Z86C9620VSC datasheet(19/46 Pages) ZILOG

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Z86C61/62/96

Z8® MICROCONTROLLER

FUNCTIONAL DESCRIPTION

Address Space

Program Memory. The Z86C61/62 can address up to 48

Kbytes of external program memory (Figure 16). The first

12 bytes of program memory are reserved for the interrupt

vectors. These locations contain six 16-bit vectors that

correspond to the six available interrupts. For ROM mode,

byte 13 to byte 16383 consists of on-chip ROM. At ad-

dresses 16384 and greater, the Z86C61/62 executes

external program memory fetches. The Z86C96, and the

Z86C61/62 in ROMless mode, can address up to 64

Kbytes of external program memory. Program execution

begins at external location 000CH after a reset.

Data Memory (/DM). The ROM version can address up to

48 Kbytes of external data memory space beginning at

location 16384. The ROMless version can address up to 64

Kbytes of external data memory. External data memory

may be included with, or separated from, the external

program memory space. /DM, an optional I/O function that

can be programmed to appear on pin P34, is used to

distinguish between data and program memory space

(Figure 17). The state of the /DM signal is controlled by the

type instruction being executed. An LDC opcode refer-

ences PROGRAM (/DM inactive) memory, and an LDE

instruction references DATA (/DM active Low) memory.

External

ROM and RAM

Location of

First Byte of

Instruction

Executed

After RESET

Interrupt

Vector

(Lower Byte)

Interrupt

Vector

(Upper Byte)

IRQ5

IRQ4

IRQ3

IRQ2

IRQ1

IRQ0

IRQ5

65535

On-Chip ROM

16384

16383

Figure 16. Program Memory Configuration

65535

16384

16383

External

Data

Memory

Not Addressable

Figure 17. Data Memory Configuration

Z86C9620VSC Datasheet(PDF) 19 Page - Zilog, Inc.

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