单片机第七章MCS-51单片机扩展存储器的设计

1、图图 7 - 1P2.0P2.1P2.2P2.3P0.0P0.1P0.2P0.3P0.4P0.5P0.7P0.61817141387431916151219652234567821192223171615141311109202930242322213233343536373839111D7D6D5D4D3D2D1D0Q7Q6Q5Q4Q3Q2Q1Q0A11A10A9A8A7A6A5A4A3A2A1A0O7O6O5O4O3O2O1O0OE/VPPALEPSENG OEGNDGND2412 18VCC GND CEEA31GND803127324K874LS373 5 V图图 7 - 2A71A6

2、2A53A44A35A26A17A08O09O110O211GND12O313O414O515O616O717CE18A1019OE/VPP20A1121A922A823VCC242732图图 7 - 37 - 3其中，A0A11为地址线；O0O7为数据线； CE为片选线；OE/VPP为输出允许/编程高压。 除了12条地址线和8条数据线之外，CE为片选线，低电平有效。也就是说，只有当CE为低电平时，2732才被选中，否则，2732不工作。OE/VPP为双功能管脚，当2732用作程序存储器时，其功能是允许读数据出来；当对EPROM编程（也称为固化程序）时，该管脚用于高电压输入，不同生产厂家的芯片

3、编程电压也有所不同。当我们把它作为程序存储器使用时，不必关心其编程电压。A71A62A53A44A35A26A17A08I/O09I/O110I/O211GND12I/O313I/O414I/O515I/O616I/O717CE18A1019OE20WE21A922A823VCC246116图图 7 - 47 - 4P2.0P2.1P2.2P2.7P0.0P0.1P0.2P0.3P0.4P0.5P0.7P0.6181714138743191615121965223456781819222317161514131110930282322213233343536373839111D7D6D5D4D

4、3D2D1D0Q7Q6Q5Q4Q3Q2Q1Q0CEA10A9A8A7A6A5A4A3A2A1A0I/O7I/O6I/O5I/O4I/O3I/O2I/O1I/O0ALEG OEGND2412VCC GNDGND803161162K874LS373WEWR1627 5 VRD1722 OE图图 7 - 57 - 5D7Q7Q0D074HC373A12A11A10A9A8CEA7A0D7 D0 OEP2.7P2.6P2.5P2.4P2.3P2.2P2.1P2.0ALEP0PSENWRRD80C51IC02764IC02764D0 OECEA12A11A10A9A8A7A0D7IC02764D0 OE

5、CEA12A11A10A9A8A7A0D7 D0 OECEA12A11A10A9A8A7A0D7A8A9A10A11A12A8A9A10A11A12A8A9A10A11A12A12A11A10A9A8IC12764D0D0D0D0D7D7D7D7OEOEOEOEA0A0A0A0A7A7A7A7A0A0A0A0A7A7A7A7A8A8A8A8A9A9A9A9A10A10A10A10OEOEOEOECECECECEA11A11A11A11A12A12A12A12A10A10A10A10A0A0A0A0OEOEOEOEA7A7A7A7A8A8A8A8A9A9A9A9A12A12A12A12A11A11