cop8ccr9 National Semiconductor Corporation, cop8ccr9 Datasheet - Page 22

• Manufacturer Part Number: cop8ccr9
• Description: 8-bit Cmos Flash Microcontroller With 32k Memory, Virtual Eeprom, 10-bit A/d And Brownout
• Manufacturer: National Semiconductor Corporation

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10.0 Functional Description
10.4.1 Virtual EEPROM
The Flash memory and the User ISP functions (see Section
5.7), provide the user with the capability to use the flash
program memory to back up user defined sections of RAM.
This effectively provides the user with the same nonvolatile
data storage as EEPROM. Management, and even the
amount of memory used, are the responsibility of the user,
however the flash memory read and write functions have
been provided in the boot ROM.
One typical method of using the Virtual EEPROM feature
would be for the user to copy the data to RAM during system
initialization, periodically, and if necessary, erase the page of
Flash and copy the contents of the RAM back to the Flash.
FIGURE 7. RAM Organization
(Continued)
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10.5 OPTION REGISTER
The Option register, located at address 0x7FFF in the Flash
Program Memory, is used to configure the user selectable
security, WATCHDOG, and HALT options. The register can
be programmed only in external Flash Memory programming
or ISP Programming modes. Therefore, the register must be
programmed at the same time as the program memory. The
contents of the Option register shipped from the factory read
00 Hex.
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