DecServer 550 chassis

Johnny Billquist bqt at
Mon Oct 19 12:03:02 CDT 2015

Not sure what you expect a "conversion" means. Creating new PROMs imply 
finding actual proms, a prom programmer, the code to program into the 
PROMs, and then just replace the proms on the card.
Only the last piece will actually require any modification of the card, 
and I would expect them to be socketed anyway, so replacing means just 
removing the old proms, and inserting the new ones.

The note also mentioned that you might want/need to install a pull-up. 
But it would still be an extremely simple process. You just need the 
right bits...


On 2015-10-19 18:28, jwsmobile wrote:
> I would appreciate thoughts on the conversion of the processor to normal
> PDP11 eproms.
> The page pointed to earlier has a mention of that too, but the poster
> had access to another "real" KDJ and I am guessing copied that.
> I don't have access to any version of the system with appropriate eproms
> and would appreciate any pointers to the binaries needed.
> As to the condition most of the material is the result of moving it from
> where it was stored.  It will be totally disassembled and tested before
> being brought back up.  There is about 5 or 6 large deep freeze (for
> reference) sized piles of material being sent for e-waste from the place
> that is pretty much just junk material under the weather.
> Think of this as a Dusenberg rescued from a barn though.
> thanks for all the suggestions and observations.
> Next thing to go over is a Sun 4/260 "mini" tower.  Gads those were
> heavy.  Back is still aching from moving that.
> Jim
> On 10/19/2015 7:32 AM, Ethan Dicks wrote:
>> On Mon, Oct 19, 2015 at 3:42 AM, Pontus Pihlgren <pontus at>
>> wrote:
>>> Interesting. I thought Tthe DECserver 550 was merely the big brother in
>>> the terminal server line. But it looks like it is essentially a
>>> PDP-11/53 with 1.5MW of ram, you need new boot roms though. Pretty nice.
>> Yep.  It's essentially an S-box KDJ11 with different ROMs.  I happen
>> to have a CPU board from one, but not the box itself.
>> One of these days, I plan to burn "real" PDP-11 ROMs and bring 2.11BSD
>> up on mine.  That and my Pro380 are my only KDJ11 machines.
>> -ethan

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