View source for KT24 UNIBUS map option

[[Image:KT24.jpg|300px|thumb|right|KT24 board]]

The '''KT24 UNIBUS map option''' is an option for the [[PDP-11/24]] which provided a full path between its [[UNIBUS]] and [[Extended UNIBUS]] (EUB) via a [[UNIBUS map]]. It also provided a number of other facilities, including [[chip socket]]s for a [[bootstrap]] [[PROM]] set (compatible with those of the [[M9312 ROM|M9312]]), and a [[power supply]] [[voltage]] monitor for the system. The KT24 was implemented as a single [[DEC card form factor|hex]] [[printed circuit board]], the '''M7134'''.

==UNIBUS map details==

The KT24 had standard UNIBUS map functionality; a set of 31 mapping [[register]] pairs in the KT24 mapped 8 Kbyte blocks of UNIBUS [[address space]] to any location within the 4 Mbyte [[main memory]] [[address space]]. A pair of [[jumper]] sets could limit the range of UNIBUS address space which was mapped; a control bit in the KT24's Last Mapped Address [[register]] causes the jumpers to be ignored, for [[diagnostic]] purposes.

If no KT24 was present, the [[Central Processing Unit|CPU]] detected its absence, and turned on a set of drivers on the CPU card which gated the [[address]] from the UNIBUS through to the EUB. (Pin FE1 of the CPU slot, "UB to MA VIA UBMAP", is connected to a pull-up on the CPU board, and also runs to the slot where the KT24 is plugged in, where it is grounded if a KT24 is plugged in; that signal is used to generate "UB to MA", which is the cross-connection enable signal.)

==External links==

* [http://www.bitsavers.org/pdf/dec/pdp11/1124/EK-11024-TM-001_PDP11_24_System_Technical_Manual_Jun81.pdf PDP-11/24 System Technical Manual] - the KT24 is covered in Chapter 6 (pp. 162-174)
* [http://www.bitsavers.org/pdf/dec/pdp11/1124/MP01029_KT24_UNIBUS_MAP_SCHEMATICS.pdf KT24 Unibus Map Option Field Maintenance Print Set] (MP01029)

[[Category: UNIBUS PDP-11s]]
[[Category: Extended UNIBUS]]