Sony AR-B1474, DX4, 486DX Memory Banks & Programming RS-485, Using Memory Bank, CS1 CS0, Socket

AR-B1474 User¡¦s Guide

9.MEMORY BANKS & PROGRAMMING RS-485

9.1 USING MEMORY BANK

This section provides the information about how to access the memory on the AR-B1474 without using the AR- B1474 SSD BIOS. The AR-B1474 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- B1474. 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- B1474.

The I/O addresses of these registers are determined by SW1-1and SW1-2. The memory address of the memory bank is located on the range selected by SW1-3 and SW1-4.

The I/O port address of the bank select register is base port+0. The following is the format of the bank select register and bank enable register.

BASE+0

	D7	D6	D5	D4		D3	D2	D1	D0
	CS1	CS0	K5	K4		K3	K2	K1	K0
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, K0 to K5 have different explanations. These bits are used to select the bank number of specific memory located in CS0 and CS1.

Memory	K5	K4	K3	K2	K1	K0
64KB EPROM (FLASH)	0	1	0	BS2	BS1	BS0
128KB EPROM (FLASH)	0	1	BS3	BS2	BS1	BS0
256KB EPROM (FLASH)	BS4	1	BS3	BS2	BS1	BS0
512KB EPROM (FLASH)	BS4	BS5	BS3	BS2	BS1	BS0
128KB SRAM	1	0	BS3	BS2	BS1	BS0
512KB SRAM	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, and 512KB memory needs 6 bits (BS0 to BS5), etc.

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