TU58 problems

tony duell ard at p850ug1.demon.co.uk
Sat Jan 16 14:15:51 CST 2016

> > Does anyone have any sensible ideas as to what to try next. At the moment I have no idea if
> > it's the tape, heads, roller or what....
> >
> This might not be what you want, but I boot my 11/730 from a tu58
> emulator running on a linux box.  I used a little ttl<->rs232 converter
> board.  It works well and is reliable.

I had considered that, or one of the TU58 emulators that use SD cards or 
similar but (a) I am trying to restore this VAX, not make a machine that runs
VAX software and is not original and (b) I do have this moral objection to 
using more components to load the microcode than in the rest of the machine.

AFAIK the TU58 interface (at least on the 11/730) can run at RS232 levels, you
don't need a level shifter board.

> If nothing more, it will let you load the microcode so you can check out
> the cpu.

True, but it is one more thing I have to set up and debug. 

> That R80, however. mmm.  Those are cranky.  And noisy.  At first I put a

Mine might be worse than most....

I took it apart 20 years ago (no not the HDA) to (a) get it out of the rack -- it's
heavy and (b) to repair some damage to the casing. Never did the latter,  I didn't
really have the tools at the time. And you guessed it, I can't find all the bits now.

Fortunately I have the main bits -- the casing, the HDA, the PSU, the spindle motor,
the 4 main PCBs, etc. What I am missing are all the nuts and bolts (and being UNC 
they are not easy to get over here), some of the internal cables (trivial to make IDC
ribbon cables), the motor belt (ouch!, it's different on 50Hz models) and the hardest
to make, the brackets for the gas struts. I have the gas struts but not the brackets, 
clevis pins, etc to fix them to the bottom case and logic chassis. Making those will
be 'fun'. They may still turn up of course...

> UDA50 in to boot off more modern disks.  But that took 2 slots so I

I do not want a Unibus expansion cabinet, I want to put everything in the CPU box. 
Which means I really want to keep that R80 on the Integrated Disk Controller (I do
not want to try running from RL02s!). This, alas, means I am not going to have 
ethernet since AFAIK you can't run the cable through that odd cable tray thing on
the 11/730. And a UDA50 is out!

In any case, what would I link a UDA50 to? RA8x's are going to be as bad as the R80
(very similar design). RA90s, well, I met those in 'real use' in the 1990's. No thanks!


> ps: tu58 controller boards are easy to find.  I have at least 4-5 of
> them.  The rollers are the issue, when they turn to goo.

The controller is also not hard to fix. I have the printset, there is nothing I don't
understand about it. 

Yes, my rollers have turned to goo. I've tried suitably-sized O-rings on home-made
metal hubs. The tape seems to move at the right speed, given the data rate is right
some of the time (and when it isn't, I don't think it's the roller slipping)


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