More Eternal Verities

Computerworld - How Computers Process Math, Time and Money

• Computers always start counting from zero, except sometimes.

• Grabel's Law: Two is not equal to three - not even for very large values of two.

• Skinner's Constant: That factor which, when multiplied by, divided by, added to or subtracted from the answer you got, gives you the answer you should have gotten.

• Best's Law: If data resides in two places, it will be inconsistent.

• Estimating Time: Everything takes longer than you think or want. To estimate the time required for any given project, first guess at the time you think it should take; multiply that by 2 and change to the next higher unit of measurement. Thus, if you think you can complete a project in one hour, tell your boss you will need two days; if four weeks, ask for eight months.

• The 90-90 Rule of Project Scheduling: The first 90% of the project takes 90% of the time, and the last 10% of the project takes the other 90% of the time.

• When you get a computer to do a job for you, the time you save will usually be spent watching the computer to make sure it works properly.

• No matter how expensive you expect a system to be, it will always end up costing more.

The Futility of Programming

• The computer is always right. Programmers are occasionally right.

• Gutterson's Laws: Any programming project that begins well ends badly. Any programming project that begins badly ends worse.

• Klienbrunner's Corollaries: If a programming task looks easy, it's tough. If a programming task looks tough, it's damn-well impossible.

• Farvour's Law: There is always one more bug.

• Dykstra's Observation: If debugging is the process of removing bugs, then programming must be the process of putting them in.

Hardware

• Pournelle's Law: Cables do matter. When something doesn't work, always check the cables and their connectors first.

• Parkinson's Law of Data: Data expands to fill the space available for storage.

• Atkinson's Seventh Law of Computing: All disk drives fill up.

• Hardware/Software Paradigm: A program is a device to show up hardware faults; hardware is the equipment used to show up software faults.

The Customer Is Always Wrong

• You can make it foolproof, but you can't make it damn-fool-proof.

• When a system is designed so that fools can use it, only fools can use it.

The Disconnect Between English and Computers

• Fail-safe systems do. Operating systems don't. Machine-independent code isn't.