Wednesday, May 11, 2016

DC600HC IOTAMAT Format Blank QIC Cartridge Analysis (HCD format)

Click here to download the .logicdata file that I display in my video above.

I see in the following doc, that there are a number of different "preformatted" QIC cartridges of this era:


Compatibility and Competitive
Cross Reference Information
Data Cartridge Tape Products 


Looks to be a 3M thing, since these are all their model tapes, and this is their publication.

And searching for all of the above, yields this:

Major Companies of Europe 1993/94: Volume 2 Major Companies of the United ...

OK, but looking deeper:

superscript-14 says  "Cartridges are formatted for use on systems which incorporate the 3M HCD-75 and HCD-134 drives."

HCD-75 Drive?  What is that?  Well, this looks like a good manual, especially the bottom of page 9:


Keys!  Fantastic, that's what those things are called.

Ah, a format!  IMFM:

ISO 8063-1:1986 

Information processing -- Data interchange on 6,30 mm (0.25 in) wide magnetic tape cartridge using IMFM recording at 252 ftpmm (6 400 ftpi) -- Part 1: Mechanical, physical and magnetic properties

So, that's the best definition of what I found on this BLANK tape, BUT, then it goes on to define the data block format.

Disclaimer:  This is the point at which I stop pursuing the knowledge of the IOTAMAT format purely for the sake of learning the format.  From here, I will start focusing on why it did, or did not, belong on the Point 4 IRIS system backups tapes that was written on my project's tapes (which is why I wanted to learn about this format in the first place)

But the data block format at the bottom of page 12 does NOT match at all what I found on my DC600HC tapes with the Point 4 IRIS system backed up on them.

And 16 tracks?  (Not even close...try 4! on my Point 4 IRIS system backup tapes)

So, did the Kennedy 64xx format (as I identify it) even NEED to use an IOTAMAT format tape, or did it just ignore those existing things, and write whatever it wanted anyway?

And the Kennedy 6450 device manual, which DID match the block format of what was written on those tapes, mentions nothing about needing DC600HC, IOTAMAT, or preforamtted tapes of any kind.  Actually, it defines cartridge tapes as "3M Type DC300A, 300XL, and DC600A".  Those don't have any preformat.

I'm starting to think it's the latter.  It would/should have worked the same with or without these formatted tapes.  But, hey, I'm still open.


The Computer History Museum has nice vintage one in their inventory, which appears identical in vintage and style to some of the cartridges that I have for the Point 4 IRIS.

I am noticing that this one is also wound to the "end", almost as if that is its starting point.


I found this somewhere, but I'm not quite sure where yet.  It seems relevant:

9144/9145 formats Traditional HP drives do not use the QIC format, but rather one invented by 3M some five years before QIC.  It is called HCD format. Cartridge Tape Specification Overview:  
 | Characteristic     | HCD Cartridge Tape      | QIC Cartridge Tape       |
 | Approx. Incep. date| 1980                    | 1985                     | 
 | Drive Hardware     | 9144A, 35401A, 9145A    | various                  | 
 | Mechanical form    | 3M DC150 and DC600      | 3M DC150 and DC600       | 
 |   factor           |                         |                          | 
 | Merchandising name | Cartridge tape, CTD     | QIC-24 or QIC-120        | 
 | Typical supplier   | HP (for HP customers)   | any discounter           | 
 | Generic designation| DC600HC, DC615HC,       | DC600A, DC615A           | 
 |                    |   DC600XTD, DC615XTD    |                          | 
 | Tape pre-format    | Full-track 3M HCD-75    | <none>                   | 
 |                    |   or modified HCD-134   |                          | 
 | Data format        | MFM                     | NRZI                     | 
 | EOT/BOT            | Delimited by pre-format | Optical tape sense holes | 
 | Rewind position    | Right spool empty.      | Left spool empty.        | 
 | Capacity           | 67 or 134 Mbytes        | 60 or 120 Mbytes         | 
 |                    | 16 or 32 Mbytes for     |                          | 
 |                    | short tapes             |                          | 
 | Number of tracks   | 16 or 32                | 9 or 15                  | 
 | Access types       | Random (re-writeable)   | Serial only              | 
 |                    |   or serial             |                          | 
 | Average seek (60M) | 2 minutes               | 20 minutes               | 
 |    "     "ek (15M) | 30 seconds              |  5 minutes               | 
 | Error control      | Read-while-write        | Read-while-write only    | 
 |                    |   plus ECC              |                          | 


See the discussion on this topic.


David Sutherland adds this as his contribution.  Thank you, David!

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