DecServer 550 chassis

jwsmobile jws at
Mon Oct 19 16:11:58 CDT 2015

On 10/19/2015 12:39 PM, Johnny Billquist wrote:
> Well, you did ask for "thoughts in the conversion", so I gave you 
> mine. Sorry if you felt they were unhelpful. I just thought the 
> "conversion" was basically a no-work. Programming proms is something I 
> have spent more time than I can count on, and is so routine that I 
> don't even think about it.
I didn't mean that in disrespect.  The contents of what I posted was on 
the page and I basically needed the binaries and needed some direction 
as to which went where.  I appreciate you taking time to reply, but am 
coming from a lot less capability than you have.  I do a lot of 
computing and the like, but I've purposely not kept up with eprom 
technology to the point that i can't reliably swear I can program them 
right now.

There are only so many things one can keep up with and eproms were not 
one that was cheap to follow, and I was more into EE type devices anyway.

I may need a favor by swapping you some of my eproms (I have a 12" x 12" 
x 12" box of pulls) maybe to get you to make me a set for my board.

I've pulled out probably 500 and returned them to the original owner and 
owe him more.  but I do probably have a lot of the 27xx proms.

Do you think these are 27C or just straight 27 type eproms, and if so 
what speeds?  That is what I need to know too.

>     Johnny
> On 2015-10-19 20:57, jwsmobile wrote:
>> On 10/19/2015 10:03 AM, Johnny Billquist wrote:
>>> 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.
>> That is basically what I said.  I don't have one that isn't part of a
>> DecServer and i need images, or someone with a non DecServer to provide
>> them.
>> I guess you restated what I said.  if you have one, I'd appreciate 
>> copies.
>> I didn't post the original link from the top of this thread, you might
>> want to read it.  I'm just stating what someone did back in the 2001
>> time frame and posted a page about the conversion and info on his
>> experiences.
>>> 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...
>> What I said.
>>>     Johnny
>>> 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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