Why do keyboards have an asterisk key?

Question

While we're all accustomed to using * as the multiplication symbol (not to mention other esoteric meanings in programming, command-lines, etc.) it is of course not actually the everyday standard symbol for multiplication. And yet, there is no × key on any normal keyboard.

Given the lack of × I can see why * was the next-best choice, but why is it there at all? What did it mean originally and/or what use did it have?

Every 'standard' "IBM-PC" type keyboard I can remember using had this symbol. The C64 had it. In any case it seems to go way back to at least the early 80s, I'd bet earlier.

Answer 1

Computer terminal keyboards needed to reproduce the symbols available on punched cards and paper tape. In the US, punched cards dominated the data-processing industry (communications uses tended to paper tape).

IBM punched card codes in particular were significant in the industry.

The IBM 026 keypunch (and its replacement the 029) had an asterisk. By the time online keyboards became interesting, the asterisk was already in use in various programming contexts, and therefore was still needed.

The 026 had different character sets (and encoding) available, but asterisk was common to most (all?) of the configurations. See this page for examples, but here is the FORTRAN set:

+-0123456789ABCDEFGHIJKLMNOPQR/STUVWXYZ =' .) $* ,(

You can regard that scanty set as the minimum requirement for any subsequent computer keyboard.

But why was there an asterisk on 026/029 card punches?

This authoritative document on coded character sets says, on page 66, that asterisk was added to IBM punch card codes 'somewhere around 1932' and was used for cheque protection. This was a 39-character set: alphanumerics, minus sign, ampersand, asterisk.

Therefore, the need for asterisk on data-processing equipment was settled long before stored-program digital computers came on the scene. And of course, if the processing equipment can use a character, it needs to be on the keyboards.

Answer 2

Keyboards have an asterisk because typewriters did, long before computers existed.

Typewriters, particularly mechanical ones, typically made a number of compromises to reduce the number of keys required. For example, many didn‘t have 0 or 1, and people used O and I or l instead. Likewise, × wasn’t needed since x could be used instead, or · (. half-up). The asterisk was used a lot (e.g. for footnotes, section separators, etc.), and no alphabetic character could replace it, so it was included in many popular keyboards (see for example Hemingway’s Underwood Portable or the Underwood 5).

Since it featured on most typewriters, it ended up being included in some of the character sets used for communications, and in early computer keyboards too (they started off as typewriters), and then in ASCII (via said communications character sets). See Why are the symbols on the number keys of PC & Mac keyboards different to ASCII keyboards? for details. By the time ASCII was standardised, * had taken on its mathematical meaning; it’s included in the mathematical symbols (p. 213).

Answer 3

The reason to use * instead of × is disambiguation. × looks very similar to x now, even more so in the early days of computing, before the laser printer became ubiquitous and you needed typesetting software and a printing press to produce an × that was distinguishable from an x.

According to this post, we can blame Fortran:

While it is now common practice to use an asterisk for multiplication, I don’t think that was the case before the FORTRAN programming language was developed at IBM by John Backus and his team.

Presumably, the asterisk was chosen — presumably because it was the non-alphanumeric symbol that most-closely resembled the customary × symbol that denoted multiplication, whereas the letter X could not be used, since FORTRAN used letters of the alphabet for symbolic variable names of variables and unknowns. Since there were no superscripts (nor subscripts) available, so exponentiation was indicated with a double-asterisk: ** (and parentheses were used to surround subscripts). Furthermore, the letter “E” was used (following a string of digits) to render numbers in “scientific notation”, e.g., 6.02×10²³.

The asterisk has been used as a multiplication symbol for a long time:

In the old days of arithmetic, many algorithms made use of the cross of San Andres to solve division and multiplication products and proportions. It may be for that reason that in 1631, Oughtred, chose this cross as a symbol for multiplication.

It experienced great acceptance, except by the mathematicians Gottfried W. Leibniz and Isaac Newton, who did not feel completely comfortable with the symbol. Leibniz, in 1698, in one of his letters to the mathematician Johann Bernoulli, writes: “I do not like the × symbol as a symbol for multiplication since it can be mistaken for x; … I often simply relate two quantities with a point and indicate multiplication with RS · PQ.”

...

For example, the Swiss mathematician Johann Rahn, (1622-1676), used the asterisk * in his work Teutsche Algebra (1659). As well as Leibniz, who previously used a fallen C, with the open side down, in his Dissertatio of combinatorial art (1666).

Answer 4

Circa 1950 Royal typerwriter. Top row of keys, second from the right. What do you see?

Answer 5

The asterisk was used in the 80s as a 'jolly' character for Operating System maintenance and procedures. I used the asterisk a lot when, under MS-DOS, I had to copy files or folders in particular ways. If I needed to copy only the .EXE files to a floppy disk, I'd write:

copy *.exe a:

The asterisk meant that 'all' files with an .exe extension had to be copied.

The asterisk was quite versatile! Say, for example, you wanted to copy to a floppy disk (or move, or delete) a group of files, but only those which name started with 1989_04, you could write:

copy 1989_04*.* a:

Meaning that any file starting with 1989_04 was going to be copied, and also with any extension (.*). So, if there were some .doc and some .xls, they'd be copied. If you wanted to specify only one type of extension, say .doc, then you'd write:

copy 1989_04*.doc a:

The asterisk was a much more powerful tool, these are just a few examples. Let me show you something that I still remember. Say you wanted to 'type' (list the file content on the screen) many files instead of only one at a time, you could write:

for %f in (*.*) do type %f

In this case, *.* means any file with any name (*) and any extension (.*). You could obviously replace partially or totally those 2 asterisks based on your needs.

If you open the old issues of PC Magazine that you have at home, some of which I'd love to buy, and you browse through the technical pages (usually located toward the end of the magazine and having paragraphs or tables with pink or green background), you'll find tons of other examples of commands, instructions, and codes using the asterisk. Sometimes you'll find them also in the section where the magazine staff answered readers' questions. I also added some additional examples of the use of the asterisk under MS-DOS and various info in the 'about me' section of my profile. I am basing my answer on MS-DOS because I know it, but I'm sure similar uses of the asterisk were occurring for other 80s operating systems.

In conclusion, in the 80s there were already countless uses for the asterisk in a large variety of contexts and situations, therefore, we should not be surprised if we found it on all types of keyboards.