> If it were me, I'd start by setting up some tests to determine what exactly > the protocol analyzer is doing. If it really is dropping 0 bytes, then I'd
Well, I see 2 ways forward, in that I have found 2 things that look odd... One is to investigate the serial link between the VAX console processor and the TU58. The other is to see just why the data from the read amplifier looks odd and why the TU58 drive runs tapes off the spool (meaning it is not seeing the BOT marker). Intuitively I feel the latter is more likely to be the real problem. > probably hack up a home grown capture using a couple of serial ports. > If the controller and the VAX really are speaking the right protocol to > each other, then it's time to worry about the correctness of the data. On > the other hand, if the controller really is not sending all the bytes it > should, > I'd check for bit rot in the EPROM. The TU58 ROM checks against a dump I made of it years ago (OK, that dump might be bad). It also checks against a dump of ROM in my other TU58 (which has bad rollers I have not repaired yet). The power on self test of the TU58 does a checksum of the ROM (OK, not a very good test) and that passes. I think bit rot is unlikely given that. Furthermore from a read of the source code it appears the TU58 builds the response packet in RAM and sends it. I can think of faults that would cause it to be truncated. But not a fault that causes it to leave out bytes from the middle of it. -tony
