Z8932120PSC Datasheet, PDF (35/40 Pages) Zilog, Inc. – 16-BIT DIGITAL SIGNAL PROCESSORS

Zilog
Z89321/371/391
16-Bit Digital Signal Processors
There are eight distinct addressing modes for data trans- specified by a value in RAM, and the location of the RAM
fer.
is in turn specified by the value in the pointer. Note that the
1 ^{data pointer can also be used for a memory access in this}
<pregs>, <hwregs> These two modes are used for sim- _{manner, but only one Ò@Ó precedes the pointer. In both}
ple loads to and from registers within the chip, such as _{cases, the memory address stored in RAM is incremented}
loading to the Accumulator, or loading from a pointer reg- _{by one, each time the addressing mode is used, to allow}
ister. The names of the registers need only be specified in _{easy transfer of sequential data from program memory.}
the operand field (destination first, then source).
<accind> Similar to the previous mode, the address for
<regind> This mode is used for indirect accesses to the _{the program memory read is stored in the Accumulator.}
data RAM. The address of the RAM location is stored in _{@A in the second operand field loads the number in mem-}
the pointer. The Ò@Ó symbol indicates ÒindirectÓ and pre- _{ory specified by the address in A.}
cedes the pointer, therefore @P1:1 instructs the processor
to read or write to a location in RAM1, which is specified by <direct> The direct mode allows read or write to data
the value in the pointer.
RAM from the Accumulator by specifying the absolute ad-
dress of the RAM in the operand of the instruction. A num-
<dregs> This mode is also used for accesses to the data _{ber between 0 and 255 indicates a location in RAM0, and}
RAM, but only the lower 16 addresses in either bank. The _{a number between 256 and 511 indicates a location in}
4-bit address comes from the status register and the oper- _RAM1.
and field of the data pointer. Note that data registers are
typically used not for addressing RAM, but loading data <limm> This address mode indicates a long immediate
from program memory space.
load. A 16-bit word can be copied directly from the operand
into the specified register or memory.
<memind> This mode is used for indirect accesses to the
program memory. The address of the memory is located in <simm> This address mode can only be used for imme-
a RAM location, which is specified by the value in a point- diate transfer of 8-bit data in the operand to the specified
er. Therefore, @@P1:1 instructs the processor to read RAM pointer.
(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
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
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
DS97DSP0100
PRELIMINARY
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