View source for LSI-11/2

[[Image:KD11-HA CPU.jpg|thumb|right|350px|LSI-11/2 card]]

The '''LSI-11/2''' (also known as the '''KD11-HA''') is the later type of the [[LSI-11 CPUs]], using the same [[LSI-11 chip set‎]]. It contains only the [[Central Processing Unit|CPU]], and nothing else; it is otherwise identical in functionality to the [[LSI-11]], including the use of [[QBUS CPU ODT|ODT]], and it has the same [[QBUS]] limitations as the LSI-11.

It is a [[DEC card form factor|dual]] board (M7270); it supports all the same options as the LSI-11.

These include the [[KEV11-A floating point|KEV11-A]], for the [[PDP-11 Extended Instruction Set|EIS]]/[[FIS floating point|FIS]] instructions; the [[KEV11-B Extended Instruction Set|KEV11-B]], which provides EIS without FIS; and the [[KEV11-C Commercial Instruction Set‎|KEV11-C]], which provides a subset of the PDP-11 [[PDP-11 Commercial Instruction Set|CIS]] (it also apparently includes the EIS, but not the FIS).

The KD11-NA is an LSI-11/2 with the KEV11-A pre-installed.

The LSI-11/2 likely also supported the optional [[KUV11 Writeable Control Store]].

'''''Note:''''' The image in the "Microcomputer Products Handbook" (pg. C-18) is erroneous; the order of the chips (from the handle end) is, in fact, [[KEV11]], Control, uROM 1, uROM 0, Data Path (per the KD11-HA print set); the order given in the Handbook is that for the LSI-11 (no doubt an image was re-used without checking).

==See also==

* [[:File:M7270.jpg|Another LSI-11/2]] - Image; also without FIS chip

==Further reading==
	
* ''Extended Bus Time-out Logic'', [[MicroNote]] #032

==External links==

* [http://www.bitsavers.org/pdf/dec/qbus/Digital_Microcomputer_Products_Handbook_1985.pdf Microcomputer Products Handbook] - the LSI-11/2 is covered in Appendix C, pp. C-17&ndash;C-19 (pp. 609-611 of the PDF)
* [https://manx-docs.org/collections/antonio/dec/m7270.pdf M7270 LSI-11/2 microcomputer module user's guide]
* [http://bitsavers.org/pdf/dec/qbus/MP00706-ET-LSI-11_Dec81.pdf ET-LSI-11 Field Maintenance Print Set] (MP00706) - KD11-HA covered on pp. 131-137
* [http://web.frainresearch.org:8080/projects/pdp-11/lsi-11.php LSI-11 Processors] (mirrored [https://electrickery.nl/comp/pdp11_23plus/frain.rsx11m.io/lsi-11.php here])

{{PDP-11}}

[[Category: PDP-11 QBUS Processors]]
[[Category: DEC Documentation Errors]]