DTE20 Ten-Eleven Interface

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The DTE20 Ten-Eleven Interface (also called the DTE20 Console Processor Interface) is a peripheral on KL10 CPUs which allows a PDP-11 to act as a front end. Depending on how the DTE20 is configured ('restricted' or 'privileged'), it can be just for off-loading I/O functionality to the PDP-11 (both to reduce the load on the main CPU, but also to allow access to the wide range of peripherals supported on the PDP-11); or it can also function as a control and diagnostic system for the main CPU: loading microcode, bootstrapping, etc.

The PDP-11 and KL10 are able to examine each other's main memory (in a limited way on the KL10 side, for restricted DTE20's), and interrupt each other.

A KL10 may have up to 4 DTE20's, and a PDP-11 may host up to 4 DTE20's on different KL10's.


The DTE20 is connected to the EBox of the KL10 via the EBus; privileged DTE20's also have access to the diagnostic section of the KL10's Ebus. To the PDP-11, it appears as a normal UNIBUS peripheral.

A 'restricted' DTE20 consists of a pair of hex boards (M8552, M8553) and a dual card (M8554), plugged into an I/O backplane of the KL10 (along with the RH20s). These are connected to a UNIBUS connector mounted lower down in that rack, and a BC11A cable from the PDP-11 (usually a PDP-11/40) plugs into that.

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