On Tue, 11 Jan 2005, Eric Smith wrote:

> The KL10 always has an 11/40 console processor, which is connected to
> the 36-bit APR (Arithmetic PRocessor) via a DTE20 (Dec Ten/Eleven
> interface). The console processor runs RSX20F. During normal system
> operation of a DECsystem-10, it is only used for the console TTY
> interface, and to act as a system watchdog. On a DECSYSTEM-20, the
> console processor also is used as the interface to unit record equipment
> such as card readers, punches, and line printers.

Actually, the 11/40 FE was also the comm processor for all terminal lines.
That's partly why a KL was so sluggish when you instead had it on the net,
since the NIA-20 connected directly to the PDP-10 CPU, so all terminal I/O
had to be handled by the PDP-10 instead of offloading that to the PDP-11.

As for system watchdog, that was a real beaty. They both monitored each
other, and either could restart the other.

Not many stystems which could tell you that they weren't running...
%DECSYSTEM-20 not running

or whatever the PDP-11 said when it noticed that the PDP-10 had gone down.

> The KL10 can accomodate up to four DTE20s, so there can be up to three
> additional directly attached PDP-11 based I/O subsystems. These were
> normally DCxx or DNxx communication subsystems.

Love the hardware... :-)


Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt@update.uu.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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