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12530Re: My latest elf2k in a case project

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  • David Keith
    Feb 18, 2013
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      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




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