Depends on the size of your Zip Chips.
If you fill them all with 1M×4 Zip Chips, you will have 16Mb (16 Sockets)
Fill them all with 256k×4 80 ns DIPs, you will have 4mb, but these must be done in groups of eight, thats one entire bank.
However, all the banks have to have the same sized/type of chips. The RAM chips can be either static column or page mode ones. Static column Zips are 10% faster & support burst memory access.
The 8 Sockets under the Fast Ram sockets are to add another 1Mb of Chip Ram via 44256k 120 ns DRAM DIPs, just in case you only have 1Mb Chip Ram in your rig, & that 1Mb is Soldered to the Mobo.
Cheers! :-)