Home-made Bill-1

Home-made Bill-1

The Bill-1 computer is an Intel 8008 based computer that was originally designed and developed at Litton Data Systems in the early to mid 70s.  While not an official model, I call it the Bill-1 because that’s the name on the Litton Data Systems binder that houses the extensive documentation that came with it.  It also happens to be the first name of the person who, I believe, was part of the original design team and was the previous owner; William J. Stewart.

While the popular 8008-based computers of the time included the Mark-8 and Scelbi, the Bill-1 is not a variant.  These other systems are well documented in both their history and design and have a following of enthusiasts that have gone as far as recreating them in recent years.  This computer is is based on the Intel MCS-8 architecture as indicated in the documentation but has no known history.  It was not a consumer or hobbyist system but may a prototype computer for military applications (pure speculation on my part).

The documentation that came with it is extensive and includes schematics for each board,  wiring diagrams, circuit board layouts, board designs and parts lists complete with mil-spec part numbers.  Each board also includes extensive testing control documents.  All of this is in the binder marked “Volume 2”.  It is very clear that this was no “hobby computer”.  Unfortunately, “Volume 1” did not come with it but I would suspect that this missing volume may have specified the nature of this computer and why it was built.    It is referred to as a “CCU” or “Communication Control Unit” in it’s expanded form and lists some military projects in the hardware “change requests”.

The computer itself is made up of mostly printed circuit boards that were later acquired personally by Mr. Stewart as surplus boards from Litton Data Systems.  Additional  prototyping boards were also acquired in the lot with some being utilized for the creation of an unfinished front panel.

The computer is made up of a number of boards including:

  • One fully populated I/O control board
  • A second empty prototype I/O board
  • The main CPU board with Intel C8008 CPU and the supporting Intel C8201 that is believed to be a clock/interrupt controller chip.  This is a rare chip with it’s identification number being later reused by Intel.
  • A bread board with buffer chip
  • Two PROM boards with one fully populated by Intel C1702a EPROMs.  The other remains empty.
  • Four x 4k RAM cards to fill the RAM requirements of the c8008

The chassis is made up of 80 position card connectors that sit on a Vector Electronics frame.

There was a power supply in the lot that is believed to be for this computer that is made by Burroughs and is probably an off-the-shelf unit.  I can’t imagine it being made by Burroughs specifically for this prototype.

This computer will require further investigation.  The documentation includes sections for each of the individual boards but I’m not sure there is enough specific information to describe the bus and how each board interacts with each other.