On 26 Mar 2010 at 14:43, John Robertson wrote:
An old trick for testing DRAM in circuit is to simply
press over the
suspect RAM a known-to-be-good RAM with the pins tightly touching. In
many cases DRAM failures relate to failing pull-downs and thus a good
DRAM in parallel will take the load and provide good results.
Again, I apologize for stating the obvious.
But it would seem to me that if there were a problem with the SRAM on
the MDA, one could easily deduce this with a simple memory test, as
the MDA DRAM is memory-mapped in the PC's address space.
If it tests good, then in all likelihood, the fault is somewhere
else.
--Chuck