Your Brother machine has 128 MB of standard memory and one slot for optional memory expansion. You can expand the memory up to 384 MB by installing dual in-line memory modules (SO-DIMMs).
In general, the machine uses industry-standard SO-DIMM with the following specifications:
Type: 144-pin and 16-bit output
CAS latency: 4
Clock frequency: 267 MHz (533 Mb/S/Pin) or more
Capacity: 256 Mbyte
Height: 30.0 mm (1.18 in.)
DRAM type: DDR2 SDRAM
There might be some SO-DIMMs that will not work with the printer.
For more information, call the dealer you bought the printer from or Brother Customer Service.