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Based in Redmond, Washington XKL, LLC, was founded in 1991 and develops optical transport technologies.[1] XKL is led by Cisco Systems co-founder Len Bosack who also used to work for DEC and Bell Labs. Under Bosack, Cisco commercialized local area network (LAN) technology to connect geographically to computers over a multiprotocol router system.

Industry Telecommunications
Optical networking
Computer Networking
Founded 1991; 27 years ago (1991)
Founder Len Bosack
Headquarters Kirkland, Washington, U.S.A
Area served
Key people
Len Bosack and Sandra Lerner
Products Darkstar Optical Network Hardware


History of XKLEdit

In its earliest days, XKL built a compact, modern replacement (TOAD-1) for a massive mainframe computer system (PDP-10) that had gone out of production. The challenge at the time was to find a mainstream usage for a totally new technology: a platform with a desktop-sized footprint, but incorporating technology that would bring the system into the 21st century.[2]

XKL deployed DarkStar technology that allows enterprises to take advantage of higher reliability and allow for more control over IT resources at a lower cost. The “plug and play” system allow data network engineers to deploy their own optical transmission systems in metro, regional and long distance networks.


TOAD-1 unit on display at the Living Computer Museum in Seattle, WA


The TOAD-1 System, also known as TD-1,[notes 1] was announced in 1993 and built as an extended version of the DECSYSTEM-20 from Digital Equipment Corporation. The original inspiration was to build a desktop version of the popular PDP-10 and the name began as an acronym for "Ten On A Desk". It was eventually built at XKL by veteran engineers from Cisco, DEC, Hewlett-Packard, and CDC.[3]

XKL TOAD-2 on display at the Living Computer Museum in Seattle, Washington.
Full view of the XKL TOAD-2 on display at the Living Computer Museum in Seattle, Washington.

It was the first XKL product produced and it became available for purchase in late 1995. The TOAD-1 is a high-performance I/O oriented system with a 36-bit processor running TOPS-20. It is a 36-bit multi- user system that can provide service to over 100 users at a time. The TOAD-1 architecture incorporated modern peripherals, and open bus architecture, expanded physical and virtual memory while maintaining the TOPS-20 user environment.[1]


The TOAD-2 was built to replace the TOAD-1. It was a single chip reimplementation used as redundant control processors in networking equipment from XKL. It could be configured for TOPS-20 timesharing.[3]

Darkstar DXMEdit

First released in 2007, the Darkstar DXM was a high-performance optical switch first installed at the California Institute of Technology as part of their Supercomputing Bandwidth Challenge. It provided 5 times the bandwidth, in excess of 100 Gigabits/sec, than the existing system but was also smaller and used less power.[4]


  1. ^ The TOAD-1 was referred to as the TOAD as a development codename and then changed to the TD-1 as the original marketing name. It was then swtiched back to TOAD-1 before production began.


  1. ^ a b "XKL Flier". Retrieved 29 June 2016. 
  2. ^ "About Us – XKL". 
  3. ^ a b "Exhibits - Living Computer Museum". 
  4. ^ "XKL, LLC: XKL Supports Caltech in Supercomputing '08 Bandwidth Challenge". Internet Archive: Wayback Machine. 6 October 2009. Archived from the original on October 6, 2009. Retrieved 12 July 2016. 

External linksEdit