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34784Re: [midatlanticretro] S100 Floppy Controller

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  • Paul Birkel
    Mar 18, 2014
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      Which is why I wondered about the IBM brow-ness :->.  Surely using a UART was a step "up" from discrete TTL (if that's what was the original IBM S/370-era implementation)!


      On Tue, Mar 18, 2014 at 7:42 AM, <bob@...> wrote:
       

      And the UART was far more advanced than an Apple disk controller; all the serialization and track stepper control was done in software!

      Bear in mind how expensive an FDC was back then compared to other chips.  It was probably hard for engineers to justify using such expensive devices.  If the floppy controller board cost $200 to make but needed only 500 hours of software work, versus $40 in parts and 2000 hours of software, usually the latter won.  Been there, done that with having LEDs rejected from a design because of the cost of the two resistors and two LEDs!

      Bob


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