Dual Systems Control Systems -- History
Dual Systems was founded in the late
1970's, during the heyday of the S-100 bus computers. It was originally
founded to produce a variety of peripheral boards (A/D and D/A converters,
serial interface boards, etc.). They came out with a 68000 CPU board for the
S-100 bus that was well received and so decided to specilized in the 68000
After a brief flirtation with CP/M-68K, they switched over to UNIX working
with a guy called Jeff Schriebman and his then new company
UniSoft Systems to
port the AT&T code to their system. UniSoft went of afterwards to redo
the code for many others such as Sun Microsystems, Silicon Graphics, Apple
Computer even Motorola itself.
Dual was unique in that it had used the S-100 bus as the basic backplane of
its original UNIX systems, when almost everyone else who followed used
Intel's MultiBus. Dual bought S-100 boards from
Morrow Designs, Macrotech,
and other well known S-100 design houses of that time. They also designed
its own SMD disk controller, a four port RS-232 serial controller, a Pertec
interface 9-track tape controller, DRAM and SRAM memory boards.
When Motorola announced the 68020, Dual decided to switch system busses from
S-100 to VME (a Motorola bus design; 32 address and data lines, can do 8,
16, or 32 bit transfers), and to design a multiprocessor UNIX system. The
VME bus was faster than the S-100, and was better suited to multiprocessor
and multiple bus-master systems than even the Intel MultiBus II. It
was also clear that the S-100 bus was reaching the end of its design life.
Dual successfully designed a new CPU board around the 68020 with 512K of
DRAM right on the board (VME boards are 20% bigger than S-100 boards, and do
not require power regulation right on the board since bus power is regulated
However Dual did not keep up with the market, they never produced a system
with a graphics console - just a computing box for use with terminals. In
the end, Dual was acquired in the late 1980's by
Northstar, and their
technology was sold off to whatever interested parties could be found.
Right from the start Dual made a decision to go after the high end/commercial
market. They ended up with an extensive line of S-100 boards as can be seen from
their catalogue. However their
systems were very expensive.
Complete systems ranging from $17,000 up to over $65,000. Clearly commercial
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