HL-1650:

This printer has 8 Mbytes of standard memory and one slot for optional expansion memory. The memory can be expanded up to 136 Mbytes by installing commercially available dual in-line memory modules (DIMMs). (The standard memory installed varies depending on the country where it is purchased.)

HL-1670N:

This printer has 16 Mbytes of standard memory and one slot for optional expansion memory. The memory can be expanded up to 144 Mbytes by installing commercially available dual in-line memory modules (DIMMs). (The standard memory installed varies depending on the country where it is purchased.)

This printer uses memory modules that are: 100 pins, no-parity, SDRAM with 64Mbit or more. This printer is not compatible with Extended Data Output (EDO) DIMM, or DIMM that uses 16 Mbit SDRAM.