ha ha…
kind of completed,
instead of 89C51 i’m planning to use 89C51RD2, (i heard RE2 having inbuilt EPROM)
saw 100000000 of errors BTW.
but still unable to interface EPROM, other than that all is working properly.
if i interfaced EPROM it will shoe “ADDRESS OVERFLOW ERROR”
for that we have to use XDATA, that is not working 
, i need EPROM to store last trip value.
any ideas????
finally
wysiwyg_imageupload:8595: last line il LOL ,
speed || trip||
distence aproximation || fuel remaining|| engine temperature || light sense
battery level|| fuel tap sense ( Mains,Reserve,Empty)|| mailge -( distence/(init fuel – fuel at that distence))