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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

ENTER
 

you would actually type the letters m y f i l e and then press the 

ENTER
key.

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 

ALT
key on normal PC.

The 'Diamond' key is represented using the  symbol, also identified as the 

CTRL
key.

The cursor keys are represented as  and  key on normal PC.

 

We're currently working on this page, we hope to have it done soon.

 

The following operators may be used as part of expressions.

Arithmetic operators

The arithmetic operators take two numbers as operands.

+add -subtract
*multiply /divide
^raise to the power   

Relational operators

The relational operators can compare numbers, and return a logical value of FALSE=O and TRUE=-1.

less than =equal to
<=less than or equal to >greater than
<>not equal to >=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 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

0123456789101112
vec?0vec?11vec?2vec?3vec?4vec?5vec?6vec?7vec?8vec?9vec?10vec?11vec?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:

0123456789101112
vec?10vec?14vec?18vec?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:

0123456789101112
THE&20COMPUTER&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

Group 5

Group 6

Group 7

unary minus brackets

logical NOT

A    raise to the power

multiply divide

+    add subtract

less than

equal to

less than or equal to greater than

not equal to

greater than or equal to

AND Logical AND

OR    Logical OR

FOR Logical Exclusive-OR

 

NOT

so, for example, A-B*CAD is equivalent to A-(B*(CAD)).

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