Hi, In my PC-1500 i had problems with the first TE-1507 version using Xicor memory.
It was impossible to write something in an unprotected X28HC256.
http://www.pc-1500.info/2015/07/30/te-1507-the-memory-module-for-developers/

The Team1560 needs were to have a big system RAM and a place to test system ROM extensions.
Done ! The TE-1507 is now working with 2 RAM ICs and the R/W protection is done by jumper.

Here are some pictures the prototype :

This one, number 3, is reserved for…….. ? Stay tuned 😉

The release version should be available in one month.