Destructive Imaging of DECTAPE II Media

[Mike Stein]

----- Original Message ----- 
From: "Brent Hilpert" <hilpert at cs.ubc.ca>
To: "General Discussion: On-Topic and Off-Topic Posts" 
<cctalk at classiccmp.org>
Sent: Tuesday, January 27, 2015 10:04 PM
Subject: Re: Destructive Imaging of DECTAPE II Media



On 2015-Jan-27, at 6:51 PM, Mike Stein wrote:

>
> ----- Original Message ----- From: "Brent Hilpert" <hilpert at cs.ubc.ca>
> To: "General Discussion: On-Topic and Off-Topic Posts" 
> <cctalk at classiccmp.org>
> Sent: Tuesday, January 27, 2015 7:32 PM
> Subject: Re: Destructive Imaging of DECTAPE II Media
>
>
> On 2015-Jan-27, at 3:58 PM, Mike Stein wrote:
>
>> I can't find it at the moment but somewhere I have a Burroughs digital 
>> cassette drive, capstan-less and capable of high-speed bidirectional 
>> seek. AFAIK it uses the standard half-track mono tape format, one track 
>> for data and the other for the clock.
>
> That description fits the tape system used in the HP9830. The tape 
> transport is actually a "DigiDeck" OEM'd by International Computer 
> Products,  out of Dallas, Texas. The head is non-standard though, in that 
> it R/Ws both half-tracks simultaneously.
>
>
>> Don't know if it'd be useful and not sure if I want to part with it 
>> permanently, but keep it in mind if nothing else works out and you get 
>> desperate ;-)
>
> I don't think it would be of any benefit to the OP's interest over what he 
> already has to work with.=
>
> ----- Reply -----
>
> Probably not, but I thought I'd mention it just in case; it doesn't use a 
> pinch roller though, and it is completely digital, FWIW.
>
> I don't recall whether it was a DigiDeck, but ISTR that I compared the BBM 
> unit to another digital deck that was (relatively) popular way back when, 
> and I'm pretty sure that they were different.
>
> http://www.picklesnet.com/burroughs/images/fullsize/burr0050.jpg
>
> They were mostly used with Burroughs Series L machines, but I think some 
> of the small B series could also be equipped with them. I've still got a 
> few boxes of utility, game and program tapes for Burroughs L series 
> machine, but working L's are pretty thin on the ground so I sometimes toy 
> with building an emulator; that's why I still have the tapes and the 
> drives (although unfortunately I threw out a lot of paper tapes a long 
> time ago), but that project is pretty far down on the list...

Can't tell from that pic - can't see internals.

Pics of the 9830 transport well down the page here:
http://www.cs.ubc.ca/~hilpert/e/HP9830/gallery/index.html

Some tech details of use in the 9830:
http://www.cs.ubc.ca/~hilpert/e/HP9830/hardware.html#tape

although I should correct my earlier statement: the HP uses 2 half-tracks 
for 1 bits and 0 bits, not data and clock as you indicate for the Burroughs, 
but they're still very similar, the diff would just be in the electronics.

----- Reply -----

No, completely different mechanically and electronically, and the analog and 
most of the digital electronics are on a  set of five cards at the back of 
the unit.

But that doesn't mean they couldn't read each other's tapes with some effort 
and a few jumper wires ;-)

Found the Tech manuals; FWIW:

Model: A9490
Read speed:
 Start & stop: 10 ips
 Continuous: 30 ips
Write speed: 10 ips
Mode:
 NRZ (2 tracks, clock & data)
  or (optional):
 PE (Single track, can use both sides)
Rewind speed: 60 ips

Doesn't Al have one of these at the CHM on a B700 or something similar?