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Re: [cosmacelf] Notes on MSI/88e Deconstruction

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  • J.C. Wren
    Why not just solder the chip to a machine tool pin socket, and insert that into another socket? (You *are* using machine tool pin sockets, right? Anything
    Message 1 of 3 , Jun 5, 2003
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      Why not just solder the chip to a machine tool pin socket, and insert that
      into another socket? (You *are* using machine tool pin sockets, right?
      Anything else would be sub-standard!)

      --John

      On Thursday 05 June 2003 17:10 pm, Mark Graybill wrote:
      > Well, I pulled the ROM out of the MSI/88e today and wasn't able to read it
      > with any of the 8Kx8 formats my ROM burner will read. The address and data
      > lines look like a standard layout, but I haven't traced the select logic
      > on the board yet to see what's going on. It's pretty easy to follow,
      > though, since it's on the same board as the CPU and right next to it.
      >
      > The chip appears to be a Signetics 27884, which I don't have data for. But
      > since the address and data lines looked standard, I thought I'd drop it in
      > the reader and give it a try. If anyone's got a suggestion for reading
      > this chip, let me know. If I can figure out the select logic I may put
      > together an adapter to allow the reader to treat it as a 2764.
      >
      > In the meanwhile, I'm going to check out the 1802 I pulled as well. If
      > time permits around my other projects, I'll try to do a quick free-run test
      > with it this afternoon.
      >
      > A note to people thinking about using the MSI/88e for parts--the
      > assemblers were very good about trimming the leads on the chips, so the
      > leads are too short for many types of sockets and for breadboards. Low
      > profile sockets will hold onto them pretty well, but you may want to
      > include something to hold the chip down to keep it from lifting out, even
      > then. If you're doing wire wrap you'd probably have to put the chip in a
      > low-profile socket then put that socket in a wire wrap socket, and have
      > something to hold the chip down since if the socket flexes or gets jarred
      > sharply the chip can fall out.
      >
      > Of course, if you're confident enough to solder the chip straight into the
      > circuit, this won't be a problem. Presently I'm not that confident. (Now
      > where did I put that lead stretcher?)
      >
      > -Mark G.
      >
      >
      >
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    • erd_6502
      ... For some parts, that s not cost-effective. Fortunately for me, I picked up a few tubes of 14-pin machine-pin sockets at the Dayton Hamvention last month
      Message 2 of 3 , Jun 6, 2003
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        --- In cosmacelf@yahoogroups.com, "J.C. Wren" <jcwren@j...> wrote:
        > Why not just solder the chip to a machine tool pin socket, and
        > insert that into another socket?

        For some parts, that's not cost-effective. Fortunately for me, I
        picked up a few tubes of 14-pin machine-pin sockets at the Dayton
        Hamvention last month for $1/tube (that's $0.04/socket)... I
        probably should have bought the entire bin! Normally, they are
        several times more expensive than that. New CMOS parts are
        frequently cheaper, CPUs, RAM and odd I/O chips notwithstanding.

        > (You *are* using machine tool pin sockets, right?
        > Anything else would be sub-standard!)

        Absolutely. Somewhere in the attic, I have a couple of cubic
        feet of machine-pin WW sockets. All I need is a good source
        of WW wire and I'm all set.

        -ethan
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