This article is from the MachTen & CodeBuilder FAQ, by Jaime Julca firstname.lastname@example.org with numerous contributions by others.
MachTen is one of the most compact UNIX operating systems available. The
MachTen 68K application itself consumes 2MB in memory. Since System 7 takes
roughly 2MB RAM, you can see that you need more than 4MB RAM in order to
have enough memory available for UNIX and Mac applications. A total of 8MB
RAM is recommended for Professional MachTen, especially if you are doing
software development or running X. The Power MachTen application consumes
about 3MB RAM; a total of 16MB RAM is recommendedfor Power MachTen.
The hard disk requirements can vary from 15MB to 90MB, depending upon
whether you install the development tools and the X Window software
components of MachTen.