Memory –Random Access Memory Read/Write, volatile –Read-Only Memory Program, non-volatile Programable ROM Erasable PROM –UV EPROM –Electrical EPROM –Flash memory –Serial EEPROM

8051 write to 6264 –A0~A12  / 解碼電路  CS –D0~D7  –WR  8051 read from 6264 –A0~A12  / 解碼電路  CS –RD  –  D0~D7

READ –1. CS  –2. A0-A12  –3. RD  –4.  D0-D7 WRITE –1. CS  –2. A0-A12  –3. D0-D7  –4. WR 

READ –1. CS  –2. A0-A12  –3. RD  –4.  D0-D7 Program

101x xxxx xxxx xxxx = A000h = BFFFh 001x xxxx xxxx xxxx = 2000h = 3FFFh

–DPL  P0, DPH  P2 –ALE  –A  P0 –WR  MOVX –DPL  P0, DPH  P2 –ALE  –RD  –A  P0

000x xxxx xxxx xxxx = 0000h = 1FFFh 101x xxxx xxxx xxxx = A000h = BFFFh

Fetch instruction –PC L  P0, PC H  P2 –ALE  –PSEN  –Instruction Register  P0 MOVC –(DPTR+A) L  P0, (DPTR+A) H  P2 –ALE  –PSEN  –A  P0

__data unsigned char test_data; __xdata unsigned char test_data; __xdata __at 0x7ffe unsigned int chksum; __idata unsigned char test_data; __code unsigned char test_code=‘A’; bit test_bit;

__code __at 0xA000 unsigned char x=‘1’; __xdata __at 0x2000 unsigned char y; y=x;

__xdata __at 0x3000 unsigned char x[1024]; for(i=0;i<1024;i++) x[i]=i;

Stack

110x xxxx xxxx xxxx = C000h = DFFFh __xdata __at 0xC000 unsigned char x[8192]; int i; for(i=0;i<8192;<i++) –x[i]=0;