Hi, Do you remember the broken chip on pdp11/34 ? well, i changed the HC74LS175P with an original SN74LS175N. Now i can write and read correct data on memory :))) and the RED LED "PARITY ERR" on the M7891 board turn OFF while pdp11 is running a program. :))) BUT the pdp11 can't boot: the boot loader program stop after few steps. some details will follow in the next days; now i can't make any further test ... -- [asbesto : freaknet medialab : radio#cybernet : GPG key on keyservers] [ MAIL ATTACH, SPAM, HTML, WORD, and msgs larger than 95K > /dev/null ] [http://www.freaknet.org/asbesto IW9HGS http://kyuzz.org/radiocybernet]