HLOTD (History lesson of the day)
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This is the world's first hard drive, invented by IBM. It weighed over a ton and stored a whopping 5 Megabytes of data. Picture taken in 1956. [First hard drive]
Was that the Flight Data Recorder or the Voice Recorder? :)
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Still remember working on the DEC 10 system in 1987, perhaps one of the first ones to be installed in Bangalore, India at the Indian Telephone Industries (ITI). Faintly remember that the storage device there was a magnetic tape drive. While writing programs (in FORTRAN then), it occasionally used to throw this message: "System shutting down in 5 minutes. Please save your files", followed by a countdown, till shutdown. Early versions of Windows used to do it best - throw up a BSOD :-)
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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Was that the Flight Data Recorder or the Voice Recorder? :)
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This is the world's first hard drive, invented by IBM. It weighed over a ton and stored a whopping 5 Megabytes of data. Picture taken in 1956. [First hard drive]
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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This is the world's first hard drive, invented by IBM. It weighed over a ton and stored a whopping 5 Megabytes of data. Picture taken in 1956. [First hard drive]
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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!
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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This is the world's first hard drive, invented by IBM. It weighed over a ton and stored a whopping 5 Megabytes of data. Picture taken in 1956. [First hard drive]
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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!
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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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)?
:thumbsup: :thumbsup:
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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This is the world's first hard drive, invented by IBM. It weighed over a ton and stored a whopping 5 Megabytes of data. Picture taken in 1956. [First hard drive]
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.
