PDP11/55 sells on Ebay for 5K$ - was it really the fastest 11?

[Guy Sotomayor]

On Mon, 2005-04-18 at 00:59 -0700, Eric Smith wrote:
> Heinz wrote about the PDP-11/55:
> > claimed that it was the fastest PDP11 of
> > the blinkenlights
> > machines made by DEC.. Is that true?
> 
> With bipolar memory, the 11/45 or 11/55 are definitely the fastest
> DEC machines with "real" front panels.
> 
> >  I expected  an 11/70 to be instruction for instruction faster
> 
> No.  The cache was roughly the same speed as the bipolar memory of
> the 11/45 or 11/55, but main memory was slower.  And access to Unibus
> was slower.
> 
> > How about compared to a 11/70 with a PEP70 instead of factory memory and
> > cache?
> 
> With PEP70 (replaces DEC main memory) it should be faster.  With PEP70 and
> HC4x Hypercache (replaces DEC cache) it should be much faster.

Just from running a simple blinking lights test, I can tell you that the
11/55 *is* faster than an 11/70 with PEP70 & Hypercache.  I've run the
program on both and the 11/70 blinks the lights *fast*.  When I run it
on the 11/55 you can't see the lights!  At first I thought the 11/55 had
serious problems.  Once I put in a longer delay than I usually use it
was still faster but you could actually see the lights.

> 
> With QED95, even faster yet.  But is it still an 11/70 at that point?

-- 

TTFN - Guy