Motorola M68000 Betriebsanweisung PDF herunterladen (Seite 49)

Assembler Source Format 35

we can use are:

Indicator Base

% 2

@ 8

[none] 10

$ 16

A binary constant would naturally consist of a percent sign followed

by only l’s and 0’s. If we try to write a binary constant with other than

l’s and 0’s, it is an error. The following are all valid constants:

1234 1234,0

$1234 1234,6

$1100111001 11001110012

$FFFF FFFF,e

@377 3778

Character string constants are ASCII character strings delimited by

apostrophes. A character string constant must appear entirely on one line.

Any valid “printing” characters from the ASCII character set are allowed.

For example,

'Hello there.'

is a character string of length 12. The two apostrophes are not part of the

string. What do we do if we want an apostrophe? We can’t just place one

in the middle of the string, that would terminate the string. If we want a

single apostrophe, we merely write two apostrophes. For example,

'Don''t give up the ship.'

is actually the string “Don’t give up the ship.”.

If a string is one to four characters long it can be used as a numeric

value. In this case, the characters are right-justified. This means that the

ASCII values of the characters are used as the low-order bytes. Any

high-order bytes that do not have a corresponding character are filled

with zeros. If it is longer than four characters, it is merely the string

of bytes with the appropriate ASCII values. Both upper and lower case

characters can be used in character strings.

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Motorola M68000 Betriebsanweisung Seite 49