Have you ever been working on a drawing and wanted to save it at the current point in time and still work in the current drawing? Well you can perform this task by copying the file using Windows Explorer, but it seems it would be a bit of work that isn’t needed if you knew about the SAVE command.
SAVE – Saves the current drawing in the same manner as Save As, but you are left in the original copy.
QSAVE – Quick save, saves the current drawing.
Now it seems a bit counterintuitive to use the SAVE command to create a copy of the current drawing, but that’s the way it works and I imagine it made sense at the time for the software developers. The QSAVE is the command used to simply save the current drawing.