I found a WRT54GL when I was doing housework. At that time I was using a WHR54G, which is a cut-down version of WRT54 and is not a good platform for playing with OpenWRT. So I took a discarded FPGA board, desolder a chip of RAM from it. But it turns out that the pin layout of that chip is totally different from original one (TSOP48->TSOP56). So I took the whole afternoon checking datasheets from different RAM manufactory, tracing down the wire on PCB by microscope and multimeter. And finally came out with a chart showing the relationship between all 4 packaging that are designed on the PCB for mounting different RAM chips.

By using the chart I found that the “new” chip could be mount on one of the packaging with three pins wired out.

After that, the router was upgraded from 8M RAM to 64M.