Skygod
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Re: Did you ever...?

Mon Nov 28, 2011 4:51 pm

Having just read the post on theregister.co.uk, it reminded me of the stupid stuff we used to do at Dixons etc....

The trustees are upset that there are so few 10-year-olds learning how to write even simple programs, that there are not enough teachers with the skills to teach computer science for beginners, and that the days of scamps typing in REPEAT:PRINT "Hello, world! ":UNTIL FALSE on a machine in a computer shop and legging it are long, long gone.

Mine was a simple
10 print "The staff here are useless and haven't a clue how to stop this!";
20 GOTO 10

:) :) :)

There was a line 15 about echoing a 'bleep' and if my memory is correct is was something like echoing chr(07). (it was many years ago, but I do know that the staff got really hacked off as they were not supposed to change anything on the display systems and most had no knowledge of how to 'break' the program(me).

Wicked....... (but fun to a teenager)

kme
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Re: Did you ever...?

Mon Nov 28, 2011 4:55 pm

In the DOS days I'd some fun (I was young and stupid!) changing the prompt from "C:\" to "Enter password: " on other, older peoples machines. :-)

Skygod
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Re: Did you ever...?

Mon Nov 28, 2011 5:02 pm

Quote from kme on November 28, 2011, 16:55
In the DOS days I'd some fun (I was young and stupid!) changing the prompt from "C:\" to "Enter password: " on other, older peoples machines. :-)

Oh, the days of having to set prompt $p$g in the AUTOEXEC.BAT

Hell, I remember having to set the date on every boot in DOS 1

obarthelemy
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Re: Did you ever...?

Mon Nov 28, 2011 5:40 pm

after messing arround with PS1, I'm looking back fondly at $prompt. And don't get me started on whatever screen calls its bottom line, even the name is unfathomable...

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Jongoleur
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Re: Did you ever...?

Mon Nov 28, 2011 7:32 pm

@Skygod:

Or WHSmith, or Boots, or...
ASCII 7 only worked on certain machines, but setting the screen to black, with a black border and black text was fun too.

Thank god they didn't have Asbos then!
I'm just a bouncer, splatterers do it with more force.....

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johnbeetem
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Re: Did you ever...?

Mon Nov 28, 2011 7:46 pm

As an undergrad we had a shared PDP-11 mini-computer. It was used for machine language programming and computer organization classes, but was also available to any student who was willing to sign up for time at lower priority. I spent a lot of nights and weekends with that machine.

The PDP-11 had a wonderful instruction called RESET, which reset all the peripherals. It took about 20 msec to execute. The best part is that it displayed the address of the RESET instruction in the address lights (binary), and the contents of register 0 in the data lights (also binary). It turned off all the other front panel lights.

So here's what my tiny program did: it executed RESET at address 0 with R0 = 0. This turned off all the front panel lights so it looked like the computer was completely dead. Every 20 msec it would check to see if the front panel switches changed, which was so fast that you couldn't see the lights flicker.

If the front panel switches changed, e.g., by a victim wanting to re-boot the computer, the program would print out "Go away, I am sleeping" on the screen and go back to its apparently-dead state. Great trick to play on newbies! Typical victim comment: "Is the computer still asleep?"

tufty
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Re: Did you ever...?

Mon Nov 28, 2011 8:30 pm

Hrm. A good many years ago, I worked for an "outsourcing" company out in West London. Mainly we dealt with hosting physical systems and doing maintenance. One of our clients was a manufacturer of domestic appliances[1], and their stock control system ran on a rather ancient piece of IBM hardware. Ancient enough that it had a hard drive around the size of a small fridge, and an 8" floppy drive, but I digress. It was also ancient enough to have been created in earlier, less paranoid, days, where everyone had access to everything on the system, and security rights were down to "you have physical access to a keyboard". A major part of the joy of this particular system was that *everything* was editable, including the script used to start up the machine itself. Not the startup scripts that ran after the OS was loaded, but the actual scripts that loaded the OS. And if the first script were, by "chance", to end up calling itself recursively, all hell broke loose.

Well, not quite.

