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Early History of SDS

Contributed by Tim Stradtman

Sierra Data Sciences was a small group of geeks that happen to be in the right place at "almost" the right time.  SDS actually started as a retail outlet for the just beginning hobby computing industry in about 1977.  The owners, established corporate IS programmers, licensed a franchise from The Byte Shop chain of stores.  The Byte Shop was similar to Radio Shack, however they focused on the newly emerging micro computer market.  Byte Shop of Ohio was located in Fairview Park, Ohio (a suburb of Cleveland).  Byte Shop eventually collected a group of people that were interested in home and small business computing together, myself included.  There were several business people, a couple of Case Western engineering students (the real talent behind the company), some mainframe programmers that would freelance in the micro world, and a few technicians that would assemble and test the kits.  A lot of the sales at the time consisted of buying a kit, building and customizing it then reselling it in the retail store.  A lot of soldering in those days.  I think that someplace I still have the Polymorphic 88 that I built but was never sold.  Many times the real challenge was to figure out what the designer really did, rather than what the limited documentation said (we had tons of copies of manuals with notations like "This chip is backward in the picture - Put it in the way shown here and it will fry"). 

Another part of the business was mainframe consulting to a credit card processing center in the area.  As part of this consulting, we developed what would now be known as a network switch, but using telephone lines and modems rather than Ethernet.  To do this we needed more than the one or two serial ports available on most S-100 systems at the time.  Add-in cards at the time generally only added two ports and were hardwired so only one add-on card could go into a system. So we came up with the SIO-4.  It was a 4 port serial card that was configurable with jumpers so that up to 8 cards could be in a system at the same time, giving 32 serial ports.  These cards were used initially only for the credit card processing systems, but there were some outside sales due to ads in BYTE magazine. 

About this time, the "Byte Shop" franchise was sold to an outside investor who was essentially an "out of town landlord".  At the time, we had begun work on a Single Board Computer (SBC) using the S-100 format. We approached the new owner with a proposal that if he funded the SBC development, he could have a percentage of the "rights" to the new SBC board and also 90% of the "rights" to the then rather popular SIO-4 product (our staff had added 4 full time assemblers by this point, and still could not keep up with the demand).  His response was "You can keep 100% of the rights, because 100% of zero is still zero", and refused to fund the SBC.  Essentially the entire team resigned on the spot.  They then "relocated" the entire operation to Fresno, which is where one of the previous Byte Shop owners had moved.  "Relocated" is quoted because I was the only person that actually moved, everyone else had family in the Cleveland area and simply spent about a year away from their families.  I was single at the time and did not have those perceived limitations.  The logic behind the move was that west coast was hot (the term "Silicon Valley" was yet to be coined), and the new company's name was Sierra Data Sciences, named after the Sierra Nevada Mountains near Fresno.  The SBC-100 was completed and ready for market, and was touted as the first truly single board computer. 

It had:-

  • Z80 processor - Could be run at either 2 or 4 MHz, although I don't recall actually selling any 2Mhz boards, the default was 4Mhz.  We had a few at the office running 2Mhz, primarily because some batches of CPU chips were unreliable at 4 MHz, but worked OK for internal use at 2Mhz.

  • 128K RAM - Used some I/O ports to bank portions of memory in and out to get around the 8080/Z80 64K limit.

  • Two Boot ROM/EPROMs - Booted into a monitor/load program, CP/M or TurboDOS.  There was an option to make one of these locations burnable

  • Floppy disk interface

  • A fully bidirectional parallel port - Ended up being used as the primary hard disk interface, it was almost SCSI.

  • Two serial ports up to 38.4K bps

There was an SDS expansion bus on the top of the card, configured as a ribbon cable that was daisy chained between boards. This was designed to allow extended access to other cards outside the S-100 design.  The Master and Slave boards could communicate through this bus faster than the S-100, and it also had memory mapping ability.  It had great potential, unfortunately the software to use was never fully developed beyond the lab and a single test site,  ISTR that this was deprecated in later versions (the traces were still there, but the area was not cut out for a connector and it was not gold plated).

The first version of the SBC available was the "Master" SBC, it was a complete system on a single board.  The only thing required was I/O - a serial terminal and/or modem and optionally a disk of some kind.  The board was even designed so that you did not even need a full S-100 bus, there was a way to set up the power section so that you only needed a 4 prong power connector.  Ironically, the connector chosen for this option ended up being the same physical connector that was eventually used in almost all 5 1/4 hard disk drives, although I think the pinouts were different.  The second version was the "Slave" SBC.  It was essentially the same board, but it lacked the floppy disk interface, only had 64K of RAM, and a single non-programmable ROM location.

At this point in time, orders start coming in fast and furious.  We were considerably understaffed and underfunded for the demand.  Since the entire team was from the Cleveland area and had connections with manufacturing in Cleveland, the decision was made to move everything back to the Cleveland area.  Everyone and everything moved back to a warehouse that was previously a gymnastics training center in Westlake, Ohio.  Essentially the entire company was hired at this time (many using informal Friend-of-a-friend connections), at one point there were about 30 people in the company.  Work continued on developing new products, several types of enclosures were designed to house the SBC as a complete system with a monitor, printer etc., an "appliance" type box that would be connect to a terminal long enough to set up then run unattended, various disk add-ons...

There were two operating systems that were shipped with these systems, CP/M and TurboDOS.  I did a ton of work getting the TurboDOS systems ready. TurboDOS was about 10 years ahead of it's time, it had some excellent features that did not show up in mainstream products for years.  In addition to the initial driver level development, I did a fair amount of production management and quality control on the factory floor.

One of the things that always plagued SDS was cash flow.  It was a small company with an excellent idea that had grown way too fast.  There were two incidents that I feel caused the demise of SDS.  Sometime in the summer (need to figure out exactly what year, about 1983), there was a break in at the company, with some suspicious aspects (alarms never went off, an employee's vehicle that was (for an unknown reason) parked inside the building was also taken).  The physical material stolen was not overly large, but extremely significant with regard to  production - CPUs and memory chips.  At the time we were stretched to the limit with our suppliers and behind on orders.  Because of the suspicious nature of some of these issues, the insurance company made an extremely through investigation, which took a lot of time.  Meanwhile, we cannot ship all orders because we are missing a single part (usually the CPU). 

A couple of months later, there was a very similar break in with similar products stolen.  SDS never recovered and shortly after the second break-in closed forever.