Extra keys Although a computer keyboard typically contains between 80 and 110 keys, the computer itself can (and often does) use the equivalent of 256 different characters (2 to the8th power ... the why of thisparticular number will eventually be obvious). We therefore may need means of typing all these extra characters. Just as you use keys to change ordinary alphabetical keys between UPPER and lower case, the and keys are used to produce characters that are not normally on the keyboard. You can also produce any of the 256 computer char- acters by using the numeric keypad.
Shift Ctrl Alt Control key A control character is often indicated in computer manuals by preceding it with an up-arrow character, eg ^A is a control-A. This method is used in the Edit Quick Reference in Appendix A of the User Reference Manual , to save space. Normally however the Control key will be shown as . A control character is entered by holding down the key whilst typing and releasing the appropriate character, in this case an . It does not matter whether the character is in upper or lower case. The line editor uses many control keys. Ctrl Ctrl A Alt key Similarly, the symbol ( alternate A) indicates holding down the key then pressing . Several 1616 commands make use of the key.
Alt A Alt A Alt Esc key The notation indicates pressing the key labelled Esc , releasing it, and then pressing the next key required. The key precedes use of another key. It is not often used like a shift key. Esc Esc Number conventions A sign in front of a number indicates that the number is in base 16, or a hexadecimal number. However you do not type the sign when entering the number from the keyboard. Hexadecimal and binary numbers are explained in detail in many books on programming, and are traditionally used by programmers, mainlybecauseprogrammersfindthemeasierandmoreconvenientthan‘ordinary’ numbers. An ordinary decimal number is indicated by having a period ‘ .
’ placed in front of it. A binary number is indicated by a ‘ % ’ in front of it. Since it is more convenient (for programmers) to work in hexadecimal, all numbers entered into the 1616/OS areassumedtobehexadecimal,unlessyouindicateotherwise. Ifenteringadecimal number from the keyboard, you do so by placing a ‘ . ’ in front of it. Introduction User Tutorial Manual Page 11