DEC RK11-C Disk Controller - on ebay...or is it?

Fritz Mueller fritzm at
Mon Feb 8 21:21:48 CST 2021

Yup, RK11-C, and it seems complete (modulo drive cables and terminators.)  I have one debugged and running in my '11/45, so I know it well.

> On Feb 8, 2021, at 3:16 PM, Ethan Dicks via cctalk <cctalk at> wrote:
> The ribbon cables are a bit out of place... perhaps they were just
> stuffed into empty slots to keep them from being damaged.

The cables are actually in the correct slots -- they connect A30 and B30 to the pass-through connectors to support plugging in a pair of KM11s from the outside of the rack for debug.

On nice thing about this controller is that it supports "Read/Write All" mode, which lets you read or write the raw bitstream including block headers.  This can be useful for disk recovery if you have a corrupted block header, or for reading/writing "foreign" disks (within limits).  This is controlled by bit 9 in the CSR, which is unimplemented on the later controllers.


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