BGD — The Little Green Desktop That Grew Up
GEM was the graphical desktop environment that shipped on the Atari ST from 1985. It gave the ST a consistent, window-based interface at a time when most home computers were still command-line machines — and for a decade, an enormous catalogue of serious software was built on top of it: music tools, DTP applications, graphics programs, professional utilities. The ecosystem was real and deep.
The Atari ST’s BLiTTER chip was designed for one thing: moving rectangles of
pixels around as fast as possible. It’s not a processor. It can’t branch. It
has no ALU. And yet, buried inside it is a smudge mode that turns its halftone
pattern registers into a 16-entry lookup table — which means, if you’re
creative enough with your data layout, you can coax it into doing arithmetic.