On 06/16/2015 11:30 AM, Henk Gooijen wrote:
well, the tiny space between the tape and the air bearing could
be regarded a vacuum column, but it's a very short one :-)
The two air bearings are immediately above and below the R/W
and erase head. And they do *not* rotate. The tape glides on
an air cushion over the bearing.
Yeah, a case of mental dyspepsia.
So do any post-1980s 1/2" open-reel tape drives employ vacuum columns?
I was thinking of DG drive (about half-rack size) that I believe had
them, but I"m not sure of the date of manufacture.
Does this apparent lack of start-stop on a dime drives have anything to
do with the decline in tape as a working medium (as opposed to a backup
or distribution medium)? This is obvious when one looks at an OS such
as UNIX or PRIMOS; the tape was treated as pretty much an archival device.
Used to be that either Flores or (later) Knuth on sort/merge operations
was a standard on many a programmer's bookshelf. Not so much, I
gather, in the last couple of decades?
--Chuck
