From DATATEKNIK, no 14 1996, page 67

The 36-bit machines are attacking

Is this really the moment to build a new, advanced multi-user machine today? Especially one that is founded on a stone dead engineering with the word length of 36 bits? That is anyway what a bunch of enthusiasts in the US are doing, and they plan to make money on the business.

The starting point for XKL, as the company is called, is Digital's mainframe DEC-20, which was cancelled in 1982. Many of those who used it then still think it was the most userfriendly computer built, and one of the most convenient to program.

XKL was founded in 1992 by Len Bosack, one of those who founded the computer communication company Cisco almost ten years earlier. He sold his part of the company in 1991, because he felt the company had grown too large, and ended up with a surplus of money.

- But I could not sit and only look at the Mediterranean, so I had to find something new to do. My new project was XKL, says Len Bosack.

Financing was no problem after having sold Cisco. But where to find the buyers?

- What we did when we started Cisco was to build a decently efficient router to a reasonable price. We found a small niche in computer communications. Now I wanted to do the same trick with a new computer design, says Len Bosack.

- It was obvious that computers have become faster, and communication devices better, but there is one exception: most computers still have disks which are a 100 times slower than the RP07 that was used in a DEC-20.

So there should, according to the reasoning at XKL, be a potential for a computer that to a reasonable cost gives a high I/O-capacity. Especially as I/O-intense applications like video on demand will increase in popularity. And the decision was to build such a computer based on the old 36-bit architecture from Digital.

At the beginning of June 1996 the development work was completed and XKL could announce its computer under the name Toad-1. The operating systems offered are TOPS-20 (the operating system for DEC-20) and a slightly reduced version of TOPS-10. The operating system is in addition Posix-compatible, and many unix programs can be run without changes in the source code.

- We knew that TOPS-20 was reasonably efficient. We also knew that there was a market for new TOPS-10/20 machines, as replacement for the old Digital ones. There is a number of such machines in service today, and they cost enormous money in power, service, space and cooling.

- But when we talked to Digital about buying the rights to TOPS-20 there was very few people who wanted to remember that they had sold those machines, tells Len Bosack.

The purchase price of a Toad-1 is about the same as cooling and power for running a DEC-20 during a year. Also important for the prospective buyers are that their staff knows the existing software, which can be used directly in the replacement computer. If the operating system and software has to be changed, the staff needs education, and the new system has to be run in parallell to the old one for a while. That costs time and money.

Compuserve in USA is one of the big potential customers, as their computers to a large extent are 36-bit machines. But XKL is also aiming at another possible market, which may well become larger than the market for replacing old machines. Toad-1 can be used as a file server for video on demand and other I/O-intense applications, and according to Len Bosack for a rather low total price for the capacity you get.

Besides the operating system XKL has ported various useful unix programmes, for example the text editor Gnu Emacs and the development tool make to the Toad. Also the X-client is included, which means you can log into the computer from your X-terminal or workstation. And more will come, says Richard Alderson, which is one of the developers at XKL.

- We will support Digitals networking protocol DECnet and it will be possible to use several processors. And a compiler for Fortran-77 is possible, it depends on what the customers want. We have however no plans for building clusters.

There is at the moment no swedish representative for XKL. But it can anyway be of interest for swedes to know that the operating system handles eight-bit characters; in fact it mostly uses nine-bit characters internally.


Jan Lien is a freelance writer with a large interest for old Digital computers.

XKL is located in Redmond, Washington. Phone +1 - 206 869 9050, fax 206 861 7863.

Joe Smith's private collection, SC Group (ex System Concepts),

Picture text:

- Computers have become faster and communication possibilities better, but there is still an exception: most computers still have discs which are a 100 times slower than RP07 which was used in the DEC-20, says Len Bosack, the old Cisco founder who is now building 36-bit computers after Digital's DEC-20.

[ Grey Box with picture ]

What does a TOAD-1 from XKL give?

The Toad-1 is an unbalanced computer, with far greater I/O-capacity than processor power. The basic configuration consists of a processor, one SCSI-2 card with four buses which can each connect 15 units, and an Ethernet card with four ports. But up to three more I/O-cards can be attached, and still run with one processor.

The backplane has a capacity of 250 Mbyte per second, and according to the manufacturer the machine will sustain full Ethernet speed at 16 connections with full throughput.

In the basic configuration 4 GB disc and 16 MWord (36-bit words, about 72 MB) memory is included. The price is around $100,000.

Service will be exchange of cards, which are later repaired at XKL. Toad-1 is built only with standard components.