I have some observations to make.

## I just tested these systems:
MS DOS 6.22 runs in 384K of memory (1994)
MS Windows 3.11 runs in 2MB of memory with a full mouse driven GUI (1994)
Macintosh OS 7.53 runs in 7.4MB of memory , full GUI + TCP/IP (1996)
Macintosh OS 8.1 runs in 13.2MB of memory, (1997)
Macintosh OS 8.6 runs in 26MB of meomory, (1998)

OpenBSD 6.1 starts in text mode command line in 27MB of memory
OpenBSD 6.1 in Xenocara uses 65-80MB of memory to start up.

## from recollection:
Windows 7 800MB of memory (2009)

Parabola GNU/Linux starts in text mode cli using 150MB of memory
Parabola GNU/Linux in weston uses 300MB of memory