Safety- Do you know what your hitch is rated at

Originally Posted by brulaz

And some of us actually used slide rules in a previous life ...

I still have my 3 slide rules, dating back to 1971-74, when I thought I wanted to be an electronics engineer.

One of the 3 is round. That really confuses people.

For Halloween one year I dressed up as a nerd/geek. This was not difficult. I wore a slide rule on my belt,among other things. Several people asked if it was a real slide rule. I was impressed that they even knew what it was.

Do a Google search on JAVA slide rule and you will find many working slide rules on the web, not that any of them have any real value. For many people it is probably the only way to show their grand kids the way it used to be.

During my high school days I had a standing bet with my friends. If they could catch me without a slide rule then I would give then 5 bucks. I never had to pay out.

SLIDE RULES NEVER NEED TO BE RECHARGED.

Originally Posted by PopBeavers

...
During my high school days I had a standing bet with my friends. If they could catch me without a slide rule then I would give then 5 bucks. I never had to pay out.
...

Uber-Geek!

I've often wondered how many of the early space explorations were based on slide rule calculations. Certainly the early rockets (Germany's V-series and others) had to be designed with slide-rules. The Apollo's?

And big bridges, the Empire state building and newer Skyscrapers... all before computers. How did they do it? It is amazing. Or maybe we're just spoiled.

[Mr. Adventure]

My understanding is that the Apollo program was done mostly on slide rules to 3 significant figures. Calculators came later.

I found one in a drawer a month ago. My grandchildren said "What's that?"

Warning, this is rather long...

The first time I saw an HP 35 calculator was around 1973. It was $400. The HP 45 came out a year later also at $400, dropping the price of the 35 to $200. For comparison, text books were usually less than $5. The estimate for the cost of books per quarter was $35. If you were an engineering student than the estimate was $50 for the first quarter.

We had a calculator lab. Calculators, that could add, subtract, multiply and divide were only a little bigger than an IBM Selectric typewriter.

If you know anything at all about a mainframe you might know that the name of the spooling program is HASP (JES2 today). HASP is the Houston Automatic Spool Program. SPOOL is its own acronym. So HASP in an acronym containing an acronym. This does not occur often.

I know that the then largest IBM mainframes were used for the APOLLO project. However. the first customer ship of an IBM mainframe was 1965. It would have been closer to 1968-69 before the larger ones were shipping. My guess is that the computer was only used in the later part of the Apollo program. All of the math programs were written in FORTRAN. To speed up the machine the operating system was modified to use memory for work files. In those days you had the source code to the operating system.

My first computer access was a System 360 model 40. It had 128k of memory. K, not Meg). There was 28k for the OS and 100k for the application. It is amazing what you can do in only 100k of memory. In the event of a power failure you could recover the data in memory, because it was ferrite core, so it was non-volatile.

I know from personal experience that to perform a stress analysis on 1/4 of a Dakota wheel will take 4 days on what was a small mainframe computer in 1988. Today you can do that on a desktop, but it will take awhile.

Somewhere around 1975 the HP 65 calculator came out. This is the one that was programmable and memory was what looked like a stick of gum. I heard a rumor that if the on board computers failed and communications with earth failed then they had a program for the HP 65 that could do the calculations. I have never seen this documented, it is just rumor to me.

I had an engineering teacher that learned to solve complex problems without a calculator. In his day slide rules were made of bamboo. Apparently, when you are stationed near the equator you can not use the slide rule because the humidity causes the bamboo to swell. As a demonstration he had students create a list on the chalk board of 20 random numbers with not more than 4 digits. A student at the back of the class had an HP 35. The teacher was able to add them up in his head and write down the end result faster than the student could do the same on a calculator.

Slide rules were sometimes referred to as slip sticks.

If you did not have a slide rule, and knowledge to use it, then you would not survive any engineering courses. If you were not proficient with it (efficient) then you would not have enough time to get an A on a test.

That is probably more than you wanted to know.

[Frenchy]

When I started work in 1965, our branch had just bought a Wang calculator system for $10,000. It was as big as a small filing cabinet. It had 16 stations but only four could be used at one time. It could only add,subtract, multiply, divide and do square roots. We thought we were in heaven because of the square root function. We did a lot of light calculations that required us to find square roots of numbers to many decimal places on data for every second of a three minute event. We did this for hundreds of events.

In 1970, a professor from a small college who worked summers in our branch brought his personal TI-?? calculator to work. It cost him $500. It was unbelievable to us because it did so many functions; logs, trig functions, square roots etc. We ended up buying several for our branch and shared them.

Things sure have changed.

I bought the TI-Programmer. At least I think that is what it was called. It had hex and octal capability. This would be around 1980. I believe that the cost was $200.