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24507Re: [midatlanticretro] IMSAI front panel ECO question

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  • Dan Roganti
    Feb 26, 2012
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      On Sun, Feb 26, 2012 at 4:57 PM, Richard Cini <rich.cini@...> wrote:

      All ---

      I'm working on a side project with some of the N8VEM guys and a question came up about interpreting the instructions with implementing ECO 77-0098 (a post-rev.4 change which prevented spurious triggering of the ONE-SHOTS during RUN mode, causing unpredictable program execution.). 

      I'm making the changes to a printed copy of the rev.4 schematic. Unless I read it wrong, it seems that the CLR line on U23 is not reconnected to anything after the steps are applied. Has anyone looked at these steps and/or applied them to a schematic and can confirm the steps are correct?

      That does look very strange. You  can't leave the CLR input hanging like that. That must be another 35yr old typo.
      My CPA board is also Rev.4 and the schematics are dated 2/27/76 and I see that ECO is from 9/1/77. So I'm not sure yet if it's been implemented on mine - I'd have to tear apart my front panel to check.But I haven't experienced any weird symptoms on mine for which this is supposed to alleviate.   I know I have the STOP mode implemented , ECO 77-0035 from 3/5/77.


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