18 Oct
1998
18 Oct
'98
12:19 a.m.
>To further complicate matters, within digital the
CPU is identified
>differently based on whether it has PMI memory installed or not.
>(And, of course, it matters whether the PMI comes before or after
>the CPU in the backplane!) So, for example, you may find a 18 MHz
>CPU with non-PMI memory called a 11/73, but with PMI memory it's called
>a 11/83.
In fact... you could find the system with PMI memory,
but installed
in the wrong place, and it will be identifed - by software - as an
11/73B. If you put the same memory in the right place, it will be
identified as an 11/83.
And if you put the FPP in your pocket instead of the CPU board, it
won't be identified by the software either :-). Your point is good
though - you've got to put PMI memory in the right slot or you don't
get the advantages!
>If, indeed, you have the 11/84 capable version,
you'll also need the
>KDJ11-B and the 11/84 backplane, along with PMI memory, to have a
>real 11/84 CPU.
But the board with Qbus memory in the qbus of an 11/84
system box
should work...
There are lots of never-officially-supported combinations which
do work.
I've also taken one of the KDJ11-B 18mhz boards,
removed the 18mhz
clock and replaced it with a 20mhz clock... the boot ROM correctly
identifies the clock speed, and the system runs rock solid...
Maybe you mean MHz? :-). Sorry, ads where sellers claim
spectacular milliHertz performance are one of my pet peeves. (Along
with specs calling for compatibility with the ASC-2 character set
and construction plans calling for DB-9 connectors!) Though it would
be an interesting exercise to construct a Pentium II-type computer
based on relays just so that it does top out around 300 milliHertz!
One thing I never understood about metric prefixes is how come
many of them are misused or, even more mysteriously, not used. For
example, everybody around the world uses the term "metric ton" when
the perfectly acceptable (and SI-preferred) term "megagram" is
exactly equivalent (and to my ears sounds better!) And why say
"ten thousand metric tonnes" when "10 gigagrams" is available?
Tim "but let's keep the Metric Buttload" Shoppa. (shoppa(a)trailing-edge.com)