KM11-A Maintenance Set

The KM11-A Maintenance Set (also variously called the KM11-A Maintenance Panel, KM11-A Maintenance Console and KM11-A Maintenance Cards in some later DEC manuals) is a device used to perform maintenance activities on early PDP-11 CPUs and some early PDP-11 peripherals.

As produced by DEC, a KM11 consists of a W131 Maintenance Indicator Module plugged into a W130 Maintenance Connector Module; later a W131 and a W133 Driver Module. The W131 contains an array of 28 lights, three double-throw switches, and a single spring-loaded double-throw switch.

Overlays

A variety of overlays, specific to a CPU or peripheral, indicate the meaning of the lights, and the function of the switches, when used with that CPU or peripheral.

The CPUs which can use the KM11-A, and for which overays exist, are:

• KA11
• KB11 - all models
  • FP11-B/FP11-C (same inlay as CPU)
• KD11-A
  • KT11-D, KE11-E/KE11-F
• KD11-B (2 inlays)

Devices which support the KM11-A, and for which overays exist, are:

• RK11-C (2 inlays)
• RK11-D
• TM11
• RX01

There is also reportedly an overlay for the KE11-A Extended Arithmetic Element‎, but although several KE11-A documents refer to it, no image of it can be found.

Replicas

A replica KM11 from Shiresoft

The original DEC KM11-A's are incredibly scarce, but they are also a very powerful diagnostic tool. So, there have been several different projects to produce replicas; see the links below.

External links

• PDP-11/40 system engineering drawings - the KM11 is covered on pp. 123-125
• Maintenance Control Panel - DEC's original
• KM11 Replica - Guy Sotomayor
• Replacement KM11 maintenance board - Tom Uban
• How to build a clone of the DEC KM11 maintenance module - by Tony Duell
• DEC KM11 - Jörg Hoppe