Im trying to upgrade my old TP Link to be able to install latest OpenWrt I make correct image and now I'm looking for correct RAM chip, on device I have
zentel a3s56d40ftp-g5 and based on this post and this post they used this chip Hynix HY5DU121622DTP-D43 but according to this datasheat thats 32MB chip
and I need HY5DU12822D(L)T(P)-X and not HY5DU121622D(L)T(P)-X
so Im I wrong or what ?
The memory bus is 16 bits so you need a x16 chip. It has 32M locations that store two bytes each, so the capacity is 64 MB.
Hynix HY5DU121622DTP-D43 has 64MiB's ?
Yes its in the same family of chips with 512 Mbits. That is indicated by the 12 in the part number. The original chip has 56 in the part number, which is short for 256 M bits.
The difference is how many active I/O pins are used. The Atheros CPU requires 16 bits on each memory cycle, so with one RAM chip it must be a x16 chip. The x8 and x4 chips are used in modules where multiple chips make up a data word.
Aha ok @mk24 thanks for nice explanation