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Re: [midatlanticretro] Re: 128K Mac restored for MARCH

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  • B. Degnan
    ... For the 128K and 512k MAC s - It s just a AA battery on the outside of the chassis. I have both types of MAC. It could have just been a coincidence, but
    Message 1 of 8 , Oct 2, 2007
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      At 11:03 AM 10/2/2007 +0000, you wrote:
      >The battery provides power for the real-time clock and CMOS settings
      >circuitry. I don't believe the original, recommended battery is
      >available anymore, but one can be made up from a few double A's.
      >
      >I contributed an old working MAC which included a hard drive and
      >floppys. It's probably still in the basement.
      >
      >Ron


      For the 128K and 512k MAC's - It's just a AA battery on the outside of the
      chassis. I have both types of MAC. It could have just been a coincidence,
      but replacing the battery allowed me to get the disk to eject for the first
      time. The AA battery is installed like any toy with batteries...there's a
      little plastic flap/cover you pop off on the outside of the case. I am
      sure that there is a web resource that explains the battery, I did not look
      very hard. I will be demoing the Mac in class later in the semester and I
      will by then do more research.

      Bill
    • Herb Johnson
      ... I don t know what museum piece means specifically, but I appreciate the general sense that it s an early Mac 128K and so has some value in history. But
      Message 2 of 8 , Oct 2, 2007
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        "John Allain" <allain@...> wrote:
        >
        > Sounds like the Mac "model 1". If so then it's quite a
        > museum piece.

        I don't know what "museum piece" means specifically, but I appreciate
        the general sense that it's an early Mac 128K and so has some value in
        history. But there were many of them made, so they are not rare.
        Cosmetic condition determines the value of them, as they easily fade
        in roomlight or sunlight; working condition is of importance. The unit
        we have is slightly faded, probably worth "about" $200, could be
        bought for less. I would not be comfortable about an extended
        discussion of "value" beyond that.

        > If there's any interest in a slightly
        > later model for heavy display use I could pony up one
        > of those but have no model 1. Thanks for the donation.

        That's up to Evan, but MARCH has a few Mac Classics which would likely
        be adequate for use. I'm told there may be other "compact" Macs in the
        accumulation. Regarding "the donation", the Macs I worked on
        were already in MARCH's possession. I added some parts and time and
        knowledge, so I'll take some thanks for doing some work.

        > > if a member has a 400K floppy drive which
        > > is not working and wishes to donate it,
        >
        > How long did the 400K drive last? Maybe one of my later
        > models has one for yours.
        >
        > John A.

        The 400K Apple drive was only used in 128K and 512K Macs. The 512KE
        Mac used a 800K drive and updates to the ROMS and a controller chip
        called the IWM chip was also updated. There was an external 400K
        floppy drive, also.

        Thanks for the comments!

        Herb JOhnson

        Herbert R. Johnson, New Jersey USA
        http://www.retrotechnology.com/herbs_stuff/ web site
        http://www.retrotechnology.net/herbs_stuff/ domain mirror
        my email address: hjohnson AAT retrotechnology DOTT com
        if no reply, try in a few days: herbjohnson ATT comcast DOTT net
        "Herb's Stuff": old Mac, SGI, 8-inch floppy drives
        S-100 IMSAI Altair computers, docs, by "Dr. S-100"
      • Herb Johnson
        ... The PRAM memory requires a battery to retain its contents. Some non essential settings are there. In addition, the battery runs the time of day clock.
        Message 3 of 8 , Oct 2, 2007
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          "B Degnan" <billdeg@...> wrote:
          >

          > What is the battery for?


          The "PRAM" memory requires a battery to retain its contents. Some non
          essential settings are there. In addition, the battery runs the time
          of day clock. Running a small circuit all the time for years, on
          exposed copper circuits, in a humid environment, turns the copper to
          copper oxide - like your car battery's terminals. The battery will
          die, then crack open, and spill goop and spoil circuits. The battery
          contacts will corrode and fall off.

          In other words, batteries are evil.

          Herb Johnson
          usual Web page links, etc.
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