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Re: [midatlanticretro] Lobo floppy drives

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  • Richard Cini
    Bill -- I finished examining and cleaning the interior of the drive enclosure this evening. I took note of the jumpers on both drives ‹ interestingly there
    Message 1 of 40 , Nov 16, 2012
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      Bill --

      I finished examining and cleaning the interior of the drive enclosure this evening. I took note of the jumpers on both drives — interestingly there were many differences between the jumper settings, other than what would be expected (i.e., the drive select and the termination).

      Here are the jumper settings:

      Drive0: installed — DS1-T1-X-B-A-Z
      Drive1: installed — T2-HL-800-DS2-T3-T4-T5-T6-T1-X-B-A-Z (this drive is at the end of the cable)

      Drive1 also had a drive_ready modification which resulted in pin22 being put on pin4 of the interface connector (jumper R cut; wire from R to pin 4).

      Given this configuration I'm not entirely sure what system this might have been used in since the drives are set so differently. So, I reset the jumpers per the CompuPro Disk 1 instructions and once I build a cable, I can try it on my IMSAI. Overall the drives look very clean and free from excessive dust.
        
      Rich

      --
      Rich Cini
      Collector of Classic Computers
      Build Master and lead engineer, Altair32 Emulator


      From: B Degnan <billdeg@...>
      Reply-To: "midatlanticretro@yahoogroups.com" <midatlanticretro@yahoogroups.com>
      Date: Wednesday, November 14, 2012 9:46 AM
      To: "midatlanticretro@yahoogroups.com" <midatlanticretro@yahoogroups.com>
      Subject: Re: [midatlanticretro] Lobo floppy drives

       

      Sorry, I mean jumpers on the drives in the enclosure. Here is an
      example..

      http://vintagecomputer.net/intel/MDS-720/

      Bill

      -------- Original Message --------

      > From: "B. Degnan" <billdeg@...>
      > Sent: Wednesday, November 14, 2012 9:30 AM
      > To: midatlanticretro@yahoogroups.com
      > Subject: Re: [midatlanticretro] Lobo floppy drives
      >
      > It might be a pain, but if you have a chance to take a picture of the
      > jumpers on the board, I'd be interested to see what you have. I just did
      a
      > set of SA800's from an Intel MDS. I expect yours to be completely
      > different.
      > bd

    • Mike Loewen
      ... Here s the service manual for the Tandom TM-848, with the schematics in the back: http://bitsavers.trailing-edge.com/pdf/tandon/TM848_service_1982.pdf
      Message 40 of 40 , Dec 15, 2012
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        On Sat, 15 Dec 2012, joshbensadon wrote:

        > --- In midatlanticretro@yahoogroups.com, Mike Loewen <mloewen@...> wrote:
        >>
        >> The double-sided drives have a 2S signal on pin 10 of the interface
        >> connector to indicate single or double-sided media. The outputs of the
        >> respective pulse-shaping ciruitry for each sensor is essentially ORed to
        >> form a single Index pulse output.
        >
        >
        > Cool, so I can imagine the two sensor signals going to an RS flip flop
        > to provide the 2S signal and as you said to an OR gate for the index.

        Here's the service manual for the Tandom TM-848, with the schematics in
        the back:

        http://bitsavers.trailing-edge.com/pdf/tandon/TM848_service_1982.pdf

        Knock yourself out. :-)

        > Hmm, thinking about why, I guess the design was to create a hardware
        > error if a user placed a DS disk into a SS drive. As Rich found, the
        > lack of index pulses caused a drive not ready. Correct me if I'm wrong,
        > but in later 5.25" drives, they did not change the index sensor
        > location. Then I suppose the errors created would be software
        > generated?

        The 5.25" drives only had a single index hole aperture.

        > I vaguely remember hearing a discussion about how computers switched
        > from hardware solutions to software solutions, then back to hardware.
        > I just don't know the dates, could this 8" to 5.25" be part of that
        > switch?

        I couldn't say. Certainly Woz did a lot in software for his Apple II
        disk controller design. Another odd thing about the 8" drivers vs the
        5-1/4" drives was that the 8" drives had a write-enable notch, while the
        5-1/4: drives had a write-protect notch. Very confusing.


        Mike Loewen mloewen@...
        Old Technology http://sturgeon.css.psu.edu/~mloewen/Oldtech/
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