On the Emulation of TU58s

Chuck Guzis cclist at sydex.com
Tue Jun 16 15:05:19 CDT 2015

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?


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