I am using P89LVRD2BN which has 768 XDATA RAM.I tried to extend my XDATA by providing external RAM through 74LS373 LATCH. so when I am definig more XDATA variables,I am expecting the variables shuld automatically assignd the addresses in External RAM. But these thing are not happening. My settings are EXTRAM = 0 and AO = 0.(Reset Values)
But in Real time interfacing with RAM,it is always sending 'f' to my hyperterm. whta is the problem? Almost certainly your hardware. Dig out your oscilloscope, and check that your chip enable is actually getting enabled, and that the address/data lines move as expected.