abstract.txt

这是单片机C51典型应用设计代码

von Neumann Memory Example
==========================
The following example program shows how you can build an application
for a target with CODE, XDATA, and von Neumann memory.

By default, the 8051 is a Harvard architecture.  CODE memory and DATA
memory are physically separate memory areas.  There is no way to write
to the CODE memory.  You can, of course, AND the /PSEN and /RD lines
of the 8051 and connect the output to the OE of a RAM.  The RAM will
be mapped into the CODE and DATA space of the 8051.  You can write
program code into the RAM and execute it.

This example uses the following memory map:

CODE:  0x0000-0xDFFF (ROM)
CODE:  0xE000-0xFFFF ('von Neumann' RAM)

XDATA: 0x0000-0xDFFF (RAM)
XDATA: 0xE000-0xFFFF ('von Neumann' RAM)

The program uses the XBYTE macro to write an LJMP 0xE000 instruction at
address 0xE000.  Then, the program calls the function at address 0xE000.
This function never returns, of course.

A debugger script creates mappings for the CODE and XDATA memory that
allows the Keil debugger to completely simulate this hardware configuration.

A breakpoint is set at C:0xE000 by the script.  To test this example, just
run the program or single-step through it.