Apple Performa 6400/180 - Manual (Page 58)

Specifications Memory - 4
Memory
DRAM
Performa 6400, 6410,
6420
16 MB DRAM (6420 ships with up to 24 MB DRAM)
Expandable to 136 MB using JEDEC-standard DIMM devices in two
sockets (168-pin fast-paged mode, 70 ns or faster,
2K refresh rate DIMMs)
Power Macintosh
6400
16 MB DRAM
Expandable to 136 MB using JEDEC-standard DIMM devices in two
sockets (168-pin, extended data out [EDO] mode, 60 ns or
faster, 1K or 2K refresh rate DIMMs)