Apple Performa 6400/180 - Manual (Page 60)

Specifications Memory - 6
DRAM
6500/300
64 MB DRAM
Expandable to 128 MB using JEDEC-standard DIMM devices in two
sockets (168-pin, 5-volt buffered extended data out [EDO]
mode, 60 ns or faster, 2K refresh rate DIMMs)
ROM 4 MB of read-only memory (ROM)
PRAM 8K nonvolatile parameter memory
VRAM
6400
1 MB built-in video RAM
6500
2 MB built-in video RAM, 88 MHz synchronous graphic RAM