🚀 go-pugleaf

In article <20767@cup.portal.com>,
 mmm@cup.portal.com (Mark Robert Thorson) writes [in part]...
>With regard to the pdp-11 and the -10, I recall a puzzling fact from the
>PDP-11 Peripherals Handbook.  Out of a large collection of peripheral products
>there was one which did not have "11" in its name.  This was the DL10
>Unibus window.

The DL10 was used to map the memory of the PDP-11 for use as communications
gear.  The DECsystem-10 could examine and deposit anywhere in -11 memory, and
it could also play with the -11's front panel through the DL10.  The -10 could
also allow the -11 to talk back to it.  This was done by assigning a part of
the -10's memory to appear in the -11's address space.  The assigned locations
could use the byte logic of the -10 to write to multiple addresses (or at least
bytes) in the -10's memory each time the -11 referenced them.  In fact, this
was part of the startup protocol for the nodes.  One of the first things they
did when they came on line was to tell the -10 what software they were running.

The DTE20 later 'replaced' the DL10.  It was simpler to maintain in the field,
and was much smaller.  I made up for this by being slower (at least for
networking applications).  The DTE20 is used by the console front-end (or
master -11) to load, dump, and diagnose the -10.  This is its only real
functional advantage over the DL10.  The DL10 almost never broke, but when it
did there were few people who ever wanted to try and fix it.  Its complexity
made it hard to debug the logic.

Actually, I know of at least one DL10 still in service at a current customer
site.  This customer has (so far) kept it because of its bandwidth advantage
for its networking.

Bias warning:  My duties at DEC include maintaining the native TOPS-10 network
software (ANF-10).  Our nodes will run fine through DTE20s, but they'd still
much rather be running through DL10s.  Other people might not be so supportive
of the DL10.

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