I believe that the cnc is dated around 1980.I spoke with someone the other day,and they told me that these mm2102an-4 and 4l were the same animal and that they couldnt see anything different between them.Some one else said that they were resitors.??? I do not know what these chips are for or even if the call out 4-4l are the same. The reason that I suspected these chips,, I talked to a few electricians and they did look at the board and said that I should make sure that these chips were seated good in the sockets.After I removed a few of them and plugged them back in,I did get a new screen to show up on the crt. not 100% of the time so that is when I removed the board and broke a few pins trying for that better fix. I will buy new chips for the board. I do not know where this fix will go.Hopefully this will be a step in the right direction.I am willling to take the chance that these chips(3 pcs my fault) are bad and that this is a step towards fixing the board. Thank you.