Loading ...
Sorry, an error occurred while loading the content.

Re: [cosmacelf] Re: My latest elf2k in a case project

Expand Messages
  • Lee Hart
    ... That would be interesting! Perhaps the easiest way is to take a good photograph of the front panel, and make a color print of it. Cut holes for the various
    Message 1 of 51 , Jan 1, 2013
    • 0 Attachment
      On 12/31/2012 9:21 PM, David Keith wrote:
      > I have been wanting to build a working mocked up version of an IBM 370/148
      > Mainframe front panel to hang in my office wall, but lack the artistic
      > skills

      That would be interesting! Perhaps the easiest way is to take a good
      photograph of the front panel, and make a color print of it. Cut holes
      for the various lights and switches, and install them.

      > Lee Hart's reference to his EV web site, blew me away...

      Thanks! It's a *big* project, and we've been at it for about 5 years now.

      > I was researching how to build an EV bicycle. The bike trail I use to ride, aligned with some high voltage
      > power lines, and I was trying to figure out how to use my bike frame
      > (with a coil of wire) to tape off enough power to drive my 10 speed. LOL
      > Thank God I didn't do it, it would have been a very shocking experience

      I don't think there's a chance of getting a shock from it. The main
      problem is that the power lines are normally well balanced, to minimize
      radiated power. Thus there is little or none to be picked up.

      The power companies always strive to run equal and opposite currents in
      the wires. The radiated fields from them cancel out once you are more
      than a few times the spacing between the wires away from them. It's
      called "transmission line theory" if you want to study up on it.

      But once in a blue moon, they'll screw up. If the currents are *not*
      equal and opposite, you *can* make an air-core transformer with your own
      wires at ground level. The efficiency is poor (due to the air core at
      60hz), but who cares if they loose 100 watts for every watt you receive. :-)

      In one famous case, a power company installed a set of high power lines
      over a farm. The farmer kept complaining that he was getting shocks, the
      lights in his barn would light even with the switch off, etc. The power
      company refused to take him seriously. So he strung up a big loop of
      wire under the power lines, and used the power received to run everything.

      Now, the power companies have meters to measure how much power is going
      out on a line, and how much is being received at the other end. It's
      intended to detect damaged insulators, loose connections, trees on the
      wires, etc. His power draw drove them nuts, because they couldn't find
      the source of the leakage! They eventually figured it out, re-balanced
      the lines, and the power loss went away.

      > But seriously guys, why don't we channel all this creative energy into a
      > new product the group can sell as a kit or as assembled. Guys think
      > outside of the box (case )

      I think many of us design and build things for fun; not for profit. I
      know I do. There really isn't a market for most of these things. People
      want *cheap*, not clever -- and no hand-made low-production item can
      compete with the cheap flashy stuff from China, India, Mexico, etc.

      Take my Membership Card, for example. It costs $79, because sales volume
      is so low (I sell about 1 a week). But you can buy an Arduino for $29,
      because they sell a *thousand* a week. With that kind of sales volume,
      they can build them in China to get the price down, hire a staff of
      people to do development and sales promotions, etc. They have so many
      customers that there is a lot of "buzz" on the web to use it, further
      promoting sales. (Look at the Hack-a-day website, where it seems like
      every other project uses an Arduino).

      It's HARD to think of things that people will actually BUY for more than
      it costs you to make it. So you do it for fun; not profit.
      --
      Don't worry about people stealing your ideas. If your ideas are any
      good, you'll have to ram them down people's throats. -- Howard Aiken

      --
      Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
    • David Keith
      Thanks Craig, I see you are right.  I keep on forgetting that the System 370 ISA is/was not a physical architecture, but one that was emulated in the
      Message 51 of 51 , Feb 18, 2013
      • 0 Attachment
        Thanks Craig,
        I see you are right.  I keep on forgetting that the System 370 ISA is/was not a physical architecture, but one that was emulated in the mircocode/programming of the underlying model hardware.  Looks like 370/138 model was actually a 16 bit word, with only a maximum addressable memory of 1 mega bytes.
        Good Catch
        Dave


        From: cstull <cstull@...>
        To: David Keith <beloved_wind@...>
        Sent: Monday, February 18, 2013 3:03 PM
        Subject: Re: My latest elf2k in a case project
        Hi Dave,
        I think you are mistaken on the 370/138 control panel.  If you go to images.google.com and type in IBM 370/138 you will see that the item that was on ebay is identical to the 138 panel.  The 3705 panel doesn't look at all like it.
        The 138 must have been a shorter address machine because with five hex knobs to address memory, that would mean that the maximum addressable memory (FFFFF) would have been 1 meg.
        Lots of iron for a 1 meg machine.

        Craig

        --- In cosmacelf@yahoogroups.com, David Keith <beloved_wind@...> wrote:
        >
        > Thanks Bill, glad to see some old time mainframe system 370 programmers still out there.  I am aware of the Hercules 370 emulator, but never have/had the time to download it and play with it.
        >
        > Found this link for a IBM System 370 control panel for sell out on eBay, BUT it looks like someone took a IBM 3705 Communications Controller and fit it to be a 370/138 console.  NOT enough lights (16 bits + 2 parity) when there should be 32 bits + 4 parity, also not enough rotary selection switches at the bottom.  Very good conversation piece, LOL
        >
        > http://www.ebay.com/itm/321051214549?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
        >
        > Thanks
        > Dave




      Your message has been successfully submitted and would be delivered to recipients shortly.