Dilog DQ614 - Third Chapter

Hello. About the probes with the DILOG DQ614 over one PDP-11/23 PLUS with one MFM hard disk using the diagnostics program for these board, I have some matters to speak about: * Somebody spoke about a possible modification of the U55 chip. I have the reference of the chip mounted. It's the 55U-91358. In fact, the order number of some chips of the board is: 25U-91353 69U-91354A 64U-91355 21U-91356 22U-91357 55U-91358 The question is: Could be used some XXDP diagnostic to determine the possible problem of the board that I told in my previous message about it ? * I want to use another hard disk, one IBM MFM full height of 44 Mb. Is one Type 31 (for the IBM PC) disk. Somebody has the complete geometry of it ? I don't have it actually available in the BIOS of my PCs, but I suppose that one 486 or 386 could have it. Thanks and Greetings Sergio