What actually happened was we got on the phone to IBM at the South Bank, and they would taxi over this greying old man with a beard, who would power off the machine, disconnect the hard drive, connect the floppy drive, hold the 3-phase breakers closed and power the machine up again, plug in the hard drive whilst the machine was powered on, then reprogram the boot script using a hex keypad. All the time using language that would make a sailor blush. He would then deposit a large invoice, have a coffee, get back in a taxi, and leave. The entire process took around 3 hours.

Oddly enough, this happened fairly regularly. Usually at around the time the entry clerks came back from a leaving "do" on a Friday afternoon. At one point there was a round of compulsory redundancies at client HQ and it happened every day for a week.

This was the same place where (for another client, a food & wine distributor) I was called out to fix a breaking batch order processing job at 3AM. As usual for an outsourcing house, the crashing binary bore no resemblance to the source that was supposed to have generated it, or any other version of the source we had. The crash was being caused by an order for 100,000,000 items overflowing a number field. Remove line, rerun job, all looks OK, go back home to bed and deal with it in the morning. After some investigation later in the day, it turned out some tit had modified the ordering parameters such that cocktail sticks were now being ordered in units, rather than boxes of 500,000. <sigh>

Ah, and back in the TSO days, sending a fake crashdump to someone else's terminal.

Simon

[1] Motto - "Nothing sucks like Electrolux"[2]
[2] No, it wasn't Electrolux.

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Davespice
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Re: Did you ever...?

Mon Nov 28, 2011 8:54 pm

I used to swap monitor cables around on two adjacent PCs and then sit somewhere nearby to watch the confusion... :)

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abishur
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Re: Did you ever...?

Mon Nov 28, 2011 9:35 pm

We'd take screen shots of the desktop, then put all their icons in a folder on the C drive and delete them off the desktop. Then we'd take the screen shot, move the task bar to the top and hide it and set the image as the desktop background. The end result is that it would look like their normal desktop but none of their icons would be clickable and the task bar wouldn't work (and with it hidden at the top, odds were good that they wouldn't have it pop up on them as they were tying to click on the task bar in the image.)
Dear forum: Play nice ;-)

obarthelemy
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Re: Did you ever...?

Mon Nov 28, 2011 9:50 pm

I used to rent out servers for 3 months... for the price I paid to outright buy them. Often, the client would be late and keep them a few extra months, too.
I had a Mickey tie I put on for all my meetings with US customers, too.
Sorry. $ale$man fun.

Wooloomooloo
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Re: Did you ever...?

Mon Nov 28, 2011 9:57 pm

Back when we were learning "computers" (well, some of us a wee bit ahead of others) and the 5" floppy was the standard storage medium, the profs' "antivirus" (yes, viruses were _actually_ roaming the earth - sorry, our floppies - fairly freely back then) solution used to be to disable floppy drives and password protect the BIOS. Some of us, however, knew which single assembly line to type into the DOS "debug" tool to instantly whack the CMOS checksum, after which the BIOS panicked and let us in freely to enable the drive. Of course, we helpfully disabled again at the end of class, so they didn't much notice... Still, as these things go, too many caught on to the trick and eventually the drives' ribbon cables got physically unplugged in the end... ;)

tufty
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Re: Did you ever...?

Tue Nov 29, 2011 7:22 am

When we first got DOS machines, swapping a colleague's keyboard layout to german was always fun, too. It's almost, but not quite, qwerty...

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riffraff
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Re: Did you ever...?

Tue Nov 29, 2011 8:55 am

Are we talking DOS hi-jinks? How about handing your "buddy" a floppy of the "latest game" containing an autoexec.bat with the following commands:

ECHO OFF
CLS
ECHO Installing. Please Wait...
ECHO Y | FORMAT C: /Q > NULL

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riffraff
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Re: Did you ever...?

Tue Nov 29, 2011 9:11 am

Quote from tufty on November 29, 2011, 07:22
When we first got DOS machines, swapping a colleague's keyboard layout to german was always fun, too. It's almost, but not quite, qwerty...

In a part-time support job, I ran into my typing teacher from high school. Back then she had given me bad marks for looking at the keyboard and paper too often and not focusing on the source document. In the long run, that bad habit paid off for me as every make of machine back then had a slightly different keyboard layout.

My vengeance was changing her keyboard layout to Dvorak and watching her expression fall when she looked at her computer after having transcribed an entire letter without even once checking the screen. 8-)

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riffraff
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Re: Did you ever...?

