Serial UNIBUS Repeater?

tony duell ard at
Mon Jun 15 13:41:20 CDT 2015

> That's a much better description of the 730's mechanical peculiarities than I came up with. I was more concerned 
> with cable management between the two racks, since I have them in a tiny room where I need to roll them 
> around to get access to the back (it's literally a tiny bedroom in a manufactured home... basically a doublewide 
> trailer that's been fastened to a foundation after having the axles and drawbar cut off!). It's already tricky to roll 
> the racks back into place without running over the power cables, tape drive cables, serial lines and power 
> controller cable. But managing the cables in the cable tray area is another thing that needs to be done right.

My 11/730 was totally decabled to get it to me. I think I have most of the original cables, and most of the 
metalwork. I've read the descriptions in the hardware manual on bitsavers and I am not looking forward to 
routing all those cables... Oh well....

It's a nice idea for a system that is not going to change, but adding or removing cables for a particular
peripheral option is going to be painful. I suspect routing all the cables between the trays on a bench and 
then mounting the bits in the rack is OK. But since the rack part of the tray has to be fitted before the CPU 
box sildes, removing it every time you want to add or remove a cable is not practical and fiddling a cable in
or out is going to be non-trivial. So not really a good idea for the likes of me who is always changing things.

That's why I am thinking of adding a BA11K or something on top.

> Based on the hardware user's guide that I have (and which I do plan to scan and share), I gather that UNIBUS 
> expansion cabinets would generally be used in a configuration that's in a larger rack and has both TU58 slots 
> on the front panel. I haven't seen one of those in person before. My system is the configuration that's in one or 
> two short racks. The main one is completely filled by the RL02, VAX-11/730 and R80 drives, from top to bottom. 
> The other rack contains the optional TU80, with an unused bay below it. I haven't measured the size of that 
> unused bay yet, but it looks like it may be tall enough for a UNIBUS chassis. Maybe I could adapt one of my 
> empty PDP-11/44 chassis boxes for use as an expansion chassis?

Are you sure this manual isn't aready on bitsavers. I have an installation manual and a user manual from
there that covers this stuff.

As I understand it. my 11/730 system was originally 2 racks. One was the normal CPU + R80 + TS05 tape
The other was a Unibus expansion box. I did get the cabling and boards to set this up, but not the 
second rack cabinet. Not that I really wanted it. My CPU box is the 'normal' one with built-in TU58s.
one on the front, one on the side.

> Or another possible use for that slot could be for my Kennedy 9610 tape drive. The TU80 looks like it probably 
> has a Pertec interface, so I should be able to add the Kennedy drive to the chain to get more BPI options in the 

The TS05 I have is certainly a (formatted) Pertec interface.


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