okay Patrick I get it .
That's what I did ,used a simuator wrote the code on a paper and again posted the stuff.

http://www.ikraft.biz/netbaba/p...serpat.txt

(The boundary decoration ain't uniform )
okay now back to your queries
SERIAL: JNB TI,$

what will it do if TI not set, first thing unless TI is set ,since REN is disabled, no interrupt would occur and hence no ISR will be executed.
If still TI is not set it keeps looping the same add till it is set.
If ti set it goes to clear TI , yes as I write this I can reduce a cycle by using JBC TI,$

CLR TI

cjne r0,#42h,next
if in the above instruction r0 = 42h then r0 is reset to 40 and data of 40h is transmitted to pc
If not then it jumps to increment r0 and mov content pointed by r0 into sbuf and hence to pc.


mov r0,#40h
sjmp out
next:inc r0
out:mov sbuf,@r0
RETI

Isn't the above code qualify to be called as an ISR for serial interrupt

the value has to be between 40 to 42 in r0
It can't suddenly jump to ff and so on..

I have modified the program to include all comments within the asm

Can you please ...Please make changes and send it back to me I am tired of going round the bush I need to complete my college project by 15th atleast give them a demo..

I have tried my level best . I am not doing the 'give me' thing but I have reached a limit of my understanding capacity...People have to tell me exactly what is wrong so I can further analyse and understand.

http://www.ikraft.biz/netbaba/p...serpat.txt

Thank you
Deepak