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In this manual, anything displayed on the Cambridge Z88 screen is shown in a computer typeface, such as
Name of file to save
Anything that you should type at the keyboard is shown in a different typeface to designate the keyboard keys; for example
You are invited to a party
The keys on the keyboard with a special function are shown in the text with key legends. So, for example, if you are asked to type
myfile
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ENTER |
you would actually type the letters m y f i l e and then press the
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ENTER |
In general, references to menu headings are in bold caps; for example LAYOUT.
References to individual commands are in bold; for example Save or Load.
References to options displayed by a command are in italics; for example Save only range of columns.
The 'Square' key is represented using the symbol, also identified as the
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| ALT |
The 'Diamond' key is represented using the symbol, also identified as the
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CTRL |
The cursor keys are represented as ,
,
and
key on normal PC.
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We're currently working on this page, we hope to have it done soon. |
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The following operators may be used as part of expressions.
Arithmetic operators
The arithmetic operators take two numbers as operands.
| + | add | - | subtract | |
| * | multiply |
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| / | divide | ||
| ^ | raise to the power |
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Relational operators
The relational operators can compare numbers, and return a logical value of FALSE=O and TRUE=-1.< less
| < | less than | = | equal to | |
| <= | less than or equal to | > | greater than | |
| <> | not equal to |
Logical operatorsequal to
> greater than
| >= | greater than or equal to |
Logical operators
The logical operators operate on numeric or logical values. Boolean FALSE is taken as zero, TRUE as —1.
Indirection operators
The following operators allow the programmer to access memory directly (called PEEK in other versions of BASIC) or to alter the contents of specified memory locations (called POKE in other BASICs).
These operators should only be used by experienced programmers, since they give the programmer the capability of altering the operation of other activities in the Cambridge Z88 operating system; in general, only addresses within the region allocated by a BASIC DIM statement should be altered.
| ? | byte |
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| indirection | ! | word indirection | ||
| $ | string indirection |
The usual way of using these operators is to allocate a vector using the DIM statement, and then manipulate elements of this vector with the indirection operators. For example,
DIM vec 15
allocates a vector of 16 bytes, and assigns its address to the variable vec. These bytes can be addressed as
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| vec?0 | vec?11 | vec?2 | vec?3 | vec?4 | vec?5 | vec?6 | vec?7 | vec?8 | vec?9 | vec?10 | vec?11 | vec?12 |
Note that ?vec is an alternative way of writing vec ? 0. A typical manipulation might be
vec?l = vec?l + 1
Alternatively the vector could be addressed as 4 four-byte words:
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| vec?10 | vec?14 | vec?18 | vec?12 | |||||||||
Finally, the string indirection operator allows a string to be stored directly into an area of memory. For example:
$vec = "THE COMPUTER"
stores characters in the vector as follows:
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| T | H | E | &20 | C | O | M | P | U | T | E | R | &0D |
| $vec |
The string can be accessed with the $ operator, so the following statement will print the string:
PRINT $vec
Individual characters can be accessed with the ? operator.
Order of precedence
The order of precedence of the operators is as follows:
Group 1
Group 2
Group 3
Group 4
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