M16C User Manual.pdf

External BusesMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTER5.1 Overview of External BusesMemory and I/O external expansion can be attained in either the memory expansion mode or the microprocessormode. When accessing an external area in either mode, 8-bit data bus width or 16-bit data buswidth 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 anexternal area.Addresses (A0 through A19) for accessing a memory space of up to 1M bytes, as well as chip selects______________(CS0 through CS3) which indicate areas resulting from dividing a 1M bytes space into four, can be outputin both the memory expansion mode and microprocessor mode.Table 5.1.1. Memory space expansion mode and memory spacesExpansion modeNormal modeExpansion mode 1Expansion mode 2Accesible memory spaceUp to 1M byteUp to 1.2M byteUp to 4M byte508