[comp.sys.apple] Memory expansion card problems

Franck@DACTH01.BITNET (07/25/88)

I've problems with my original Apple memory expansion card
(Serial# BCGS6Dsa26002). So I have an extra memory of 256KB, in
totality 512KB. All looks fine.

After installing additional memory chips of type
      TMS 4256-12ML
      EMI 728 OBMs
and setting jumper 1 (256KB more) or jumper 1 and 2 (768KB more) on
the card the system drops into the monitor and beeps after runnning
the inline memory test or writing to the Ram disk or loading any
application that uses mor than 512KB.

WHY THAT? Are the additional chips not compatible or faulty?
What of the chips is it ???

Please help. Thanks in advance.
                                   Walter August
                                  (FRANCK@DACTH01 via Bitnet)