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AR-B1474 User¡¦s Guide
4-5
4.3 WRITE PROTECT FUNCTION
The AR-B1474 provides hardware and software write protect functions for small page 5V FLASH disk and only
software write protected function for SRAM disk. This is to prevent your data on 5V FLASH or SRAM disk from
accidental deletion or overwrite. If your FLASH/SRAM disk is write protected, any write operation to the protected
FLASH/SRAM disk will get a write protect error:
Write protect error writing drive A
About, Retry, Fail?
4.3.1 Hardware Write Protect
To enable the hardware protect function for small page 5V FLASH disk, please set the SW1-5 to “ON” and the
SW1-6 to “ OFF” , please refer to the “Switch Setting” .
4.3.2 Software Write Protect
If you need the write protect function and sometimes you have to write or update data on your FLASH/SRAM disk,
you can use the software write protect instead of hardware write protect. The software write protect function is
enabled or disabled by writing a data to an I/O port.
4.3.3 Enable the Software Write Protect
Writes data 08h to the base port+2 address
Example 1: (in assembly language)
MOV DX, 212H ; If the AR-B1474’ s base I/O address is 210H
MOV AL, 08H ; Enable byte = 08h
OUT DX, AL
Example 2: (in BASICA language)
OUT &H212, &H08; REM If the AR-B1474’ s base I/O address is 210h
Example 3: (in Turbo C language)
outportb(0x212,0x08);/*If the AR-B1474’ s base I/O address is 210h*/
4.3.4 Disable the Software Write Protect
Writes data 0 to the base port+2 address
Example 1: (in assembly language)
MOV DX, 212H ; If the AR-B1474’ s base I/O address is 210h
MOV AL, 00H ; Disable byte=00h
OUT DX, AL
Example 2: (in BASICA language)
OUT &H212, &H00 ; REM If the AR-B1474’ s base I/O address is 210h
Example 3: (in Turbo C language)
outportb(0x212,0x00); /*If the AR-B1474’ s base I/O address is 210h*/