Scientific Data Systems

Scientific Data Systems, or SDS, was an American computer company founded in September 1961 by Max Palevsky, a veteran of Packard Bell and Bendix, along with eleven other computer scientists. SDS was an early adopter of integrated circuits in computer design and the first to employ silicon transistors. The company concentrated on larger scientific workload focused machines and sold many machines to NASA during the Space Race. Most machines were both fast and relatively low priced. The company was sold to Xerox in 1969, but mismanagement and dwindling sales caused Xerox to close the division in 1975 at a loss of hundreds of millions of dollars. During the Xerox years the company was officially Xerox Data Systems, or XDS.

History

Throughout the majority of the 1960s the US computer market was dominated by Snow White (IBM) and the Seven Dwarves, NCR, Burroughs, Control Data Corporation, General Electric, Honeywell, RCA and UNIVAC. SDS entered this well developed market and soon carved out their own niche, a surprising development. Much of this success was due to the use of silicon-based transistors in their earliest designs, the 24-bit SDS 910 and SDS 920 which included a hardware (integer) multiplier. These are arguably the first commercial systems based on silicon, which offered much better performance for no real additional cost. Additionally the SDS machines shipped with a selection of software, notably a FORTRAN compiler, developed by Digitek, that made use of the systems' Programmed OPeratorS (POPS) and could compile, in 4K 24-bit words, programs in a single pass without the need for magnetic tape secondary storage. For scientific users writing small programs, this was a real boon and dramatically improved development turnaround time.

The 910 and 920 were supplanted by the SDS 9300, announced in June 1963. Among other changes, the 9300 included a floating point processor for higher performance. The performance increase was dramatic, the 910/920 needed 16 microseconds to add two 24-bit integers, the 9300 only 1.75, almost 10 times as fast. The 9300 also increased maximum memory from 16 kWords to 32 kWords. It was otherwise compatible with the earlier machines.

In December 1963 they announced the SDS 930, a major re-build of the 9xx line using ICs in the central processor. It was comparable to the 9300 in basic operations, but was generally slower overall due to the lack of the 9300's memory interlace capability and hardware floating point unit (although a hardware floating point "correlation and filtering unit" was available as an expensive option). The 930 cost less than 1/2 that of the original 9300, at about $105,000. Cut-down versions of the 920 also followed, including the 12-bit SDS 92, and the IC-based 925.

A project to develop a segmentation and relocation system for time sharing use at the University of California, Berkeley resulted in the SDS 940, basically the 930 with additional hardware to provide relocation and swapping of memory sections, and interruptible instructions. The 940 would go on to be a major part of Tymshare's network system growth in the 1960s. A 945 was announced in July 1968 as a modified 940 with less I/O but more compute power, but it is unclear whether this shipped. The 945 never shipped; I had the one-and-only 945 stainless steel bar. I think it was actually just like the 940 but with a smaller drum in place of the disc.

In December 1966 SDS shipped the entirely new Sigma series, starting with the 16-bit SDS Sigma 2 and the 32-bit SDS Sigma 7, both using common hardware internally. The rise of the 8-bit ASCII character standard was pushing all vendors to the 8-bit standard from their earlier 6-bit ones, and SDS was one of the first to enter this market. Various versions of the Sigma 7 followed, including the cut-down Sigma 5 and re-designed Sigma 6. The Xerox Sigma 9 was a major re-design with instruction lookahead and other advanced features, while the Sigma 8 and Sigma 9 mod 3 were low-end machines offered as a migration path for the Sigma 5. The Sigma range was very successful in the niche real-time processing field, due to the sophisticated hardware interrupt structure and independent I/O processor.

Even with these successes, when Xerox bought the company in 1969 they sold only about 1% of the computers in the US, something Xerox never seemed to improve. When they were purchased, about 1,000 SDS machines of all types were in the market, and by the time the division closed in 1975 this had increased to only about 2,100. By this point the newer Xerox 550 and 560 models, extensively re-designed Sigmas, were about to come to market and were extensively back ordered. Most rights were sold to Honeywell in July, 1975 who produced Sigmas for a short period, and provided support into the 1980s.

Several manufacturers attempted to enter the Sigma 9 replacement market. The first successful design was the Telefile T-85, but it is not clear how many were sold. Other efforts, including the Modutest Model 9, Ilene Model 9000 and Real-time RCE-9 were designed, but it is not clear if they were ever produced past the prototype stage.

A new start

In 1979 Jack Mitchell, William L. Scheding, and Henry Harold, former SDS engineers, along with some other ex-SDS people re-started the company with funding from Max Palevsky, Sanford Kaplan, Dan McGurk, and others. They introduced a microprocessor based computer called the SDS-420 built on a 6502A-based processor design with up to 56KB of memory and a proprietary OS, SDS-DOS, along with the BASIC programming language produced by upstart Microsoft, Inc. The SDS-420 featured a dual single-sided-double-density (400KB per side) floppy drive, Model 70, manufactured by PerSci (Peripheral Sciences), of Santa Monica and Marina Del rey, CA. The SDS-422 Model offered some of the first dual double-sided-double-density floppy drives. Other hardware options were a 6551-A USART and a proprietary network SDS-NET using an 8530 SDLC/HDLC chip and software patterned after the early Xerox 3.0 Mbit/s ethernet and tranceivers produced by Tat Lam of the Bay Area.

