Page 35 of 62
SBasic User's Manual SBasic Version 2.7 Page 35
Printed: December 5, 1999
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| | = LROLL() | | = RROLL()
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The PEEK function returns the 16-bit value stored in a specific
address. This is the usual function for reading 16-bit I/O ports.
Example:
a = peek($1000) ' get 16-bit value from address $1000
You can make your use of PEEK easier to understand if you combine it
with named constants defined with the CONST statement.
Example:
const porta = $1000 ' define address of port A
a = peek(porta) ' get 16-bit value at port A
The PEEKB function returns the 8-bit value stored in a specific
address. This is the usual function for reading 8-bit I/O ports.
Example:
a = peekb($1020) ' get 8-bit value from address $1020
Recall that the = (assignment) operator writes a 16-bit value to a
variable. In the case of the PEEKB function, the top eight bits of
the variable will always be written as 0. Thus, reading a value of
$45 in the above example results in storing $0045 in variable A.
You can make your use of PEEKB easier to understand if you combine it
with named constants defined with the CONST statement.
Example:
const portb = $1020 ' define address of port B
a = peekb(portb) ' get 8-bit value at port B
The POKE statement writes a 16-bit value to a specific address. This
is the usual statement for writing data to 16-bit I/O ports.
Example:
poke $1000, a ' write value in A to address $1000
Note the difference in syntax between the PEEK function and the POKE
statement; PEEK uses parentheses around the address argument, while
POKE does not use parentheses.