Chapter 8 1. Which of control signal lines can be used in the off-chip memory ex
ID: 2293499 • Letter: C
Question
Chapter 8 1. Which of control signal lines can be used in the off-chip memory expansion of MCS-51 single chip microcomputer ? Please explain the functions of each control signal line. 10. In single chip microcomputer, we use one chip EPROM2764 and one SRAM6264 to expand memory storage. Assume the initial address of ROM is 000H, and the initial address of RAM is 2000H. Please draw the system circuit scheme, then show the address range clearly. Chapter 8 1. Which of control signal lines can be used in the off-chip memory expansion of MCS-51 single chip microcomputer ? Please explain the functions of each control signal line. 10. In single chip microcomputer, we use one chip EPROM2764 and one SRAM6264 to expand memory storage. Assume the initial address of ROM is 000H, and the initial address of RAM is 2000H. Please draw the system circuit scheme, then show the address range clearly. Chapter 8 1. Which of control signal lines can be used in the off-chip memory expansion of MCS-51 single chip microcomputer ? Please explain the functions of each control signal line. 10. In single chip microcomputer, we use one chip EPROM2764 and one SRAM6264 to expand memory storage. Assume the initial address of ROM is 000H, and the initial address of RAM is 2000H. Please draw the system circuit scheme, then show the address range clearly.Explanation / Answer
The three control line signals in MCS-51 that are used for external memory access are-
EA(External Access) :- It is an active low input signal to 8051 microcontroller. when logic zero is applied to this pin, then 8051 microcontroller access from external program memory only. When logic 1 is applied then it access internal and external program memories.
PSEN(Program Store Enable) :- It is active low output signal. It is used to enable external program memory. When the signal is logic low, then external program memory is enabled and microcontroller starts reading from external memory location. This signal is connected to output enable pin of external program memory(ROM). It is activated twice every external ROM memory cycle.
ALE(Address latch enable):- It is active high output signal from MCU. When it goes high, external address latch gets enabled and lower address of external memory (RAM or ROM) latched into it. Thus it separates A0-A7 address from AD0-AD7. The ALE pin is used for demultiplexing the address and data.