I had a problem with a mpu 327-4 the board got shorted to one of the mounts, destroying the 74154, but that was not all, for some reason the crystal stopped oscillation. I replaced the crystal with the same type, now it will not boot correctly. It will boot into the leon test mode and i tested all the 6821 outputs and all worked fine, with the exception of pins 2-9 connected to the switch returns, but i assumed the 74240 was holding them low as they are configured as inputs. All data and address lines are functioning as well as the irq. I thought that it might be the displays i replaced the display board(i had another good working board) and to joy. So .. i am not sure where to go from here. My suspicion is that the ram might be damaged or the eprom. I have a device to check all the 7821's and they all are fine changed the cpu. does anyone have an image of the mpu327 rom i can use to burn a new rom or test against mine?