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Thread: Kennedy 1400 R

  1. #1

    Default Kennedy 1400 R

    Hello all,

    I've seen some PDP machines in the past which had Kennedy drives.
    I can buy this Kennedy 1400 R drive for a decent price...

    Kennedy 1400 R.jpg

    But no cables, and no controller. Any use of picking it up? Or just forget about it
    being an endless project? I don't want too much useless old iron in my home...

    Regards, Roland
    WTB: Case for Altair 8800 ...... Rolands Github projects

  2. #2
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    I don't know about this model, but some Kennedy small-reel drives (like this one) were made for the key-to-tape data entry community and often use steppers (incremental positioning) for drive. Many lack any sort of read circuitry.

    So be careful.

  3. #3

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    Quote Originally Posted by Roland Huisman View Post
    I've seen some PDP machines in the past which had Kennedy drives.
    I can buy this Kennedy 1400 R drive for a decent price...

    But no cables, and no controller. Any use of picking it up? Or just forget about it
    being an endless project? I don't want too much useless old iron in my home...
    TL;DR - Run away screaming (especially from a seller who doesn't know how the tape is supposed to be threaded!)

    No relation, but some generic information from my somewhat error-prone, non-parity-equipped main memory:

    Most older OEM tape drives used either an "unformatted Pertec" or "formatted Pertec" interface. This leaves out special-market drives like IBM compatibles, of course. Unofrmatted Pertec just gave you the flux transitions as recovered from the tape, and you had to decode them. 800BPI and older formats were reasonably simple and easy to decode in software using 8080, 6502, etc. processors - you could probably do up to around 45 IPS with careful assembler code. 1600BPI was much tougher, since it was PE recording. I never saw an unassisted software PE implementation. Formatted Pertec did the decoding for you, but you still had to talk to the drive at a pretty low level. Unformatted Pertec used 3 connectors (maybe 36-pin? I don't remember) while formatted Pertec used 2 50-pin connectors.

    The actual Pertec formatter was quite a bit of kit - Cables of multiple thick black and white twisted pairs for each of the 3 unformatted drive connectors, and a card cage with 3 or 4 cards stuffed full of logic. This was made a bit harder to deal with by the fact that the Pertec interface standard was old enough that it was specified in DTL, not TTL. The genuine Pertec formatter had to be configured with jumpers and often component swaps to deal with a specific model and speed of tape drive. Trying to get an unformatted Pertec drive without its original formatter working is likely to be an exercise in frustration and only worth it when trying to maintain an exact configuration in a museum.

    "Modern" OEM 9-track drives like the Cipher F880 started out as formatted Pertec, but there was already so much microprocessor control going on that switching to a more modern interface became practical - and necessary, once drives like the Cipher became 6250BPI (GCR) capable - in fact, that's the reason for the F880's oddball 3200BPI PE - it was so it wouldn't confuse controllers.

    Once drives sprouted SCSI interfaces (and other manufacturer-specific ones like DEC's LESI and later STI) the older drives were surplussed out pretty quickly. A lot of those were "high mileage" drives even then.

    With a multitude of different mechanical parts, old tape drives can be a nightmare to work on. You will likely need to custom create items like rubber capstan rollers, etc. Some people think tension-arm tape drives are easier to work on than vacuum-column ones. I disagree - the potentiometers in the tension arms are scratchy (like the volume on an old radio) and the drive will likely become very confused. All of the custom adjustment fixtures, etc. are long gone.

    I would suggest that if the intent is to get a tape drive for actual use (as opposed to a display artifact), you stick with something from the SCSI era (ideally) or at least the formatted Pertec (with microprocessor-controlled drive) era, since they can usually tell you what they think is wrong.

  4. #4

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    Chuck and Terry,

    Thanks a lot for the warnings. On the drive was a big round connector with many pins on it.
    But since there is no cable and certainly no controller I decided to ask here first... I leave the
    drive there, it was 50 Euro (approx 50 Dollar) but I'm not a collector of useless old iron

    I've got an Anita MK8 calculator (really a bargain), three dectapes and a Data General Nova 3
    front panel from that museum. So that will be enough for now

    Regards, Roland
    WTB: Case for Altair 8800 ...... Rolands Github projects

  5. #5
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    By comparison, here's the manual for the Kennedy 1600 which was part of the same series. You can see what I'm talking about. I think Sellam may have one of these yet.

    Not having a formatter isn't as bad as it used to be. I use an HP 7970 with a 7/9 track head with no formatter; instead I use a STM32F407 MCU to wiggle the lines. Works very well, especially for old 7 track tapes. Modern microcontrollers are far more powerful than the old logic of 40 years ago. Heck, you could even dump everything but the read amplifiers; MCUs have great multichannel DSP capability.

    But not having read heads at all can put a cramp in your style.

    The gotcha is that it takes programming, of course.

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