It’s All About Power - Inventing the PC - page 103

show. The very survival of MCM hinged upon DDC 's volume
sales of MCM /70s. In general, the DDC salesmen were enthusi-
astic about the machines; some of them took the MCM /70s to
their hotel rooms to play with overnight. However, the number
of power-supply-related failures during the show was alarming.
Furthermore, DDC informed MCM that barely three days after
the show “unit no. 4 (which, incidentally, was claimed to have
the 'best' power supply), was down because of a blown power
supply. Smoke came out of one of the coils … Unit no. 7 was
down because it kept on blowing fuses.”
On 24 September, several employees, including Laraya and
Rea, wrote a report on the status of the power supply and its
impact on the company's survival. In the document, the authors
reported that Edwards' “clean-up” of the power supply not only
missed the 12 September deadline, but also that “The 'clean-up'
referred to in the 16 August memo turned out to be a redesign
of the controller.” The authors complained that “there is no
complete documentation on why changes were made and what
problems these changes were supposed to solve.” (It is surpris-
ing that MCM was unable to institute and enforce such require-
ments for all its research and development activities.)
But that was not the end of the critical report. The authors
pointed out that the “switching inverter techniques used by Mr.
Edwards had already been published by Motorola in many of
their Application Notes in 1972 and also by Electronics maga-
zine in 1973.” According to the authors, “these were not taken
advantage of.”
The report also quoted the opinion of Power Conversion Sys-
tems Ltd ( PCSL ) which was critical of MCM 's switching power
supply. Apparently, even if PCSL agreed to manufacture these
advanced power supplies designed at MCM , PCSL would be
unable to provide a guarantee for them. PCSL informed the au-
thors of the report that they had experience with these types of
power supplies and that it would take the company approxi-