Very-very strange but found solution for gflorez's "disk operation crashing" problem!
I tried many different CPUs, it is change the effect, for example with NEC or ST CPU frozzen before the "ENTERPRISE" screen...
With new CMOS CPU are little more stable but not perfect...
And found the problem also exist with one unmodified MICROTEAM card (no SRAM and FLASH ROM), DIR A: crashing...
Finaly I putted back the original EXOS ROM, and disk worked!
then burned EXOS 2.4 to EPROM, and also worked!
Then the problem will be the FLASH chip? Tried with AM29F040, and working!
So, something very strange incompatibility with Winbond and SST chips
Now I'm ordering 128K AMD or MX chips and will check it.