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Re: [midatlanticretro] Lobo floppy drives

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  • B. Degnan
    I m hoping it s a trs 80 or maybe an actual LOBO computer. ... ... unit. ... ... also ...
    Message 1 of 40 , Nov 17, 2012
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      I'm hoping it's a trs 80 or maybe an actual LOBO computer.

      -------- Original Message --------
      > From: "Richard Cini" <rich.cini@...>
      > Sent: Saturday, November 17, 2012 8:35 AM
      > To: "midatlanticretro@yahoogroups.com"
      <midatlanticretro@yahoogroups.com>
      > Subject: Re: [midatlanticretro] Lobo floppy drives
      >
      > Bill --
      >
      > I emailed the original seller to see if he knows the history of the
      unit.
      > When I hear back I'll let you know.
      >
      > Rich
      >
      > --
      > Rich Cini
      > Collector of Classic Computers
      > Build Master and lead engineer, Altair32 Emulator
      > http://www.classiccmp.org/cini
      > http://www.classiccmp.org/altair32
      >
      >
      > From: B Degnan <billdeg@...>
      > Reply-To: "midatlanticretro@yahoogroups.com"
      > <midatlanticretro@yahoogroups.com>
      > Date: Friday, November 16, 2012 11:47 PM
      > To: "midatlanticretro@yahoogroups.com"
      <midatlanticretro@yahoogroups.com>
      > Subject: Re: [midatlanticretro] Lobo floppy drives
      >
      >
      >
      >
      >
      >
      > Interesting....the S800's in the Intel MDS 720 photoed on my web site
      also
      > have significantly different jumpers drive 0 vs. drive 1. Maybe that's
      how
      > it's done, or the boot drive has a lot of differences that the non boot
      > drive. I wonder what this drive was used for.
      > bd
      >
      > -------- Original Message --------
      > > From: "Richard Cini" <rich.cini@...
      <mailto:rich.cini%40verizon.net> >
      > > Sent: Friday, November 16, 2012 11:19 PM
      > > To: "midatlanticretro@yahoogroups.com
      > <mailto:midatlanticretro%40yahoogroups.com> "
      <midatlanticretro@yahoogroups.com
      > <mailto:midatlanticretro%40yahoogroups.com> >
      > > Subject: Re: [midatlanticretro] Lobo floppy drives
      > >
      > > 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
      > > http://www.classiccmp.org/cini
      > > http://www.classiccmp.org/altair32
      > >
    • 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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