P.S. Old-Polack to date My largest and most advanced Dos.Bat was 103mb in size and ran as an AI type of program running around on the network looking for un-synced files on systems and updating files and software as Needed, if it found a New computer that was added to the domain, it went and checked its software package and if needed would uninstall and reinstall the correct programs. Not bragging but dos programming I am good at, too bad no one needs it anymore... 
I started with a simple pricing spreadsheet on an old TRS 80 and kept adding to it until I could enter dimensions of a project and have it spit out the exact amount of materials needed, the standard package/unit sizes for each type material, how many standard packages/units of each, that needed ordering, how much of each was already in stock, check for any price increases. figure what the labor hours were, for each fabrication step as well as the total labor cost, add markups for profit and overhead, then would print out an estimate to submit to the customer, and if that was accepted, would print out the order forms to the different suppliers, track the order and delivery dates, adjust the inventory, and finally print out the invoice and envelope. The only thing it didn't do was lick the stamp.
I had four of those big floppy drives, and once I entered the dimensions from a blue print, I had to sit there to change disks, whenever it asked for a new one, to continue. Each main disk had it's own application to run it's part of the sequence, as well as pure data disks to read and write to. It was slow as cold tar by today's standards, taking most of a day to run it's course, but it reduced a two weeks if done by hand job to a single day. It seemed marvelous and incredibly fast at the time.
When I got a "modern" pentium 200 mmx computer, with Win95 OSR2, I couldn't find anything to convert that to be used with anything that ran on Windows, so had to keep the old TRS 80, just to run that app. It had developed over years, when I had little bits of time to make additions and changes, and got so big over time even I didn't know how I had done parts of it. The thought of rewriting it from scratch, to work with different type Windows' apps was horrifying, and never got done.
