SNR032

32M-bit Mask ROM

4.

BUS INTERFACE

SNR032 provides three different bus modes to connect to host CPU, AD-bus mode,

byte mode and word mode. And the switching between different modes is depended

on the pin option “TYPE” and “MODE”. The following table is shown the relation ship of

“TYPE”, “MODE” pins and mode switching.

Mode

TYPE pin

MODE pin

AD-Bus Interface

VDD

Don’t care

Byte Mode Interface

GND

GND

Word Mode Interface

GND

VDD

4.1

AD-Bus Interface

For 8-bit AD (address/data) bus interface, all the address and data communication

between SNC710 and SNR032 are through data bus D[0..7]. SNC710 allows user to

connect maximum 2 external mask ROM. The option pin “TYPE” must connected to

VDD then the AD-bus interface to be enable. In AD-Bus mode, SNR032 has three

bank select pins BS2~BS4 to specify the memory region of SNR032. The address

region setting of SNR032 is shown as bellow.

BS4~BS2

Address Region

001

0x0200000 ~ 0x03FFFFF

010

0x0400000 ~ 0x05FFFFF

011

0x0600000 ~ 0x07FFFFF

100

0x0800000 ~ 0x09FFFFF

101

0x0A00000 ~ 0x0BFFFFF

110

0x0C00000 ~ 0x0DFFFFF

111

0x0E00000 ~ 0x0FFFFFF

Table-1

Note: For the address region 0x00000~0x01FFFFF are reserved, so the setting

of bank select pins BS4~BS2 CAN’T be the range 0000~0x0011.

Ver. 1.2

October 21, 2005

4