Diecrusher Posted October 4, 2015 Share Posted October 4, 2015 I am trying to finish up a restoration of my Model 4 GA. I've installed an additional 8 ram chips and have done the well known jumper wire mod from the bottom of capacitor C39 to pin 16 of U33 to add the additional 64k of ram. As you can see from the pictures, I am getting bad ROM values and most of the memory is missing. RAM installed is 128k so why is it showing as 48082? I have a non-gate-array machine I can swap chips from but it was purchased non-working so there is a risk there. I am going to research if I can swap ROMS from the NGA machine. Any help or suggestions would be appreciated as I am in the dark here! Thanks, Tim Quote Link to comment Share on other sites More sharing options...
Diecrusher Posted October 13, 2015 Author Share Posted October 13, 2015 (edited) Some info that I have gathered from others and through research that might help someone in the future with the same issues: The RAM size showing is correct as TRSDOS or BASIC (can't remember exactly which one) can't see any ram beyond that anyways. CP/M can use the extra as a RAM disk of sorts, so I am told. The non-matching CHECKSUM numbers are correct also as those values are the Model 4 ROMS being read in Model III mode. Edited October 13, 2015 by Diecrusher Quote Link to comment Share on other sites More sharing options...
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