Jeff Atwood asks What Can You Build in 600 Lines of Code? As someone whose entire career is based on writing the shortest programs I can, let me take a little obnoxious trip down memory lane.
In the mid 80's, Paul Somerson was Executive Editor of PC Magazine and ran the "back of the book" where all the programming stuff appeared. The Programming column featured mostly handy command-line DOS utilities, and the criterion was 500 bytes of machine code in a .COM file — up to 1K if the program was "really cool." We wrote them in 8086 assembly language, of course, so perhaps the actual line count exceeded 600 lines, but the byte count is easily calculable if you have the old issues.
Here are my PC Magazine utilities from a three-month period back when I was Jeff Atwood's age:
DDIR, a double-column directory display (10/1/85 issue): 800 bytes.
VTREE to display directory trees with line-drawing characters (10/29/85 issue): 512 bytes.
SWEEP to execute a command in nested directories (11/12/85 issue): 592 bytes.
WAITASEC to call back scrolled-off lines (11/26/85 issue): 760 bytes.
KEY-FAKE for batch files. It shoved keystrokes into the keyboard buffer to be consumed by the next executed program (12/24/85 issue): 536 bytes
MONOGRAF.DRV for Lotus 1-2-3 that let you view bar graphs on the monochrome display with character-mode video boards (12/10/85 issue): 528 bytes.
By this era, the actual assembly language listings were not printed in the magazine. Instead, PC Magazine had an Interactive Reader Service accessible by modem and a phone number in the 212 area code. Be sure to use the XMODEM protocol to download the files!
Instead of assembly language listings, the articles included a listing of a BASIC program with multiple DATA statements (8 numbers per line with a checksum) that generated the .COM file for you. That's how I was able to determine the byte count of these old utilties so easily.
Where are the actual assembly language listings now that the PC Magazine Interactive Reader Service is no more? I would say that they are pretty much gone into that great bit bucket in the sky. (Too bad they weren't printed in the magazine, because as we all know, paper is forever.)