好像只能用特定的指令访问
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HCS 12X has a complete set of Load & Store instructions to allow the 7 bit global address register to form a 23 bit global address:
GLDAA,GLDAB,GLDD,GLDX,GLDY,GLDS,GSTAA,GSTAB,GSTD,GSTX,
GSTY,GSTS
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If such an instruction is executed the address is concatenated from the new 7-Bit GPAGE register + standard 16Bit address
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23Bit address = {7-Bit GPAGE, 16 Bit address}作者: whc1223 时间: 2010-1-25 15:07
The upper byte of the 23-bit global address must be written to GPAGE in order to display the corresponding 64K region of the global memory map.
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Example: Writing 7E to GPAGE will result in the Global View Window displaying the contents of addresses 7E_0000 to 7E_FFFF.
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Remember that ONLY special instructions can access the Global View Window. These are called Global instructions and have the form.
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GLDxx and GSTxx作者: whc1223 时间: 2010-1-25 15:09
LDX #0x5000 ;Set GPAGE offset to the value of 0x5000
MOVB #0x14, GPAGE ;Initialize GPAGE register with the value of 0x14
GLDAA X ;Load Accu A from the global address 0x14_5000
