Zilog Z80380 - Manual (Page 34)

4-9
Z380 ™
U SER ' S M ANUAL Z ILOG
DC-8297-03
4.3 DATA TYPES
The Z380 CPU can operate on bits, binary-coded decimal
(BCD) digits (four bits), bytes (eight bits), words (16 bits or
32 bits), byte strings, and word strings. Bits in registers can
be set, cleared, and tested.
The basic data type is a byte, which is also the basic
accessible element in the register, memory, and I/O address
space. The 8-bit load, arithmetic, logical, shift, and rotate
instructions operate on bytes in registers or memory. Bytes
can be treated as logical, signed numeric, or unsigned
numeric value.
Words are operated on in a similar manner by the word
load, arithmetic, logical, and shift and rotate instructions.
Operation on 2-byte words is also supported. Sixteen-bit
load and arithmetic instructions operate on words in
registers or memory; words can be treated as signed or
unsigned numeric values. I/O reads and writes can be
8-bit or 16-bit operations. Also, the Z380 CPU architecture
supports operation in Long Word mode to handle a 32-bit
address manipulation. For that purpose, 16-bit wide
registers originally on the Z80 have been expanded to 32
bits wide, along with the support of the arithmetic instruction
needed for a 32-bit address manipulation.
Bits are fully supported and addressed by number within
a byte (see Figure 2-2). Bits within byte registers or
memory locations can be tested, set, or cleared.
Operation on binary-coded decimal (BCD) digits are sup-
ported by Decimal Adjust Accumulator (DAA) and Rotate
Digit (RLD and RRD) instructions. BCD digits are stored in
byte registers or memory locations, two per byte. The DAA
instruction is used after a binary addition or subtraction of
BCD numbers. Rotate Digit instructions are used to shift
BCD digit strings in memory.
Strings of up to 65536 (64K) bytes of Byte data or Word
data can be manipulated by the Z380 CPU’s block move,
block search, and block I/O instructions. The block move
instructions allow strings of bytes/words in memory to be
moved from one location to another. Block search instruc-
tions provide for scanning strings of bytes/words in memory
to locate a particular value. Block I/O instructions allow
strings of bytes or words to be transferred between memory
and a peripheral device.
Arrays are supported by Indexed mode (with 8-bit, 16-bit,
or 24-bit displacement). Stack is supported by the Indexed
and the Stack Pointer Relative addressing modes, and by
special instructions such as Call, Return, Push, and Pop.
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the customer and Zilog prior to use. Life support devices or
systems are those which are intended for surgical implantation
into the body, or which sustains life whose failure to perform,
when properly used in accordance with instructions for use
provided in the labeling, can be reasonably expected to result in
significant injury to the user.
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