Mr.Philip

Messages from ROM are properly getting displayed.

The RAM used by me is bq4013yma-70.I suppose this 70 means 70ns,but is this has any effect in accessing using 8015 @ 12MHz? Am I doing right by using this chip @12 MHz? This is my basic doubt.And also upto what value I can go(like 100,120,80,85 etc)

As far as ISRs are concerned,I am disabling the ex0 & ex1.

One more peculior behavior with RAMS.
I have 2 RAM modueles of Dallas Semiconductor.
1.DS1254Y-100 on which PHILIPPINES is written
2.DS1245Y-100 ,no PHILIPPINES written
and ofcourse the Benchmarq chip.With th chip pf Sr.no.1 , I am able to display my message onto LCD properly,where as the No.2 and Benchmarq RAMs are not giving messages,what must be the root cause.

Please help me.I will highly thankful to you
Srikanth