Suggestions for VT103?

Josh Dersch derschjo at
Sat Dec 27 21:49:20 CST 2008

On Dec 27, 2008, at 7:19 PM, Steven M Jones <classiccmp at>  

> Josh Dersch wrote:
>> I understand it's possible to upgrade the backplane to 22 bits --  
>> how is this done?
> I have a VT103 (with cards), and a funky rackmount cage with three  
> separate Qbus backplanes in it (thanks Phil!) that may only be 18 bit.
> A while back I grabbed a number of bare Q22 backplanes off of eBay  
> in case I found I needed to replace the backplanes on these systems.  
> Haven't gotten around to even assessing feasibility, but the plan is  
> to try and just swap the backplanes whole. I've got a handful of  
> KDJ11-A dual-height CPUs to use if that works, though I'll probably  
> need some MXV11's or something to go with them.
> The bigger question, to my mind, is how to cheaply attach disks.  
> With the VT103 I believe some folks have placed small disks (3.5"?)  
> under the CRT, where the TU58 drives would have been on a  
> PDT-11/130. But you still need a drive interface to talk to 'em.  
> Perhaps one of the Micropolis half-height ESDI drives would fit, and  
> work with your controller.

I have a number of external TRS-80 external hard-disk enclosures,   
which at one point contained MFM-style drives -- since the cabling is  
the same as ESDI I was considering putting an ESDI drive in one and  
cabling it to the Emulex controller,  thus allowing an external drive  
and cutting down on space/power issues in the VT103.

> In addition I see two projects out there for Qbus disk interfaces:
> wintersweet:
> CHD's Q22-ATA:
> No further information, like availability or compatibility, and no  
> timeline for when I'll drag out the stuff I have and start  
> contributing ... ;^)

Man, One (or two!) of those things would be sweet!  I lucked out and  
snagged a CQD-220 SCSI controller off eBay for $80 last year,  but I  
doubt I'll ever find another SCSI controller for that price...

> --S.

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