DECtape reliability?

Paul Koning paulkoning at
Thu Nov 12 09:48:13 CST 2015

> On Nov 12, 2015, at 8:47 AM, Johnny Billquist <bqt at> wrote:
> On 2015-11-12 14:24, Tom Moss wrote:
>> I've had very mixed (about 50/50) success with 9-track, but after reading a
>> bit about DECtape it looks like they should still be holding up nicely.
>> Anyone care to share their experiences?
> Not sure what there is to share. I've yet to encounter a DECtape I couldn't read.

You're right, DECtape is extremely reliable.  That makes sense: the tape is a sandwich, with the oxide underneath a mylar cover.  

My boss in college (a former and subsequent DEC OS developer) told me the same thing you did, that he'd never seen a DECtape fail.  Not even the one that was accidentally laundered (in some pants pockets), or the one that came loose from the hub and rolled all over the sawdust covered floor of the DEC mill building.

But I told him that I had seen some fail, and he saw it too.  This was in college.  We had an early RSTS system where DECtapes were used as public storage (to supplement the RK05 system disk).  Those were so busy that they did eventually wear out.  Sometimes they could be reformatted to bring them back to life, sometimes not.

And yes, between the redundant tracks and the physical construction of the tape, you should expect DECtapes to be perfectly readable even today.


More information about the cctalk mailing list