Silicone on Sapphire

[BillCRAV]

(03-13-2016 06:53 PM)jebem Wrote:  If you read the above statement carefully, you will see that there is no mention to the RCA 1802 processor. The article's author just mention "RCA-built SOS
microprocessor " without going to deep details.

We cannot imply from his words that he claimed that a 1802 was used in the Voyager.

Additionally, the article author is an accredited person working on SOS technology since the NOSC era, so I have no reason to doubt his words.
Here is the information extracted from that article::
George Imthurn is a Device Engineer for Peregrine Semiconductor
Corporation, a manufacturer of UltraCMOS-based RFICs. During
his tenure at Peregrine he has contributed to the basic understanding
of SOS and worked on improving the radiation hardness of the
UltraCMOS process. Before joining Peregrine he worked on SOS at
the Naval Ocean Systems Center. George received his BS at Pacific
Union College and his MSEE at San Diego State University. His
thesis work was on guided wave optics.

True about his implication. More or less. Kind of, but it partly depends on definitions, and interpretations.

Also, his particulars do not mean that he cannot make a mistake, misremember, misspeak, and/or be misquoted.

The only "RCA-built SOS microprocessor" at that time (I'm pretty sure ever) was the CDP1802,
which came to fruition too late to be used in the Voyager spacecraft (I & II), but was around to be used in the later Galileo.

It could depend on your definition of "microprocessor", which generally refers to a single-chip
integrated circuit, but could also mean "a few ICs".

For example, from Wikipedia: "A microprocessor is a computer processor that incorporates the
functions of a computer's central processing unit (CPU) on a single integrated circuit (IC),
or at most a few integrated circuits."

It is known from the specifications that the Voyagers used the rad-hardened versions of the 4000 series ICs
(CMOS/low power), which were NOT "highly integrated", and so it required that MANY IC's be used to
create a computer system with them.

They were "simple" function IC's that included adders, analog switches, buffers, counters, flip-flops,
latches, logic gates, multiplexers, demultiplexers, encoders, decoders, shift registers, timers,
translators, and 7-segment decoders.

None of which come close to being a "microprocessor", but which can be used to build one, although,
again, it would take MANY of them, not just a few. So it would be better-termed a "computer" or "microcomputer".

Also from Wikipedia: "It has been erroneously reported on the Internet that the Voyager space probes
were controlled by a version of the RCA 1802 (RCA CDP1802 "COSMAC" microprocessor), but such
claims are not supported by the primary design documents. The CDP1802 microprocessor was used
later in the Galileo space probe, which was designed and built years later. The digital control electronics
of the Voyagers were not based on a microprocessor but on a specially designed set of RCA CD4000
radiation-hardened, silicon-on-sapphire (SOS) custom-made integrated circuit chips, combined with
standard transistor-transistor logic (TTL) integrated circuits."

So the wording of "RCA-built SOS microprocessor" is actually incorrect, because RCA did not
build the "microprocessor" (afaik), but their components were used in its construction.

Of course, much of the documentation and history has been lost, so who knows how instrumental RCA
was in working with the Voyager team(s). it is possible that they "built the system" from specification,
but in my fairly exhaustive research on the subject, i have found no information regarding that reality.
And that would have been something to be proud of and proclaim, since it would have been a HUGE feather
in RCA's cap, instead of just their components being used, which was also a nice feather in its own right.