First VAX-11/730 VMS Boot! (was: Re: VAX-11/730 %BOOT-F-Unexpected Machine Check)

[Mark J. Blair]

I have a DEC distribution panel and internal cable. The panel has a circuit breaker, a 15 pin D connector on the outer side for the transceiver, and another 15 pin D connector on the inner side for the internal cable between the DELUA card and the distribution panel. 

The back of the 730 chassis does not have an open slot for the Ethernet transceiver, as all of the other slots are already occupied. A bracket for the Ethernet bulkhead panel is screwed to one of the rack's rear panel brackets. Whoever routed the internal round cable before I got the machine did a less than perfect job, so it kept getting snagged when sliding the 730 chassis in and out. The cable jacket has many nicks, but they do not appear to penetrate the conductor jackets.

I've just tried reinstalling it, and things aren't moving smoothly yet. I don't think that round cable behaves properly in the flat cable flex area, so next I will see if I can find a clean path between the card cage and a different area of the chassis where I can route it along the gantry that supports the power inlet cable. The round cable just doesn't route as cleanly as the original bundle of flat cables, so I'll need to fiddle and cuss until I get it working well. 

Once I manage to route the internal cable, I'll plug in a DEC AUI cable to the bulkhead panel, and a DEC 10baseT transceiver, and see if I can get networking up.

The first time I started playing with VAXen as a student, there was generally a long AUI cable running to a vampire tap on thick yellow coax. Sometimes the coax was routed through the building, and occasionally there would be a vampire tap down in the stem tunnels with an AUI cable extending into a subbasement. I've never installed a vampire tap myself.

Then a couple years later at a different university, most of the easily accessible wiring was thin coax, and 10baseT was still newfangled. 



> On Jun 14, 2015, at 11:27, Johnny Billquist <bqt at update.uu.se> wrote:
> 
>> On 2015-06-14 19:25, Mark J. Blair wrote:
>> 
>>> On Jun 14, 2015, at 10:01, tony duell <ard at p850ug1.demon.co.uk> wrote:
>>> 
>>> If the connector on the DELUA board is a normal Berg-type header (and I think it is) then maybe you could
>>> use a piece of (twist-n-flat?) ribbon cable to make an extension that could be routed through the cable
>>> pan arrangement and then connected to the original DELUA cable back in the rack cabinet.
>> 
>> That might be a good approach. The DELUA end of the cable has a Berg connector, and the other end has the typical 15-pin D-sub AUI connector with a slide latch. I'll look up the cable wiring to see if signals that would best be twisted pairs are conveniently placed on adjacent odd/even pins, such that twisted pair ribbon cable would work well electrically.
>> 
>> Or maybe I can use the round cable that I already have, with P-shaped cable clamps screwed down using the screws at one end of the flat cable clamps. There may not be enough clearance in the tray for that.
> 
> What happened to the original cable and distribution panel?
> As a warning - the original distribution panel have a fuse for the 15-pin Dsub, to avoid excessive power use on the connector. If you go directly from the board to a transciever, you might run the risk of damaging the DELUA itself if something goes wrong.
> 
> Put another way. The design is to have an internal cable from the DELUA to a distribution panel at the back of the machine. There you have the 15 pin AUI connector, which have a fuse. You then had an external AUI cable from there to your transciever, which traditionally sat on a thick coax. Of course, later on, you started having thin ethernet. Still AUI cable and transciever, though. Eventually twisted pair showed up. But you had transcievers for that as well. And if you have room behind the machine, you could connect the thin ethernet or twisted pair transscievers directly to the distribution panel connector, so no actual external cable.
> 
>    Johnny
> 
> -- 
> Johnny Billquist                  || "I'm on a bus
>                                  ||  on a psychedelic trip
> email: bqt at softjar.se             ||  Reading murder books
> pdp is alive!                     ||  tryin' to stay hip" - B. Idol