Z89C00 View Datasheet(PDF) - Zilog
Part Name
Description
Manufacturer
Z89C00 Datasheet PDF : 28 Pages
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ZILOG
REGISTERS
PRELIMINARY
Z89C00
16-BIT DIGITAL SIGNAL PROCESSOR
There are 12 internal registers which are defined below:
Register
P
X
Y
A
SR
Pn:b
PC
Register Definition
Output of Multiplier, 24-bit, Read Only
X Multiplier Input, 16-bit
Y Multiplier Input, 16-bit
Accumulator, 24-bit
Status Register, 16-bit
Six Ram Address Pointers, 8-bit Each
Program Counter, 16-bit
The following are virtual registers as physical RAM does
not exist on the chip.
Register
EXTn
BUS
Dn:b
Register Definition
External registers, 16-bit
D-Bus
Eight Data Pointers
P holds the result of multiplications and is read only.
X and Y are two 16-bit input registers for the multiplier.
These registers can be utilized as temporary registers
when the multiplier is not being used. The contents of the
P register will change if X or Y is changed.
Pn:b are the pointer registers for accessing data RAM.
(n = 0,1,2 refer to the pointer number) (b = 0,1 refers to
RAM bank 0 or 1). They can be directly read from or written
to, and can point to locations in data RAM or indirectly to
Program Memory.
EXT(n) are external registers (n = 0 to 7). There are eight
16-bit registers here for accessing External data,
peripherals, or memory. Note that the actual register RAM
does not exist on the chip, but would exist as part of the
external device such as an ADC result latch.
BUS is a read-only register which, when accessed, returns
the contents of the D-Bus.
Dn:b refer to possible locations in RAM that can be used
as a pointer to locations in program memory. The
programmer decides which location to choose from two
bits in the status register and two bits in the operand. Thus,
only the lower 16 possible locations in RAM can be
specified. At any one time there are eight usable pointers,
four per bank, and the four pointers are in consecutive
locations in RAM. For example, if S3/S4 = 01 in the status
register, then D0:0/D1:0/D2:0/D3:0 refer to locations
4/5/6/7 in RAM bank 0. Note that when the data pointers are
being written to, a number is actually being loaded to Data
RAM, so they can be used as a limited method for writing
to RAM.
A is a 24-bit Accumulator. The output of the ALU is sent to
this register. When 16-bit data is transferred into this
register, it goes into the 16 MSB’s and the least significant
eight bits are set to zero. Only the upper 16 bits are
transferred to the destination register when the Accumulator
is selected as a source register in transfer instructions.
DC 4083-00
7
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