Why do we call it a software "patch"?

In programming, and more generally in computing, a "patch" refers to a fix applied to a piece of software, in order to resolve a bug, or a security flaw.

This fix can exist in the form of a modification to the source code (the software will therefore need to be recompiled), or directly in the form of a binary (executable) file to be replaced.

The word "patch" is commonly used in French, and yet there are several valid literal translations, including the term "rustine" (a registered trademark of Louis Rustin), and which fits perfectly with the historical origin of the word.

Let's discover a piece of computing history together!

Back in the 1940s...

On August 7, 1944, Harvard University received the first large-scale digital computer, the Mark I.

Credit: Wikipedia

Sixteen meters long, and capable of performing three additions per second, this computer had to be programmed using punched cards. Each card comprised 10 rows and 23 columns (i.e. 230 bits) whose value depended on whether or not each point on the card was punched.

All these cards were linked together on long tapes, and since there were no conditional operators, the beginning of certain tapes was connected to the end of the same tape, in order to create a loop (in the literal sense).

It also had a second tape reader for input data.

It sometimes happened that once the instructions were written on the card, the execution turned out to be erroneous, and the code (or the input data) had to be modified, and to do this, holes had to be patched over (or new ones created).

To seal the holes, a piece of opaque adhesive tape was used ("patch of tape" in English), which corrected the instructions, as shown in the photo below.

Credit: Wikipedia

Over time, the storage media for software and data evolved, first to magnetic tapes that were cut and glued back together (still with tape), and it wasn't until the arrival of floppy disks and then CD-ROMs that it became (almost) impossible to physically repair data.

And yet, even today, the term "patch" has stood the test of time and is still used, even though many people don't know the origin of this word!