DecServer 550 chassis

Johnny Billquist bqt at
Mon Oct 19 11:17:27 CDT 2015

On 2015-10-19 16:32, Paul Koning wrote:
>> On Oct 19, 2015, at 3:42 AM, Pontus Pihlgren <pontus at Update.UU.SE> 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.
> It's been a while, but I think it may be a member of the "pluto" family.  The original plan for terminal servers was that they would run CTERM.  But the initial Pluto terminal server was incredibly slow, not surprising given how complex that protocol is.  So an AD project was started which created LAT, originally also in a PDP-11 processor (perhaps even the same one, I forgot).  And that turned out to be so superior in practice that it ended up being the main product instead of the original plan.  But we still have CTERM as a leftover from all this.

Yeah, that should be PLUTO.
It's based on RSX, and talks LAT. I never knew that they considered 
using CTERM (a horrible protocol).
The interface in PLUTO, once it has booted, is pretty much like other 
DECservers, as far as I understand. But they were larger, more flexible, 
and so on, than later DECserver models, since they were built on PDP-11s 
in a Qbus chassis.


More information about the cctalk mailing list