M16C User Manual.pdf

Memory Space Expansion FunctionsMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTERMemory Space Expansion FeaturesHere follows the description of the memory space expansion function.With the processor running in memory expansion mode or in microprocessor mode, the memory spaceexpansion features provide the means of expanding the accessible space. The memory space expansionfeatures run in one of the three modes given below.(1) Normal mode (no expansion)(2) Memory space expansion mode 1 (to be referred as expansion mode 1)(3) Memory space expansion mode 2 (to be referred as expansion mode 2)Use bits 5 and 4 (PM15, PM14) of processor mode register 1 to select a desired mode. The externalmemory area the chip select signal indicates is different in each mode so that the accessible memory spacevaries. Table 1.8.1 shows how to set individual modes and corresponding accessible memory spaces. Forexternal memory area the chip select signal indicates, see Table 1.12.1 on page 34.Table 1.8.1. The way of setting memory space expansion modes and corresponding memory spacesExpansion mode How to set PM15 and PM14 Accessible memory spaceNormal mode (no expansion) 0, 0 Up to 1M byteExpansion mode 1 1, 0 Up to 1.2M bytesExpansion mode 2 1, 1 Up to 4M bytesHere follows the description of individual modes.(1) Normal mode (a mode with memory not expanded)‘Normal mode’ means a mode in which memory is not expanded.Figure 1.8.1 shows the memory maps and the chip select areas in normal mode.Normal mode (memory area = 1M bytes for PM15 = 0, PM14 = 0)Memory expansion modeMicroprocessor mode00000160040016XXXXX16Internal area reservedExternal areaInternal area reserved0400016080001628000163000016D000016YYYYY16FFFFF16SFR areaInternal RAM areaInternal ROM areaType No. Address XXXXX16 Address YYYYY16M30622M4 00FFF16 F800016M30620M8 02BFF16 F000016M30620MAM30620MC/ECM30622M8/E8M30622MAM30622MCM30624MG/FG02BFF1602BFF16013FF16017FF16017FF16053FF16SFR areaInternal RAMareaInternal area reservedExternal areaE800016E000016F000016E800016E000016C000016CS3 (16K bytes)CS2 (128K bytes)CS1 (32K bytes)Note 1: These memory maps show an instance in which PM13 is set to 0; but in the case of M30624MG/FG, they show aninstance in which PM13 is set to 1.Note 2: The memory maps in single-chip mode are omitted.Figure 1.8.1. The memory maps and the chip select areas in normal modeCS0Memory expansion mode: 640K bytesMicroprocessor mode: 832K bytes22