Second-system effect

The second-system effect refers to the tendency of small, elegant, and successful systems to have elephantine, feature-laden monstrosities as their successors. The term was first used by Fred Brooks in his classic The Mythical Man-Month.^[1] It described the jump from a set of simple operating systems on the IBM 700/7000 series to OS/360 on the 360 series.

Explanation

Although expressed as a problem of software design, the second-system effect is observable throughout all human design effort. It is somewhat akin to the idea of "fighting the last battle."

People who have designed something only once before, try to do all the things they "did not get to do last time," loading the project up with all the things they put off while making version one, even if most of them should be put off in version two as well.

See also

• Anti-pattern
• Feature creep
• Inner-platform effect
• Software bloat
• Sophomore slump
• Unix philosophy
• Zawinski's Law of Software Envelopment

References

This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.

External links

• Things You Should Never Do by Joel Spolsky, about the Netscape project.
• Rewriting Software, in Notes on Haskell.
• Rewrites Considered Harmful? by Neil Gunton
• The Big Rewrite by Chad Fowler.