Acrosser Technology AR-B1380, User Manual

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AR-B1380/AR-B1380A User’ s Guide
Page 73
TI TMS27C040 (512Kx8, 4M bits)
TOSHIBA TCS714000 (512Kx8, 4M bits)
ATMEL AT27C080 (1Mx8, 8M bits)
9. USING MEMORY BANKS
This appendix provides the information about how to access the memory on the AR-B1380/AR-B1380A
without using the AR-B1380/AR-B1380A SSD BIOS. The AR-B1380/AR-B1380A hardware divides every
8K bytes of memory into a memory bank. To access the data in the memory, you have to assign the chip
number and the bank number. On every chip, the memory bank number starts from zero. The last memory
bank number depends on the size of the memory chip used on the AR-B1380/AR-B1380A. For example, if
you use the 256K bytes memory chip, the bank number on every chip would be in the range of 0 to 31. The
chip numbers and the bank numbers are determined by the bank select register on the AR-B1380/AR-
B1380A.
The I/O address of these registers are determined by SW2-1/SW2-2
. The memory address of the memory bank is located on the range selected by SW2-3/SW2-4.
The I/O port address of the bank select register is base port+0, and the I/O port address of the chip select
register is base port +2. The following is the format of the bank select register and bank enable register.
Register I/O Port D7 D6 D5 D4 D3 D2 D1 D0
Bank Select Register Base +0 WPE A6 A5 A4 A3 A2 A1 A0
Chip Select Register Base +2 0 0 0 1 CS1 CS0 X X
Where:
WPE Write protect enable bit
A6~A0 Bank select bits, A0 is the LSB
CS1~CS0 Chip select bits of MEM1 to MEM3
Where:
CS1-CS0 : Chip select
CS1 CS0 Socket
0 0 Disable
0 1 MEM1
1 0 MEM2
1 1 MEM3
For different types of memory, A0 to A6 have different explanations. These bits are used to select the bank
number of specific memory located in CS0 and CS1.
Memory A6 A5 A4 A3 A2 A1 A0
64KB EPROM (FLASH)
0
0 1 0 BS2 BS1 BS0
128KB EPROM (FLASH)
0
0 0 BS3 BS2 BS1 BS0
256KB EPROM (FLASH) 0 BS4 1 BS3 BS2 BS1 BS0
512KB EPROM (FLASH)
0
BS4 BS5 BS3 BS2 BS1 BS0
1MB EPROM (FLASH)
BS6
BS4 BS5 BS3 BS2 BS1 BS0
128KB SRAM 0 1 0 BS3 BS2 BS1 BS0
512KB SRAM
0
BS5 BS4 BS3 BS2 BS1 BS0
NOTE : BS0 to BS5 are the memory bank select bits. For example, 128KB memory has sixteen 8K-byte
banks, so 4 bits (BS0 to BS3) are needed.