Z8932120FSC ZILOG [Zilog, Inc.], Z8932120FSC Datasheet - Page 35

• Manufacturer Part Number: Z8932120FSC
• Description: 16-BIT DIGITAL SIGNAL PROCESSORS
• Manufacturer: ZILOG [Zilog, Inc.]

Zilog
There are eight distinct addressing modes for data trans-
fer.
<pregs>, <hwregs> These two modes are used for sim-
ple loads to and from registers within the chip, such as
loading to the Accumulator, or loading from a pointer reg-
ister. The names of the registers need only be specified in
the operand field (destination first, then source).
<regind> This mode is used for indirect accesses to the
data RAM. The address of the RAM location is stored in
the pointer. The Ò@Ó symbol indicates ÒindirectÓ and pre-
cedes the pointer, therefore @P1:1 instructs the processor
to read or write to a location in RAM1, which is specified by
the value in the pointer.
<dregs> This mode is also used for accesses to the data
RAM, but only the lower 16 addresses in either bank. The
4-bit address comes from the status register and the oper-
and field of the data pointer. Note that data registers are
typically used not for addressing RAM, but loading data
from program memory space.
<memind> This mode is used for indirect accesses to the
program memory. The address of the memory is located in
a RAM location, which is specified by the value in a point-
er. Therefore, @@P1:1 instructs the processor to read
(write is not possible) from a location in memory, which is
CONDITION CODES
The following Instruction Description defines the condition
codes supported by the DSP assembler.
Code
C
EQ
F
IE
MI
NC
NE
NIE
NOV
NU0
DS97DSP0100
Description
Carry
Equal (same as Z)
False
Interrupts Enabled
Minus
No Carry
Not Equal (same as NZ)
Not Interrupts Enabled
Not Overßow
Not User Zero
P R E L I M I N A R Y
specified by a value in RAM, and the location of the RAM
is in turn specified by the value in the pointer. Note that the
data pointer can also be used for a memory access in this
manner, but only one Ò@Ó precedes the pointer. In both
cases, the memory address stored in RAM is incremented
by one, each time the addressing mode is used, to allow
easy transfer of sequential data from program memory.
<accind> Similar to the previous mode, the address for
the program memory read is stored in the Accumulator.
@A in the second operand field loads the number in mem-
ory specified by the address in A.
<direct> The direct mode allows read or write to data
RAM from the Accumulator by specifying the absolute ad-
dress of the RAM in the operand of the instruction. A num-
ber between 0 and 255 indicates a location in RAM0, and
a number between 256 and 511 indicates a location in
RAM1.
<limm> This address mode indicates a long immediate
load. A 16-bit word can be copied directly from the operand
into the specified register or memory.
<simm> This address mode can only be used for imme-
diate transfer of 8-bit data in the operand to the specified
RAM pointer.
If the instruction description refers to the <cc> (condition
code) symbol in one of its addressing modes, the instruc-
tion will only execute if the condition is true.
Code
NU1
NZ
OV
PL
U0
U1
UGE
ULT
Z
Description
Not User One
Not zero
Overßow
Plus (Positive)
User Zero
User One
Unsigned Greater Than or
Equal (Same as NC)
Unsigned Less Than (Same as C)
Zero
16-Bit Digital Signal Processors
Z89321/371/391
35
1