Difference between 2 PDP11 models

[Mike Cesari]

On Mar 10, 2005, at 3:49 PM, Guy Sotomayor wrote:

> On Tue, 2005-03-08 at 20:54 -0500, Bob Shannon wrote:
>> I used to own an 11t55.
>>
>> It has fast bipolar memory, and a dual unibus configuration.
>
> Yea, so does the 11/55 (actually the 11/45 and 11/50 also have a dual
> unibus config...since they're all based upon the 11/45).  So I ask
> again, what's the diff?
>
> Thanks.
>

I ran across this the other day while perusing a copy of the option
module list. [1]

These letter designations define different "pre-packaged" systems.
The "11T55" (actually all 11T's) are equipped with 1 or more rk05's.
For example, the description of an 11T55-BA is:
11/55-BA, FP11-C, RK11J-DE, RK05J-AA, 120V 60HZ.
The 11/55-BA has an LA36 and an 11/55-CA;
The 11/55-CA has
2 - MS11-CC (Controller for bipolar memory)
8 - MS11-AP (4k bipolar memory cards)
KB11-D, DL11-W, KT11-CD, and M9312.

An 11/55-CE is the above without the bipolar memory.

Mike

[1] This is a PDF file of the april 1983 option module list. It's on 
bitsavers
in the dec/modules directory. And it's almost 85MB long.