View source for KDF11 CPUs

There are several single-board CPUs which all use the 'Fonz' [[F-11 chip set]]:

*[[KDF11-A CPU]] - M8186 - [[QBUS]] [[DEC card form factor|dual]]-width CPU used in the [[PDP-11/23]]
*[[KDF11-B CPU]] - M8189 - QBUS quad-width CPU used in the [[PDP-11/23_PLUS|PDP-11/23+]]
*[[KDF11-U CPU]] - M7133 - [[UNIBUS]] hex-width CPU used in the [[PDP-11/24]]

Like the [[LSI-11]] models, as a cost-reduction measure they do not have a front panel to control them; instead, when the [[CPU]] is halted, specialized [[microcode]] used the main serial line as a operating console. The command set is named Octal Debugging Technique (ODT); there are commands to read and write memory, start the CPU, etc. The main serial interface is normally configured so that when the CPU is running, sending a [[asynchronous serial line|break]] on the console serial line halts the CPU.

==Floating point==

All the KDF11 CPUs have two choices for floating point support (full PDP-11 [[FP11 floating point]]): a on-board single chip, the [[KEF11-A floating point chip]], which implements floating point using microcode; and a higher-performance separate quad board, the [[FPF11]] (M8188).

The FPF11 communicates with the KDF11 via a cable that plugs into the socket on the KDF11 where the KEF11-A is installed; is unusual that it can plug into either a QBUS or UNIBUS backplane, since it only draws power from the backplane - all signals come over the cable to the KDF11.

{{PDP-11}}

[[Category: PDP-11s]]
[[Category: DEC Processors]]