The term beige box usually refers specifically to a generic clone of the IBM PC, but there was also a more general trend of even respected manufacturers housing electronics in beige boxes in the 1980s and 1990s.
In the late 1970s, Germany introduced a new workplace standard that only allowed light-coloured electronics in offices. Various other European countries quickly followed their lead.
As Europe was a pretty big market, by the 1980s, a lot of electronics were light grey or beige, from Akai's samplers, to the Apple Macintosh, Atari ST, Commodore 64C, and Commodore Amiga home computers, and even SUN SPARCstations. By the 1990s, computers were almost all beige, with the notable exception of the ever-stylish NeXT and SGI workstations.
It probably helped that having any single standard colour allowed computers to look consistent, even when its floppy disk drive, CD-ROM drive, and case were all manufactured by different companies. (This would even explain Akai's use of the colour scheme, where it not for the fact their beige cases invariably housed black floppy disk drives.)
- ThinkPad Deborah Dell & J. Purdy, 1999, ISBN 0-672-31756-7, pp. 174—175
Misc: Beige box | Manga Video