All Terrain Thinking

A Compendium of things I think are Important

Historical Perspective on Today's' PC

Memories of Burroughs

These (edited) memories have been contributed by visitors to this web site.

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I loved your website.

I worked as an "FE" at Burroughs from 12/75 till 6/81. There was two Group classifications of Field Engineers at Burroughs-- Group II and Group III. I belonged to Group II and we handled all Group I (Calculators, mechanical adding machines, Sensimatics and the like) and Group II which included the "Mini-computers" (L/TC's), B700/800/900 and B80/90 Burroughs hardware. The Group III engineers did hardware maintenance on the larger B1700, etc product line.

I have one correction to the L8000 section. You stated: "It was also equipped with a faster 40 character-per-second dot matrix printer (or "needle printer, as it was called)." All L8xxx models had the "ball printer". The 20cps printers were controlled with the use of the "oil filled decoder" which contained the tilt and rotate mechanism / relays to drive the "bands" that operated the print ball. Later versions of the L8xxx had the 30cps printer, which incorporated separate stepping motors for the tilt and rotate functions. The 30cps L8 models failed regularly due to driver transistors burning out and mechanical timing slipping. The dot matrix printer was released with the L9xxx series. It was somewhat superior to the L8, but had problems with the ribbon dot matrix cable shorting and the needles being bent due to paper jams, etc.

The B700 was also challenging to support / maintain. The "CPU" was solid, even the early "core memory" models. Most service calls were to fix the B9480/81 removable disk drives. The 100 track per inch drives were generally maintenance free, unless the heads crashed, however the 200tpi models never really worked in my opinion. These included temperature compensations circuitry that always needed adjustment and failed regardless of how they were adjusted. They had a servo positioning motor to position the "heads" that ran on rails and would become "gouged" over time from dirt and usage. Once this happened, the only solution was to replace them and try to align the replacement rail so it could read all the customer's existing media. Of course, you didn't leave the customer sight until you verified you could read all their disks after the operation, or you were back the next day by popular demand.

The B800 line was even better than the B700. It had an "Electronic" eight channel paper tape reader feeder as opposed to the "Mechanical" reader on the B700. This saved a ton of time when it came to loading maintenance paper tape programs to diagnose CPU issues. It used the same "FE Cards" that were plugged into the CPU that allowed for manual step though the maintenance programs. Based on a halted led register pattern, a list of IC's was presented for replacement spread among some 25+ 8 x8 in printed circuit cards. All "chips" were plugged into removable sockets, so FE's usually carried a box of 50+ different 14 pin chips that could solve all their problems :-)

The B900 was the last model in this product line. The biggest difference in this model from the B800 was the ability to assign different functions to different CPU's. For example, your could assign Data Comm or Printing to one CPU set. Additionally, MPLII or COBOL applications could be dedicated to one or more CPU set(s).

My six year stint at Burroughs was a learning experience to say the least. It was a time when support involved technical skills. Mechanical skills were necessary to repair old F and E Series Sensimatics. There were transistors to be physically replaced in the L/TC line; there was no surface mount technology. There were voltages to be measured and set accordingly to operational tolerances. There were disk heads to be aligned using "tri-bit / cat-eye" patterns as viewed from your Model 422Tektronix scope. Ah, the good ole days!

Thanks and keep the Burroughs page up,

Steve Svoboda
Salt Lake City, UT

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Last modified:23 December 2011

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