PDP-11/20 vd one that just says pdp 11 what are the date differences?? OEM?

Fred Cisin cisin at xenosoft.com
Mon Feb 22 12:50:10 CST 2016

On Mon, 22 Feb 2016, Paul Birkel wrote:
> I wonder how long it took them to "figure it out"?  I seems that the
> family-plan dates to April 1969.

When everybody realized and accepted that there would be more than one 
sub-model, and decided that it might be handy to be able to tell them 
apart.  There may have been some holdouts in some departments, such as 
silk-screening the panels.

By analogy, the phrase "single density" didn't originally exist.
After "DOUBLE-density" was developed, THEN "single density" needed a name.
Although just sticking with "FM" and "MFM" would have been a lot better!
(Although I guess that it was inevitable that marketing would invent "HD", 
instead of "double data transfer rate MFM".)

There were even a few companies that freely intermingled HEADS V density!
Intertec/Superbrain decided to call their 5.25" 40 track DSDD, "QUAD 
density", because it was twice the capacity of the 40 track SSDD!  Then, 
when they added an 80 track DSDD, they caalled that "SUPER density", 
abbreviated "SD"!  So, if you encounter an alien disk labelled "SD", it 
might be 720K/800K, not 100K.

Similarly, if you were to search ancient archives, the phrase "World War 
TWO" was first used BEFORE there was any mention of "World War ONE".
It wan't until a second happened, or was expected, before anybody had any 
reason to declare the "Great war"/"World War" to be "nuber ONE".

So, the use of any sort of "first" name doesn't occur until "second" is 

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