Bad command or file name

Anyone recall "what is this"? i.e. "Bad command or file name" If you know, you are old school.

We purchased computer for the first time in 1989 (before 27 year), opened boxes, finally figured out how to hookup everything & turned it on. Guess what next! anything we did for next month, we got only one answer, that is "Bad command or file name" It took more a than a month to learn that, this is the computer, it has it's own language & SYNTAX! if you don't know that language & SYNTAX, you will only get "Bad command or file name" If you mess with ... that, you get ... that.

The computer  was PC AT (called Advance Technology!) I think it was 8086 CPU, no hard disk, can boot only from a large floppy disk only. I don't actually remember everything about this experience.

Slowly we learned & run variety of program on that machine!

Lotus 123, HPM (Harvard Project Manager), Wordstar (Control B for bold text!), AutoCAD?

Yes AutoCAD without mouse! It was way more complicated to justify & buy newly invented mouse, then use keyboard! Sweet memory, thought to share my experience.