Tue Nov 29, 2011 9:28 am

The worst prank anyone pulled on my watch was when I worked as a network technician at a local community college. The campus was connected by a large scale Novell network, but all of the administration facilities still resided on a TI-990 mini accessed by campus-wide VOD connections over the PBX.

Registration day was usually a nightmare, the only way to reset locked up terminals was to either pull and reconnect the RS-232 plug at the serial multiplexer or go to the remote terminal and do the same at the interface adaptor. After doing this about 15 times and staggering about the campus out of breath, I decided it wasn't a hardware problem.

After printing out a task list, I discovered one process that had spawned several hundred sub-tasks and was occupying nearly 90% of the system's resources. By the time I had managed to explain the concept of a "rabbit-job" to the system administrator and convinced him to kill the parent task registration hours were over.

joe
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Re: Did you ever...?

Tue Nov 29, 2011 10:28 am

On the BBC the *fx commands did a surprisingly wide range of things. If I recall correctly *fx 3,6 disconnected the keyboard input and the VDU text console output. The result being that the machine stopped being responsive and had to be re-booted.

This behaviour manifested itself strangely on the Risc OS Machines (Arc 310, 3000, 3010, 5000 etc). Obviously the keyboard stopped working, the mouse continued to work. And some bits of the screen got re-drawn and some didn't. My guess is that the graphics that were drawn by blitting characters to the screen are the ones that stopped (this is getting on for 17 years ago, memories a bit hazy). Great fun.

And then, of course, was the old Scroll Lock then F12 (which showed the command line but didn't allow the screen to scroll up). This effectively froze the screen and was a good way of reserving a machine for a friend.

Oh the nostalgia!

tufty
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Re: Did you ever...?

Tue Nov 29, 2011 1:16 pm

Quote from riffraff on November 29, 2011, 09:28
By the time I had managed to explain the concept of a "rabbit-job" to the system administrator and convinced him to kill the parent task registration hours were over.
Ah, "college computers". I went to a Technical College, now a "Regional College"[1], which was equipped with a minicomputer. The same minicomputer that I'd had to send batch jobs to via paper tape, teletype and acoustic coupler when at school, oddly enough. Anyway, it was supposed to have a maximum of 8 terminals attached, these had been multiplexed out to 64 - the machine was woefully inadequate and pathetically easy to crash. To fill in time between pub opening hours^H^H^H^H^H^HA-level courses, I was required to do a computing BTEC (which was also woefully inadequate) and, along with a few mates, finished the entire required syllabus in under a week. Which left much time for tooling around, which including borrowing the system programmer's manual and programming the machine in assembler. Scrolling messages across the front panel lights was one amusing trick we managed (debugging this involved sending someone to "look for a printout" in the operator's broom cupboard) but more often than not we managed to hang the machine itself. Such that we had "machine code" rights taken away in a rushed firmware update. At this point, it became war, and we went all out to crash the machine in the most inventive ways possible. I think one of the most "amusing" was a "rabbit job" that did nothing but bounce itself from terminal session to terminal session, sending large quantities of line feeds to the printer as it went; once the printer was out of paper, the print buffer filled up memory until it overwrote the stack, and *BLAM*...

And that's how I and a couple of others ended up having to do systems maintenance for 2 hours a week instead of getting bored in BTEC computing.

Simon

[1] I was enrolled, at least. Most of the time I was in the pub.

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riffraff
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Re: Did you ever...?

Tue Nov 29, 2011 2:48 pm

Quote from tufty on November 29, 2011, 13:16
I think one of the most "amusing" was a "rabbit job" that did nothing but bounce itself from terminal session to terminal session, sending large quantities of line feeds to the printer as it went; once the printer was out of paper, the print buffer filled up memory until it overwrote the stack, and *BLAM*...


I had a phantom who would strike at the various campus PC labs. He had a phenomenal collection of teleprinter art. Every few days I would find a locked up printer server and a ream of paper running out of the laser printer with some scantily clad or utterly nude pin-up babe from the 60's or '70's. I'd have to reboot the server, delete all of the files in the print queue and replace the document header. I never caught him. I was always, at best, seconds behind and, as usual, no one ever saw anything. Eventually it stopped, he obviously quit or transferred out.

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Jongoleur
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Re: Did you ever...?

