conductor more than an inch in diameter. All of the building gutters should be connected to the ground wires with a 1 inch wide copper strip. The actual ground to earth should be a 12 foot copper rod driven into the ground, preferably at three places around the house. The ground system should be wired to the electrical ground (that, by code, is a 6 foot galvanized pipe).
Remember, lightning rods attract lightning so you'd better be ready when lightning strikes.
It's 2023 and memory overwrite bugs are not just a thing, they're still number one
Re: Code cut...
What ever happened to LISP? It is fast, memory safe etc. and a pleasure to program in. A modern LISP has everything you need except acceptance. The newer programming languages haven't learned the lessons of LISP and reimplement everything in a buggy or limited way. The first LISP 1.5 is over 60 years old.
California man's business is frustrating telemarketing scammers with chatbots
Hacking a Foosball table scored an own goal for naughty engineers
At college there was an early dollar bill changer. I figured it was there to be tested by the students. So I took a dollar bill, tied a string around it, and placed it in the machine and slid in the slide. A fierce tug-of-war ensued resulting in a shredded dollar bill and a dollar's worth of change. I then carefully arranged the shreds of the bill on the slide. It took the pieces and delivered another dollar's worth of change.
A year latter I saw another dollar bill changer so I roughed up the leading edge of the bill (a technique I learned to cause jams in IBM card readers) and shoved it in. It took the bill but didn't give any change. I complained and the person in charge opened up the machine and saw that the bill had jammed in the mechanism but didn't fall to a micro switch that would release the change. So I guess they learned something.