64MB RAM Mod
The Device uses a DDR1 16Mbit x 16bit (16Mibit*16=256 mebibit. 256 mebibit/8=32MiByte) 400MHz chip. Replace it with any 32Mbit x 16bit chip. 333MHz instead of 400MHz also works fine. It's quite hard to find these chips. The best chance is to have a look at DDR-SODIMM. Since there are no 64Mbit x 16Bit DDR1 Chips available → no 128 MB mod!
Working chips:
Hynix HY5DU121622DTP-D43 (From Mustang DDR-SODIMM 512 MB)
Hynix HY5DU121622CTP-J (PC333 DDR RAM)
Infineon HYB25D512160BE (From Infineon DDR-SODIMM 512 MB)
Additional list that may work:
Type ID Code Vendor
DDR 32Mx16 PC400 TSOP Pb Free HY5DU121622DTP-D43-C Hynix
DDR 32Mx16 PC400 TSOP Pb Free H5DU5162ETR-E3C Hynix
DDR 32Mx16 PC400 Pb Free K4H511638G-LCCC Samsung
DDR 32Mx16 PC400 Pb Free K4H511638J-LCCC Samsung
DDR 32Mx16 PC400 A3S12D40ETP-G5 Zentel
DDR 32Mx16 PC400 NT5DS32M16BS-5T Nanya
DDR 32Mx16 PC400 PB Free P3S12D40ETP-GUTT Mira
DDR 32Mx16 PC333 CL2.5 TSOP MT46V32M16TG-6T:F Micron
DDR 32Mx16 PC333 CL2.5 TSOP MT46V32M16P-6T:F Micron
DDR 32Mx16 PC333 PB Free TSOP EDD5116ADTA-6B-E Elpida
DDR 32Mx16 PC333 PB Free TSOP HYB25D512160CE-6 Qimonda
DDR 32Mx16 PC333 PB Free TSOP HYB25D512160CEL-6 Qimonda
DDR 32Mx16 PC333 PB Free TSOP HYB25D512160DE-6 Qimonda