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M30245 Group
4.1 Overview of External Buses
Memory and I/O external expansion can be connected to microcomputer easily by using external buses.
When memory expansion mode or microprocessor mode is selected for processor mode, some of the pins
function as the address bus, the data bus, and as control signals and this makes the external buses be able
to operate.
When accessing an external area, 8-bit data bus width or 16-bit data bus width can be selected, based on
the BYTE pin level. 16-bit width is used to access an internal area,regardless of the level of the BYTE pin.
Fix the BYTE pin either to "H" or "L" level. 8-bit and 16-bit data bus widths cannot be used together in an
external area.
www.DataSheet4U.com
Make sure the BYTE pin is fixed to "H" level when an 8-bit bus width is selected and "L" level when a 16-bit
bus width is selected.
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
page 330 of 354
4. External Buses
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