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Chapter 14 Automatic Transfer Controller
XIV - 11
13
14-3-2 Setting the Memory Address
Setting the transfer addresses to the memory pointers
The address of the memory space for an automatically data transfer of ATC1 should be set in the both of
memory pointer 0 (AT1MAP0) and memory pointer 1 (AT1MAP1). In each transfer mode, one of those
pointer is the source address, and another is the destination address.
Memory pointer 0 functions
Memory pointer 0 is comprised of three 8-bit registers, AT1MAP0H, AT1MAP0M, and AT1MAP0L.
AT1MAP0H holds upper 2bits of the 18-bit address, AT1MAP0M contains the middle 8 bits, and
AT1MAP0L contains lower 8 bits. The 18-bit address set in memory pointer 0 points to a specific address
in the total memory space of 256 KB.
Memory pointer 0 also contains a computational function that enables it to increment the address based
on the transfer state. You can disable this function for all transfer modes by setting the FMODE bit of
ATC1 control register 0 to "1".
Memory pointer 1 functions
Memory pointer 1 is comprised of three 8-bit registers, AT1MAP1H, AT1MAP1M, and AT1MAP1L.
AT1MAP1H holds upper 2 bits of the 18-bit address, AT1MAP1M contains the middle 8 bits, and
AT1MAP1L contains lower 8 bits. Depending on the transfer mode, either all 18 bits are valid, or only the
least significant 8 bits (in AT1MAP1L) are valid. When only the 8 bits in AT1MAP1L are valid, the value
x'03F' is assigned to the 10 bits in AT1MAP1H and AT1MAP1M, and the pointer points to the I/O space
(special registers).
Memory pointer 1 also contains a computational function that enables it to increment the address based
on the transfer state.