Recently, i decided to update the EOS 4.01 in one of my EMU's to 4.6.1. I used a 'Flashprep' disk first then rebooted with the 4.6.1 disk for the installation. The EMU loaded most of the OS then threw up a 'csum failure' error. After this, the machine would not boot to ANY OS.
To significantly truncate the story, this 'csum failure' was a result of a bad dram dim also known as CPU Ram. I discovered this by doing a RAM test. The machine repeatedly threw up a 'General Trap Error'. I then decided to take a DRAM module from one of my other EMU's. I ran the RAM test again and it passed without error. (luckily i have 2 other EMU's) I put the suspect DRAM in the other EMU an ran the RAM test, again the General Trap Error appeared after about 1 minute. I proceeded to update the EOS again this time with the known good DRAM from the second EMU. The procedure went smoothly and successfully.
Where to locate this DRAM ?
When the front of machine is facing u, if u look to the front right inside the machine u see 2 slots, the one closest to the front of the machine is a 'Flash' module and is printed on the the logic board, the one behind is the 'DRAM' dim. Luckily i had a few spare 72pin dims (which are just standard 8 meg 72pin simms u can use 4 meg , 16 works as well thats what i installed) around to replace the dodge one.
All is wikid now an runin smoothly so far.
Just thought i'd post this info for others who may experience the same 'csum failure' while updating the EOS. Once archived this should be real easy to locate with the search engine.
Laiterz