Tue Nov 29, 2011 9:03 pm

At the Poly I attended in the mid 80s, the Computer Sciemce dept had their very own HP1000 mini computer - a sad beast that was almost as ready to go out to pasture as the DEC 20 that lived in glass enclosed splendour downstairs (it was one of those installations where the computer room had to be vacated within 30 seconds, or whatever, of the fire alarm going off...). Anyhow, we were "learning" Pascal using this cretinous machine; usually if only one person compiled a program, it would take two or three minutes. However we found that if everyone compiled at the same time, then the system would slow to a crawl, then crash. An ideal solution when an early dart was required!

To put this in perspective, at the time I had an IBM PC clone that could compile the same program under Turbo Pascal 3 in seconds. :-)
I'm just a bouncer, splatterers do it with more force.....

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riffraff
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Re: Did you ever...?

Wed Nov 30, 2011 5:17 am

Quote from Jongoleur on November 29, 2011, 21:03
At the Poly I attended in the mid 80s, the Computer Sciemce dept had their very own HP1000 mini computer - a sad beast that was almost as ready to go out to pasture as the DEC 20 that lived in glass enclosed splendour downstairs (it was one of those installations where the computer room had to be vacated within 30 seconds, or whatever, of the fire alarm going off...).


That made me think of the customs house broker my father worked for in the mid '80's. Their original offices were in a cramped and filthy old cotton warehouse near the airport. Their computing needs were initially filled by a terminal MUX and leased line to the DEC system in their sister office across the state.

As business grew, they purchased a PIC Systems mini, which wasn't a great deal larger than your average large tower PC, and placed it in the accounting department. They still had their leased-line access to the DEC, but most tasks were recoded for the new mini. It wasn't a particularly reliable little beast, prone to frequent crashes, but it was quick to reboot and significantly more reliable than their remote access.

As business continued to grow, the owner found new space for their offices, and alarmed at the little mini's performance, asked his consultant what he could do to improve reliability. Did he need a new and larger system? The consultant's considered response was, "Well, look where you've got it. It's dusty, you have smokers in here and it's stashed in the corner of this little office with traffic all around it. Plus the wiring in this place is awful and you should consider some sort of power backup. When you move, set aside a clean area especially for it."

Indeed he did. After the move, my father invited me to see the new spacious offices. The centerpiece was a state of the art pristine white glassed walled 20 square hermetically sealed independently air conditioned diesel generator backed computer room complete with hidden wiring under removable floor panels. There, in the center, all alone, sat little PIC Man, with it's nicotine stained and coffee-ringed case, looking for all the world like a whore in church.

kkolev
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Re: Did you ever...?

Wed Nov 30, 2011 9:13 am

Ah, the good ole fork bomb batch file was good for a chuckle:


start /m self.bat
start /m self.bat
start /m self.bat
start /m /w self.bat


if I remember correctly. Used to freeze your average win98se box after about 64 spawns.

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crundy
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Re: Did you ever...?

Wed Nov 30, 2011 4:47 pm

Hmm, my "trick" on the speccy was:

10 PLOT 128, 0: DRAW 0, 155, 2771 * PI

Give it a go in an emulator. Also, it uses Pi, so it is relevant to our interests.

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crundy
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Re: Did you ever...?

Wed Nov 30, 2011 4:56 pm

Oh wait, I just remembered something I used to do at school. On our network when you booted a machine it would go to a command prompt asking for your username and password and then it would boot windows. I wrote a compiled QuickBasic app which spat out the same loading junk and had a username / password prompt, but it would log the details to a hidden text file and then say "Wrong password" and start the login process again, so people just thought they had done a typo and tried (successfully) again. I learnt two things from this:

1) That password expirations should have a grace period. Our system would just stop you in your tracks saying "Your password has expired, enter a new one NOW!". Consequently the most common password I sniffed was "fireexit" :)
2) Gaining the teacher's admin password is pure gold when you are 17. I used it to promote a dummy account which was used for document storage to server administrator and had all kinds of fun (and never got caught)

I also wrote a macro virus and released it on the school systems. This was shortly after Winword/Concept had been discovered, and mine was the first (and probably only) macro virus to run on all versions of Word from v2 upwards. Unfortunately my "harmless prank" against the school backfired somewhat when my virus made it into the top 10 reported wild viruses that year :-\
I kinda stopped playing computer pranks after that.

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