IS89C52 View Datasheet(PDF) - Integrated Silicon Solution

Part Name

Description

Manufacturer

IS89C52

CMOS SINGLE CHIP 8-BIT MICROCONTROLLER with 8-Kbytes of FLASH

Integrated Silicon Solution 

IS89C52

ISSI ®

OPERATING DESCRIPTION

The detail description of the IS89C52 included in this

description are:

• Memory Map and Registers

• Timer/Counters

• Serial Interface

• Interrupt System

• Other Information

• Flash Memory

MEMORY MAP AND REGISTERS

Memory

The IS89C52 has separate address spaces for program

and data memory. The program and data memory can be

up to 64K bytes long. The lower 8K program memory can

reside on-chip. Figure 5 shows a map of the IS89C52

program and data memory.

The IS89C52 has 256 bytes of on-chip RAM, plus numbers

of special function registers. The lower 128 bytes can be

accessed either by direct addressing or by indirect

addressing. Figure 6 shows internal data memory

organization and SFR Memory Map.

The lower 128 bytes of RAM can be divided into three

segments as listed below and shown in Figure 7.

1. Register Banks 0-3: locations 00H through 1FH (32

bytes). The device after reset defaults to register bank

0. To use the other register banks, the user must select

them in software. Each register bank contains eight

1-byte registers R0-R7. Reset initializes the stack

point to location 07H, and is incremented once to start

from 08H, which is the first register of the second

register bank.

2. Bit Addressable Area: 16 bytes have been assigned

for this segment 20H-2FH. Each one of the 128 bits of

this segment can be directly addressed (0-7FH). Each

of the 16 bytes in this segment can also be addressed

as a byte.

3. Scratch Pad Area: 30H-7FH are available to the user

as data RAM. However, if the data pointer has been

initialized to this area, enough bytes should be left

aside to prevent SP data destruction.

Program Memory

(Read Only)

FFFFH:

64K

Data Memory

(Read/Write)

FFFFH:

External

EA = 0

External

1FFFH:

8K

0000

EA = 1

Internal

PSEN

Internal

FFH:

00

0000

RD WR

Figure 5. IS89C52 Program and Data Memory Structure

Integrated Silicon Solution, Inc. — 1-800-379-4774

7

MC013-1C

11/21/98

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