18 Apr
2005
18 Apr
'05
8:20 a.m.
On Mon, 2005-04-18 at 00:59 -0700, Eric Smith wrote:
Heinz wrote about the PDP-11/55:
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.
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.
With QED95, even faster yet. But is it still an 11/70 at that point?
--
TTFN - Guy