Z89323 Datasheet, PDF (12/61 Pages) Zilog, Inc. – 16-BIT DIGITAL SIGNAL PROCESSORS

PIN FUNCTIONS (Continued)
PRELIMINARY
Z89323/373/393
16-BIT DIGITAL SIGNAL PROCESSORS
VAHI and VALO. Analog to Digital reference voltages.
/PAZ Tri-state Program Bus. This pin enables the Program
Address bus for emulation purposes.
/EXTEN Ext Enable. This pin enables Ext output
continuously for emulation purposes.
/ROMEN ROM Enable. This pin selects internal or external
Program Memory.
ADDRESS SPACE
Program Memory. Programs of up to 8 Kwords can be
masked into internal ROM (OTP for Z89373). Four locations
are dedicated to the vector address for the three interrupts
(IFFDH-IFFFH) and the starting address following a Reset
(IFFCH). Internal ROM is mapped from 0000H to IFFFH,
and the highest location for program is IFFBH.
Internal Data RAM. The Z89323 has an internal 512 x 16-
bit word data RAM organized as two banks of 256 x 16-bit
words each: RAM0 and RAM1. Each data RAM bank is
addressed by three pointers: Pn:0 (n = 0-2) for RAM0 and
Pn:1 (n = 0-2) for RAM1. The RAM addresses for RAM0 and
RAM1 are arranged from 0-255 and 256-511, respectively.
The address pointers, which may be written to, or read
from, are 8-bit registers connected to the lower byte of the
internal 16-bit D-Bus and are used to perform modulo
addressing. Three addressing modes are available to
access the Data RAM: register indirect, direct addressing,
and short form direct. The contents of the RAM can be read
to, or written from, in one machine cycle per word, without
disturbing any internal registers or status other than the
RAM address pointer used for each RAM. The contents of
each RAM can be loaded simultaneously into the X and Y
inputs of the multiplier.
Registers. The Z89323 has 19 internal registers and eight
external registers and a secondary set of 15 peripheral
control registers. Both external and internal registers are
accessed in one machine cycle. The external registers are
used to access the on-chip peripherals when they are
enabled.
Data Memory
FFFF
Not Used
Program Memory
FFFF
FFFC
INT0-INT2 Vect.
RESET Vector
64 Kwords
Not Used
Or
512 words
DRAM1
DRAM0
01FF 4 Kwords
0100
00FF
0000
INT0-INT2 Vect. 0FFF
RESET Vector 0FFC
0000
On-Chip Memory
(Z89323/371)
Off-Chip Memory
(Z89393)
Figure 6. Memory Map
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DS95DSP0101 Q4/95