NEED
A new Extended Industry Standard Architecture (EISA) bus
computer market was defined by Compaq, Olivetti, AST, Hewlett Packard and
others. These computers were to be used for high speed file servers and
workstations, and required new high speed disk, tape, and printer controllers.
Companies that built all new controllers would miss the market window.
With the new controller, the new EISA computer was expected to
handle 256 users instead of the original 45.
Our client had an asynchronous VME bus design already in
production that had similar functions required by EISA. A UNIX software driver
and on-board firmware also existed. The client required that any changes in the
card allow it to use existing software as much as possible.
The client also required that the product be ready in time for
an important trade show. There was not enough time in the schedule to build a
wire-wrap prototype. Also, the target computer, which was based on the 80486
chip from Intel, would not be available until the very end of the project.
SOLUTION
The existing schematics were compiled on a Computer Aided
Engineering (CAE) workstation, digital simulation was used, wave forms were
plotted and analyzed, and corrections were made. After modifications were made
to the bus interface, a new synchronous state machine was implemented using
programmable logic devices (PLD).
A new section of 80486 code was added to the 68020 firmware,
allowing the system to boot from disk.
RESULTS
The final design was a 10-layer surface-mount and through-hole
PCB design. Dozens of circuit cards were manufactured and assembled, and
preliminary testing was done while the anxious wait for the new EISA computer
continued. Finally, the wait was over. With only a few weeks remaining for final
testing before the trade show, minor medications were made and the product was
ready for production.
