Thanks for the info. You folks have been a big help. Now I'm stuck with the table. here is what I have so far.....

;**************
;this section is for initializing stuff – there will be more here later
;**************
; get timer ready so this doesn’t take time later

clr tr0 ;make sure timer 0 is stopped
clr tf0 ;clear the overflow flag
anl tmod, #0xF0 ;clear TR0 and TF0
orl tmod, #0x01 ;set to mode 1
mov tl0, #0
mov th0, #0 ;clear the timer value
mov r3, #0
mov r2, #0 ;clear the overflow count

;**************
;turn on int0
;**************

setb ex0 ;enable external 0 interrupt
setb ea ;global interrupt enable

;**************
;the code for interrupt 0
;this needs to be run from 0003h
;***************

setb tr0 ;start the timer
clr ex0 ;disable external 0 interrupt
setb ex1 ;enable external 1 interrupt
reti

;****************
;the code for interrupt 1
;this needs to be run from 0013h
;****************

clr tr0 ;stop the timer
clr ex1 ;disable external 1 interrupt
??????? ;here’s where I’m stuck
??????? ;I need to read the timer value, and store it in the FIFO table
setb ex0 ;enable external 0 interrupt
reti

*******************
You can see where I’m stuck. My guess is that in the initialization section, I need to create the table. I would greatly appreciate it if you could give me an example or 2 on implementing an FIFO table. All I need to do is push new data in (the timer0 value) and throw out the old data and calculate the average each time.

Thanks in advance for your help.

Chris Seeley