Z8937116FSC datasheet(18/40 Pages) ZILOG

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Z89321/371/391

16-Bit Digital Signal Processors

Zilog

P R E L I M I N A R Y

DS97DSP0100

ADDRESS SPACE

Program Memory. Programs of up to 4 K words can be

masked into internal ROM (OTP for Z89371). Four loca-

tions are dedicated to the vector address for the three in-

terrupts (0FFDH-0FFFH) and the starting address follow-

ing a Reset (0FFCH). Internal ROM is mapped from 0000H

to 0FFFH, and the highest location for program is 0FFBH.

A 64 K word External Program Memory Space is available

on the Z89391. The vector addresses for the Z89391 re-

side at FFFCH-FFFFH (Figure 15).

Internal Data RAM. The Z89321, 371 and 391 all have in-

ternal 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 address-

es 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 per-

form 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 ad-

dress 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 Z89321 has 19 internal registers and up to

an additional eight external registers. The external regis-

ters are user-definable for peripherals, such as A/D or D/A,

or to DMA, or other addressing peripherals. Both external

and internal registers are accessed in one machine cycle.

Figure 14. External Program Memory Port Timing

TCY

PDSET

PDHOLD

Valid

PASET

CLOCK

PROGRAM

ADDRESS

PROGRAM

DATA

Figure 15. Memory Map

Data Memory

Not Used

DRAM1

DRAM0

01FF

0100

00FF

0000

FFFF

Program Memory

Not Used

INT0-INT2 Vect.

RESET Vector

0FFF

0FFC

0000

FFFF

FFFC

4 Kwords

INT0-INT2 Vect.

RESET Vector

64 Kwords

512 words

On-Chip Memory

Off-Chip Memory

Z8937116FSC Datasheet(PDF) 18 Page - Zilog, Inc.

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