HD64F2149 Datasheet, PDF (177/1035 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

Enabling or disabling of IOS signal output is controlled by the setting of the IOSE bit in SYSCR.
In expanded mode, this pin operates as the AS output pin after a reset, and therefore the IOSE bit
in SYSCR must be set to 1 in order to use this pin as the IOS signal output. See section 8, I/O
Ports, for details.
The range of addresses for which the IOS signal is output can be set with bits IOS1 and IOS0 in
BCR. The IOS signal address ranges are shown in table 6.4.
Table 6.4 IOS Signal Output Range Settings
IOS1
0
1
IOS0
0
1
0
1
IOS Signal Output Range
H'(FF)F000 to H'(FF)F03F
H'(FF)F000 to H'(FF)F0FF
H'(FF)F000 to H'(FF)F3FF
H'(FF)F000 to H'(FF)F7FF
(Initial value)
6.4 Basic Bus Interface
6.4.1 Overview
The basic bus interface enables direct connection of ROM, SRAM, and so on.
The bus specifications can be selected with the ABW bit, the AST bit, and the WMS1, WMS0,
WC1, and WC0 bits (see table 6.3).
6.4.2 Data Size and Data Alignment
Data sizes for the CPU and other internal bus masters are byte, word, and longword. The bus
controller has a data alignment function, and when accessing external space, controls whether the
upper data bus (D15 to D8) or lower data bus (D7 to D0) is used according to the bus
specifications for the area being accessed (8-bit access space or 16-bit access space) and the data
size.
8-Bit Access Space: Figure 6.3 illustrates data alignment control for the 8-bit access space. With
the 8-bit access space, the upper data bus (D15 to D8) is always used for accesses. The amount of
data that can be accessed at one time is one byte: a word access is performed as two byte accesses,
and a longword access, as four byte accesses.
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