Apple Macintosh PowerBook 1400 - Manual (Page 126)

You see a message if you don’t have 70 MB (the amount necessary for the
standard installation) of available space on the disk you choose. Depending
on the installation options you select, you may need up to 120 MB. If there
isn’t enough space available, you need to remove files from the disk before
installing the software.
Step 4: Install the software
Click the fourth button to install the Mac OS and additional software.
126 Chapter 7
Click here.