I'm relatively new to Atari repair, currently trying to order replacement I.C.'s for my Rev. 16 Atari 2600, but am having some trouble figuring out which labels mean what on each chip. Attached is an image of the chips on my 2600. From what I gather, the C0... label is the part number, but what do the other two(or one in the case of the middle chip) labels signify? And more importantly, do they have any relationship with the type of chip it is?