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manage and control the overall power consumption, and it can
even protect an electronic device from damage due to overheat-
ing or sudden power fluctuations or interruptions.
The MCM /70 power supply project might seem only a periph-
eral assignment compared to the major hardware and software
tasks at MCM , such as the development of the memory manage-
ment system or the design and implementation of MCM / APL .
But it was not. The MCM /70 was to be a small and portable
computer, and that constrained the size and weight of its power
supply. Traditional power supply designs of that time called for
heavy and large modules with one or more fans to remove the
excess heat generated by the electronic and other electrical com-
ponents of a computer. These power supplies were not very ef-
ficient either. Only sixty to seventy per cent of the energy that
entered such a power supply left it in a useful form; the rest,
converted to heat, was lost.
With a traditional design, to keep MCM 's computer small, the
power supply would have to be, for instance, taken outside of
the computer and hosted in a separate enclosure. The computer
would have to be connected with a special cable to the power
supply box in order to provide the various voltages required by
the computer's hardware. On the other hand, a built-in power
supply for a typewriter-sized MCM /70 would require the use
of new technologies to increase its power efficiency to as much
as 90 per cent. “The power supply was a big challenge,” com-
mented Laraya. Edwards' proposal for a small, highly efficient
power supply inside the computer was elegant and gained the
company's endorsement. “It was interesting,” continued Laraya.
“We were pushing the technology there using CMOS [Comple-
mentary Metal-Oxide Semiconductor technology]. CMOS was
in its early stages as well. Because being a portable machine, we
wanted a very low power dissipation.”
Edwards was initially instructed to build a simple but efficient
power supply. But very quickly new features were added to the
 
 
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