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Chapter 14 Automatic Transfer Controller
Operation
XIV - 26
14-3-14 Transfer Mode 9
In transfer mode 9, ATC1 automatically transfers one byte of data two times every time an ATC1 activation
request occurs.
(1)
(2)
(3)
(2)
AT1MAP0
AT1MAP0 + 1
AT1MAP0 + 2
AT1MAP0 + 3
AT1MAP1 (odd)
Memory Pointer 0
00000 - 3FFFF 03F00 - 03FFF
Memory Pointer 1
(Only lower
8 bits are valid)
AT1MAP1 (even)
In this mode the transfer direction indicated by memory pointers 0 and 1 reverses for the second data
byte transfer.
In the first data byte transfer, the I/O space address (x'03F00' - x'03FFF') in memory pointer 1 is the
source address, and the address in memory pointer 0, for any memory space, is the destination address.
When the first data byte transfer ends, the address in memory pointer 0 increments by one.
In the second data byte transfer, the incremented address in memory pointer 0 becomes the source
address, and the I/O space address (x'03F00' - x'03FFF') in memory pointer 1 becomes the destination
address. The address in memory pointer 0 remains unchanged after the second data byte transfer ends.
Set an even I/O address in lower 8 bits of memory pointer 1 (AT1MAP1L). The upper 10 bits of the I/O
space address (x'03F') need not to be set in AT1MAP1H, AT1MAP1M.
Figure 14-3-11 Transfer Mode 9
Always set an even I/O address in memory pointer 1. In this double transfer of a data byte
from and to the I/O space, ATC1 targets the even I/O address set in memory pointer 1 and
the odd address that immediately follows it. In this mode, the first data byte transfer ac-
cesses an even I/O address and the second data byte transfer accesses an odd I/O ad-
dress.