HP Laserjet ..again....

As I stated earlier, I have cannibalized three HP laserjet series II printers. In looking over the parts recovered I find that I have three (3) totally different memory boards. The first is populated with small chips on BOTH sides of the board with a total of 128 soldered in chips that appear from their part numbers to be 256K memory chips, That is the number 256 appears within the part number. Now I don't know how wide the buss is but I am assuming 8 bits because of its age. If so this board is a 4 Megabyte memory board. The second is only half populated with 16 soldered in chips on one side that have the number 1000 in their part number so I am assuming they are 1meg chips and using the afore mentioned logic I come up with a 2Megabyte memory board. The third is fully populated with 32 socketed chips with the number 1000 in their part number and that works out to a 4 Megabyte memory board. Is my logic sound? Do I have two 4 meg boards and a 2 meg board? What is the largest memory board the Series 2 could hold? I am assuming that the socketed memory is best because it is easily repaired, but are there any problems with the socketed memory having bad contacts after time?