well, some months ago i asked for help booting a pdp11/34 here at freaknet medialab :) well, i think now we have a more complete knowledge of the REAL problem ! the M7891 board (128K x 18 bit MOS MEMORY MODULE) have the D2 red led light turned ON when turning on the CPU ! this means PARITY ERROR on this board :( checking the board we found 2 problems: 1) a 74LS175 chip named E15 on our schematic diagram, that seem phisically BROKEN on an edge (there is a fessure on the plastic DIP package). i can't change it now because i don't have a soldering station here to do a nice job, but looking the chip i think it may work... 2) a 5 Kohm 4-resistor bridge named R22 on our diagram, that is phisically BROKEN. this bridge give +5V on signals named DATA OC L, CSR OC L, OC L and X ADD OC L. i changed it with a 4.7Kohm 4-resistor bridge, without any result. (maybe the 74ls175 is really broken :) an other ipothesys may be: some electrolitic capacitor in short circuit. we had this problem on a decwriter III ! :) the real problem is: if we aren't able to repair the M7891 board, where can we find a "new" one ??? can somebody help us ? it's a shame for us to have our pdp11/34 offline :(( any help is appreciated ! *:) -- [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 :::::: http://kyuzz.org/radiocybernet]