?5? MCS-51???

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?5? ??????????
5.1 ?????????? 5.2 ?????? 5.2 I/O????????

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5.1 ????????
????????? ?????????????????,???????
?ROM??8031 ????ROM,????????ROM??89c51?,????R
OM,??????????
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??????????

• ????P0-?8?
• P2-?8?
• ????P0
• ????RD?WR? ALE? PSEN
• (?? ????????? ?????????)

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5.2 ???????????????RAM???
?????????RAM??,???????????,???????????
RAM?????? ??RAM(DRAM),??????,????,??
???? ??RAM(SRAM),????????SRAM?
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1. SRAM???
??6264 ????62, ??SRAM ???6488k???? 62128
?128816k ???? 62256 ?256832k ????
6264 ???
6264 ???
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2. RAM??????
????????????? 1)??? D0n ?????? DB0n 2)???
A0N ????????AB0N? 3)??? CS ????????ABNx? 4)
???OE?WE(R/W) ???????RD?WR?
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(No Transcript)
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3. ????????
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???????
74LS373?74LS573?????????? 74LS273?11?G????????
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?????????, ?????????? ????
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4. 62128?MCS51???
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???????ROM???

• ???,ROM????????,????????(????),??????
• ??????
• 1. ??ROM????ROM
• ?????????????????????????????,??????
• 2. PROM???ROM
• ?????????????????????,??????,??????
• ????,??????,???????
• 3. EPROM????PROM
• ????????????????,???????PN????????,
• ????,???????????????????,????????,???
• ????
• 4. EEPROM????PROM
• ????????????,???????,????????,??RAM?
• ROM????????????

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1. ?????ROM???
27xx???
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2. 27128?MCS51???
?RAM???? ????ROM?,CE????
OE?PSEN
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3. MCS51????ROM?RAM
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?????????
1.??? ??????????????????????? 2.?????
?????????????????????????????????????????????
????
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1. ???
P2.7 P2.6 P2.5 P2.4 P2.3 P2.2 P2.1 P2.0
A7 A6 A5 A4 A3 A2 A1 A0 ? 1 1 0 0 0
0 0 0 0 0 0 0 0 0 0 0 C000H 1 1
0 1 1 1 1 1 1 1 1 1 1 1 1 1 DFFFH ?
1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0
A000H 1 0 1 1 1 1 1 1 1 1 1
1 1 1 1 1 BFFFH ?0110 0000 0000 00000111
1111 1111 1111 6000H7FFFH
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2.????? 3-8 ?????74LS138
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• Y0?Y1?Y2?????????????CE1?CE2?CE3

???????????
?0000H1FFFH ?2000H3FFFH ?4000H5FFFH
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3. ?????????

• ??????????,????????,?????????

?????74LS244?? ?????? ?????74LS245?? ??????
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5.2 I/O???????? ?. 8255?????I/O????
?. 8155???I/O???? ?. ?????I/O??
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?. 8255?????I/O????
1???I/O????

• ??TTL???COMS?????????????P0?
• ???,???74LS273?74LS373?74LS244????

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2?8255?????I/O?????????

• (1)8255?????????

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(2)????

• PA0PA7?PB0PB7?PC0PC7?24????3??????/?????,A??
  B??????,C???????A?B?C 3????????????

(3)????
8255?8???,?8????D0D7? ?????8051?P0??,
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(3).???

• ?????8255??RD??WR???RESET???CS??

(4).???

• A1 A0 ???
• 0 0 A?
• 0 1 B?
• 1 0 C?
• 1 1 ???

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3???????????

• (1)8255???? ??0???1,??2
• (2).????

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4?8255?????????

• (1)8255?????

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(2). 8255???
?8255?3?????????????????????????

• ??,???8255?A?B?C???????(????
• ?),????80H?
• ??(????)??
• MOV DPTR, 0003H 8255????? DPTR
• MOV A, 80H ????A
• MOVX _at_DPTR, A ??????????

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4?8255?????????

• (1)8255?????

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??8155???I/O??????

• 1?I/O???????????

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2?8155????? (1)8155??3??? ??RAM?I/O??????????
(2)???????
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(3)?????

• ?????/?????8??????,?8???6???????,??2????
  ???????

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3?8051????8155??????
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???????I/O??

• 1????????????????????,?????????????????????????RAM
  ??
• 2???????????

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3???????????