The System Variables of the Sinclair ZX81 The bytes in memory from 16384 to 16508 are set aside for specific uses by the system. You can peek them to find out various things about the system, and some of them can be usefully poked. They are listed here with their uses. These are called system variables and carry names, but do not confuse them with the variables used by the BASIC. You cannot use the names in a BASIC program; they are simply mnemonics that are used to make it easier to refer to the variables. The abbreviations in column 1 have the following meanings. X The variable should not be poked, because the system might crash. N Poking the variable will have no lasting effect. S The variable is saved by SAVE.

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