SNR008

8M-bit Mask ROM

4. Memory mapping for AD Bus Interface

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

between SNC710 and SNR008 are through data bus D[0..7]. SNC710 allows user to

connect maximum 2 external mask ROM, and SNR008 has 5 bank select pins

(BS0~BS4) to specify the memory region of each mask ROM.

BS4~BS0

Address Region

BS4~BS0

Address Region

00100

0x0200000 ~ 0x027FFFF

10010

0x0900000 ~ 0x097FFFF

00101

0x0280000 ~ 0x02FFFFF

10011

0x0980000 ~ 0x09FFFFF

00110

0x0300000 ~ 0x037FFFF

10100

0x0A00000 ~ 0x0A7FFFF

00111

0x0380000 ~ 0x03FFFFF

10101

0x0A80000 ~ 0x0AFFFFF

01000

0x0400000 ~ 0x047FFFF

10110

0x0B00000 ~ 0x0B7FFFF

01001

0x0480000 ~ 0x04FFFFF

10111

0x0B80000 ~ 0x0BFFFFF

01010

0x0500000 ~ 0x057FFFF

11000

0x0C00000 ~ 0x0C7FFFF

01011

0x0580000 ~ 0x05FFFFF

11001

0x0C80000 ~ 0x0CFFFFF

01100

0x0600000 ~ 0x067FFFF

11010

0x0D00000 ~ 0x0D7FFFF

01101

0x0680000 ~ 0x06FFFFF

11011

0x0D80000 ~ 0x0DFFFFF

01110

0x0700000 ~ 0x077FFFF

11100

0x0E00000 ~ 0x0E7FFFF

01111

0x0780000 ~ 0x07FFFFF

11101

0x0E80000 ~ 0x0EFFFFF

10000

0x0800000 ~ 0x087FFFF

11110

0x0F00000 ~ 0x0F7FFFF

10001

0x0880000 ~ 0x08FFFFF

11111

0x0F80000 ~ 0x0FFFFFF

Table-1

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

of bank select pins BS4~BS0 CAN’T be the range 0000~0x0011.

Ver. 1.3

August 29, 2003

4