[time-nuts] the logic versus cpu equation

[walter shawlee 2]

I always marvel at the argument that a $1 CPU can out-perform a bag of logic 
which will be "more expensive". this is such utter hogwash, I really felt I had 
to comment.

this view assigns zero cost to the software, development (IDE), programming, and 
support of the code, a cost that dwarfs the hardware cost by many orders of 
magnitude. furthermore, testing and validation of the code is not trivial, and 
it is quite common for uncorrectable timing errors to surface due to device 
archtecture.

further, this design cannot be readily duplicated, making sharing of the effort 
very awkward. the world is littered with abandoned software designs which fall 
into disuse for this very reason. not to mention 18 month obsolescence cycles 
for microprocessor parts. it aways sounds so simple to "just email the code".
but what happens 5 years later?

in addition, the integrity of the design is fundamentally uncertain, as ALL 
programmed parts fail, sometimes within a short window. data retention is often 
brief (5 years, almost never over 20 years, and easily upset by static 
discharge, read cycles, elevated temperatures, radiation and other factors)  
there is *no such a thing as durable code*, it is always a transient design 
element. those who believe otherwise have simply failed to read the giant stack 
of device datasheets that clearly spell this out.  as NAND flash users in server 
farms are quickly learning, drives based on this technology have much higher 
failure rates than mechanical magnetic storage, and the extensive published data 
is quite compelling.

a design based on hard wired logic always works as intended, and is easily 
maintained in the event of device failure. this is simply not true with any 
microprocessor, gate array or pal based solution. never forget that the 
programmed part IS NOT an off the shelf item. the amount of high tech gear 
currently being trashed because of data corruption is staggering.

this problem has surfaced in so many areas of technology from cell phones, test 
equipment to environmental controls, it simply makes my blood run cold to hear 
the fiction of "software designs work so much better than hardware" repeated 
without at least a word from the opposing view.

I have worked all my adult life in the design and support of advanced systems 
and I can assure you that nothing is more troublesome in the field than a 
software based design, which invariably also cost far more than the supposedly 
expensive hardware it replaced. I feel confident the actual cost to make the 
1pps software based divider, for example will be far in excess of the cost of a 
few 74HC390's.

I have no argument with computer based anything, it is merely critical to 
understand the staggering volatility of that platform, the true scope of costs, 
and the consequences of failure. I have watched many companies suffer under the 
burden of software development gone off the rails, and know how much in 
retrospect they wished for a different path.  and yes, this was written on a 
computer, I own 8 of them,
so please look for the real message here, don't go for the sarcastic response.

all the best,
walter

-- 
Walter Shawlee 2, President
Sphere Research Corporation
3394 Sunnyside Rd.,  West Kelowna,  BC
V1Z 2V4  CANADA  Phone: (250) 769-1834
walter2 at sphere.bc.ca
WS2: We're all in one boat, no matter how it looks to you.
Love is all you need. (John Lennon)
But, that doesn't mean other things don't come in handy. (WS2)