The 400 Series had little to do with scientific computing and more with word processing and business services. The company sold about 1000 machines worldwide, including Tahiti, London, Italy, New York City and Los Angeles.

SDS announced at COMDEX, in the early 1980s, its SDS NET a fully operational local area network (LAN) based file server (Model 430) (written by Sam Keys, of Westchester, CA). The SDS-430-Server offered file and print-sharing services over SDS-NET or modems and was based upon a 10MB hard disk manufactured by Micropolis of Chatsworth, CA. SDS Offered other models, including the SDS-410, a diskless work station that booted and ran off the SDS-NET or optionally could boot off-of and run over a 1200 bit/s modem link.

Producted offered were: Word (word processing, written by John McCully, formerly of Jacuard Systems, Manhattan Beach, CA.), and fully-functional accounting software: balance-forward and open-item accounting with GL, AR, AP, & Payroll (written by Tom Davies and Sandra Mass, both formerly with Jaquard Systems).Other offerings included: Legal Time and Billing, Medical Time and Billing, and TTY an early terminal emulation program using the 6551 USART. Through partnerships with their VARS (Value Added Resellers) other software product offerings included a solid-waste management system with automated truck routing and a country-club accounting package.

Production of a clone was started in England in 1983 due to financial problems at SDS.

The second incarnation failed, and the new SDS went out of business in 1984.

Known users

Although initially intended as a Scientific Computer System, the Sigma series and the 900 series was used extensively as a Commercial Time Sharing System. The biggest such user was Comshare Inc, Ann Arbor, MI who extensively developed the hardware during the 1980s and the Sigma 9 was operated commercially until approx 1993. Developments and improvements by Comshare included the I-Channel which allowed the utilization of Bus/Tag (IBM compatible) devices and the ISI Communications interface. These innovations allowed Comshare to capitalize on the Sigma CPU's and their software development (Commander II) by gaining access to current technology storage systems.

Other known users outside the U.S. include:
* British Airways (Sigma 2 & 3 - Flight Simulation)
* Link Simulation (Lansing)
* WS Atkins Engineering (Epsom)
* British Aerospace (Wharton)
* Comshare (London)
* Cybernetic Research Council (Slough)
* Rank Xerox (Denham)
* Rank Radio International (Plymouth)
* Royal Naval Engineering College (Manadon)
* Warwick University
* Addenbrookes Hospital (Cambridge)
* Charing Cros Hospital (London)
* University College Hospital (London)
* St. Thomas Hospital (London)
* Government Chemist
* A&AEE Boscombe Down
* Aeritalia Turin
* MBB Munich
* Sonatrach (Algeria)
* American Israeli Paper Mills (Israel)
* Israeli Navy
* IAF Aircraft (Israel)
* AKU Studsvik (Sweden)
* West Chester University

DS Software

The primary operating system for the 900 series was called Monarch. For the Sigma 32-bit range RBM, a real-time and batch monitor, and BTM, a batch and timesharing monitor were available. In 1971 a more sophisticated timesharing system UTS/XOS was released, which was developed into CP-V. The RBM operating system was replaced by CP-R, a real-time and timesharing system.In March 1982 Honeywell gave the remaining software for the 900 series to a group in Kansas City that offered to continue making copies for people still using the systems. Honeywell had stopped supporting the systems many years before this. In September 2006, this collection was donated to the Computer History Museum along with all of the program's originaldocumentation, and copies of most of the SDS user's manuals. This is one of the largest collections of software to have survived from the 1960s intact. Unfortunately, the timesharing software for the 940 series was not present in the Honeywell LADS Library and does not appear to have survived. Copies of the original system developed at UC Berkeley exist as file systembackups. Most of the customers for 940 systems (in particular Tymshare) made extensive modifications to the 940 system software, and no copies of that version of the software are knownto have survived.

A simulator for the Sigma series is known to exist, and Sigma series software is being collected by the Computer History Museum. Early versions were not copyrighted (CP-V C00 and earlier), while later versions developed by Honeywell were (CP-V E00 and F00). Some copies of CP-V D00 were released without licensing agreements and subsequently public domain status was claimed by users.

Computer models

* SDS 910 - first design, shipped along with the 920 in August 1962
* SDS 920
* SDS 9300 - high performance 920 with FPU and more memory
* SDS 92 - 12-bit "low end" machine
* SDS 925 - less expensive but faster 920
* SDS 930 - major redesign
* SDS 940 - 930 with additional support for time sharing
* SDS Sigma 9
* SDS Sigma 7
* SDS Sigma 5
* SDS SIgma 3
* SDS Sigma 2
* Sigma 530

ee also

*Berkeley Timesharing System

External links

* [http://www.cbi.umn.edu/oh/display.phtml?id=355 Oral history interview with Paul A. Strassmann] Charles Babbage Institute, University of Minnesota, Minneapolis
* [http://archive.computerhistory.org/resources/text/SDS/SDS.Sigma.1967.102646100.pdf Scientific Data Systems The Sigma Family: Introducing Sigma from Scientific Data Systems. 1967]
* [http://www.andrews.edu/~calkins/profess/SDSigma7.htm SDS Sigma 7 technical information]
* [http://bitsavers.org/pdf/sds/9xx SDS 900 series documentation at bitsavers.org]
* [http://bitsavers.org/pdf/sds/sigma Sigma series documentation at bitsavers.org]
* [http://bitsavers.org/pdf/sds/tymshare Tymshare documenation at bitsavers.org]