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CHAPTER 20 1M-BIT (128KB) FLASH MEMORY
20.1 Overview of the 1M-Bit Flash Memory
he 1M-bit flash memory is mapped to the FC to FF banks in the CPU memory map. The
functions of the flash memory interface circuit enable read-access and program-
access from the CPU in the same way as mask ROM. Instructions from the CPU can
be used via the flash memory interface circuit to write data to and erase data from the
flash memory. Internal CPU control therefore enables rewriting of the flash memory
while it is mounted. As a result, improvements in programs and data can be
performed efficiently.
However, no selector operation such as the enable sector protect can be used.
s Characteristics of the 1M-Bit Flash Memory
Sectors of 128K words x 8/32K words x 16 bits (16K+8K+8K+32K+64K)
Use of automatic program algorithm (Embedded Algorithm: Equivalent to MBM29F400TA)
Erase pause/restart function provided
Detection of completion of writing/erasing using data polling or toggle bit functions
Detection of completion of writing/erasing using CPU interrupts
Compatibility with the JEDEC standard-type command
Sector erase function (any combination of sectors)
Minimum of 10,000 write/erase operations
"Embedded Algorithm" is the trademark of Advanced Micro Device.
s Writing to/Erasing Flash Memory
The flash memory cannot be written to and read at the same time. That is, when data is written
to or erased from the flash memory, the program in the flash memory must first be copied to
RAM. The entire process is then executed in RAM so that data is simply written to the flash
memory. This eliminates the need for the program to access the flash memory from the flash
memory itself.