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Message Closed
modified 25-Mar-15 17:48pm.
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Cornelius Henning wrote: calculate prime numbers
Yes - those were our favourite programs - with others being implementations of the Newton Raphson method, Regula Falsi method, Simpson's rule and Gaussian Quadrature for numerical integration.
One other interesting program we wrote was called "Odd Order Equisum Square", just another name for a magic square program.
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I worked on a PDP-11/34a with 2 RK06 7meg word diskdrives (and a tape drive).
I wrote a directory sort program that directly modified the directory pointers,
(Skipping the slow step of loading into an indirect array, and then applying the
changes). it was SO much faster. With one issue. Apparently I had a bug, and I
cross linked 5 files in an infinite loop (directory enteries were a Singly Linked List).
So, when I went to do the directory, the last 5 files kept repeating. But the segment
of code was being run by the OS, and would not break. The drive head was going back
and fourth over 2 points, and the drive slowly started ROCKING... More and More.
A Mad dash to the front of the CPU to HALT the system. Forced an Odd Address Trap,
to avoid the reboot, and then I had to remove my account, losing my files.. Because,
like an idiot, I was working on the live system, without a backup. Pretty soon, I
learned how to do backups.
High School... We were lucky to survive some of our mistakes!
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Wow! Early day OS-level programming! Must have been very exciting! Some of the things you did would have made history - perhaps the first time in the world that someone did them.
Being a Mechanical Engineer, I was not so lucky!
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Not sure if it would have made any history. But I still remember when someone told me that the operating system was just a program.
That changed my whole world. I dug in, and I learned to hack the OS (RSTS/E).
Learned how System function calls worked (literally implemented as a VMT in the OS),
which was our version of an Interrupt. It was SOOO Cool.
I still remember things like:
A = sys(chr(6)+chr(A)+chr(B) ...)
So, this string was passed to SYS. It was pushed onto the stack, and CONSUMED in bytes.
The 6, for example, meant a privileged call. And the A was a value to indicate what call.
Like Killing a job. Then B would be the Job Number to kill. Or A could be LOGINS, and B would
be 0 for disable login and 1 for enable login).
I literally found the code in the OS that processed this stuff. But source was not available.
I had to decode the Octal byte stream from the system memory (I think 4047 was the jump command).
But realizing the Operating System was just a program... Wow, that opened all the doors.
I was rewrote the boot sector to change the message from "non-system disk" to "Good Going Valade!"
to tease a fellow student who always tried booting the wrong disk. He was SHOCKED to see his name,
and a little more than upset at me. (I was a little too cocky)
==
Hardware... Well, I pretty much fried everything I worked on. So I decided I was made for
software. LOL...
==
Do you have a day in Mechanical Engineering where you said "aha"... And realized that it was all about X (neutralizing various forces, compaction vs. expansion, material design)?
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Kirk 10389821 wrote: Do you have a day in Mechanical Engineering where you said "aha"
Not one, but several:
1. While pursuing my Doctoral Degree in Mechanical, we needed a uniform collimated sheet of laser light to illuminate a 3D photoelastic model. My Professor suggested a motor driven contrivance for that, and when put to practice, the 'sheet' of light turned out to be like an ameoba, simply because we could not meet the manufacturing tolerances needed. This set me thinking into looking at static, rather than dynamic / motor-driven ways. While going through all 'junk' in the lab, came across a solid glass cylinder, and a perspex cylindrical lens. Using these two, could produce what was needed - perfectly collimated, and uniform too. The Professor was very happy.
2. Again, during those days, needed to solve a system of two integral equations. The first implementation (in Fortran) caused floating point overflow. Faintly remember that the upper limit of a float turned out to be of the order of 10308 and a variable hit that limit. Showed it to my Prof, and we discussed. Turns out that there was another variable, which went to 10-308. Formulated a way by which these two came in pairs, so that their product was computationally tractable. This was also an 'aha' moment.
3. Another 'aha' moment was when I deviced a stepper-motor driven traverse mechanism, which gave 'wow' moments to my Prof; all using 'junk' in the lab.
All of the above was twenty years ago. In professional life, there have been some 'aha' moments. But after becoming a senior person, I let my team members get their own 'aha' moments, so that they also get personal satisfaction.
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They're installing it as a Flight Data Recorder on that plane
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Respect for International Business Machine (IBM)
Gaurav Arora
http://gaurav-arora.com
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Weren't those called "microprocessors" or something back then? 
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That is crazy man!
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I've heard about "walking" harddrives, as those things' heads (when in sync) would make them move across the floor... tlak about "system is running"
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Whilst working at BT in the 80's we took delivery of what we were told was the first 20Mb drive, it was the size of a desk pedestal and took 4 of us to lift it. we took delivery of another a month or so later as we filled it pretty quickly.
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Reminds me of my first hard drive for the IBM-PC, the Corvus. A huge, loud, expensive device - over $5,000 for 10 MB.
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I started working with them in the mid 1970s. They were about the size of a modern day dishwasher. Had platters - like vinyl records stacked about 5 high. I think they stored 400 MB. They were so big and expensive that peripherals were shared amongst several computers and I worked on a peripheral switch - how to switch hard drives, tape drives, paper tape, etc between computers.
I remember getting an IBM PC with a hard drive for the first time. Probably mid 1980s. 10 MB instead of floppy disks. We thought we had it made.
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Was that the Flight Data Recorder or the Voice Recorder? 
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According to Zeph up near the top of the thread, it is the Flight Recorder 
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Sometime around 1990 I went with a class to tour an IBM facility in San Jose, CA. One of the rooms we visited was full of the 25 MB version of this drive. The customer apparently did not want to upgrade the system ...
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In Apple terminology: it could hold one song
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That appears to be Grace Hopper in the plane.
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I wonder what the largest ever hard drive platter size was. I have one with about a 26" diameter sitting in my garage, salvaged by my dad from decommissioned equipment. He said it had about a 1 MB capacity. I have no idea what it came from.
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I have 2 leads on C# WPF positions with Financial Trading Application companies.
I'd be interested in hearing from anyone who's every worked in a role as a developer in a company like this.
They didn't ask for any prior experience in the industry, but I'm mostly concerned about what prerequisite knowledge I will need going in. Is it math intensive? Do I need a lot of experience with financial calculations?
I know every job/company is different, but I'm looking for some general feedback. Both positions are fairly high paying, so I'd like to find out what they're looking for before I dive too deep in.
Thanks
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Everything that I have read in the news indicates that the financial industry and accountants prefer "creative" math over accurate math.
Just an observation...
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the job listing did not list prerequisite or necessary experience?
If it's only WPF, I assume it will be high level programming (UI...)
I'd rather be phishing!
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You might be working with an existing system/framework. If so, then you will be doing maintenance work and maybe some new enhancements, at first. Being able to show that you can solve problems, quickly and correctly, is paramount.
I use to write software for a financial institution (forbes 500), which will remain nameless.
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Slacker007 wrote: I use to write software for a financial institution (forbes 500), which will remain nameless bankrupt.
FTFY 
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