What I heard is that the for a while at first, the Space Shuttle was being run by Dec PDP-8E computers using core memory. They are normally the size of a suitcase. And a digital watch is probably 100 to 1000 times more advanced than that! But, those computers were well understood and considered highly reliable.

My Perl language forecasting program has more than 7000 lines of code at the moment. And it takes only a fraction of a second to compile it and get it running. But for certain applications it has to load and process hundreds of thousands of data lines and do many millions of calculations. Those things take some time even with a relatively fast computer. After all of those data are processed and the arrays are organized it can then start working on the project at hand.

An earlier .exe version of my Etdprog forecasting computer program is freeware. You can download and run it and see what it does. Because it is an exe program it doesn't need a compiler. It does need to run on a regular PC using Windows XP or Vista. It will probably also run on Windows 7.