TAL Reference Manual

Data Representation
TAL Reference Manual—526371-001
3-5
Storage Units
Storage Units
Storage units are the containers in which you can access data stored in memory. The
system fetches and stores all data in 16-bit words, but you can access data as any of
the storage units listed in Table 3-2.
Address Modes
The data type of a variable determines byte or word addressing and indexing, as
discussed elsewhere in this manual and in the TAL Programmer’s Guide.
Operations by Data Type
The data type of a variable determines the operations you can perform on the variable.
Table 3-3
lists the operations by data type.
Table 3-2. Storage Units
Storage Unit
Number of
Bits Data Type Description
Byte 8 STRING One of two bytes that make up a
word
Word * 16 INT Two bytes, with byte 0 (most
significant) on the left and byte 1
(least significant) on the right
Doubleword 32 INT (32),
REAL
Two contiguous words
Quadrupleword 64 REAL (64),
FIXED
Four contiguous words
Bit field 1-16 UNSIGNED Contiguous bit fields within a word
Bit field 17-31 UNSIGNED Contiguous bit fields within a
doubleword
* In TAL a word is always 16 bits regardless of the word size used by the system hardware.
Table 3-3. Operations by Data Type (page 1 of 2)
Operation STRING
INT or
Unsigned
(1-16)
INT (32) or
Unsigned
(17-31) FIXED
REAL or
REAL (64)
Unsigned
arithmetic
Yes Yes No No No
Signed
arithmetic
Yes Yes Yes Yes Yes
Logical
operations
Yes Yes No No No