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Unique S-100 computer (Z-80/Vector Graphic/Micropolis)

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    Originally posted by deramp5113 View Post
    You can pick out the pattern even with an incandescent bulb. Not as obvious as fluorescent, but it’s there.

    Mike
    True enough, but incandescents are getting as hard to find as 'real' fluorescents and certainly not nearly as clear. But if that's all you've got...

    BTW, Mike, let me take this opportunity to thank you for your many contributions to the hobby!

    m

    Comment


      LOL I did do this with a real fluorescent fixture - I had one for plants/seed starting - not CFL or LED. I swear I can't make out any pattern at all.

      Comment


        We can rough check timing with a scope. Measure sector to sector time by monitoring test point 3, negative edge triggered. Note you’ll have a half-sector time slip in periodically at the index pulse. What interval do you measure?

        Comment


          Originally posted by nullvalue View Post
          LOL I did do this with a real fluorescent fixture - I had one for plants/seed starting - not CFL or LED. I swear I can't make out any pattern at all.
          Well, there is the possibility that the speed is too far off; time to check it the hard way as Mike suggests

          Comment


            Originally posted by deramp5113 View Post
            We can rough check timing with a scope. Measure sector to sector time by monitoring test point 3, negative edge triggered. Note you’ll have a half-sector time slip in periodically at the index pulse. What interval do you measure?
            I'm not sure I have my scope set up to capture this correctly, maybe you can make sense of this? I've recorded what TP3 looks like during the boot loop. Volts/Div is set to 1V, Time/Div is 2ms.

            https://www.youtube.com/watch?v=Q72uuYmHDow
            Last edited by nullvalue; May 31, 2020, 04:01 PM.

            Comment


              The flicker is the full rotation index pulse at 1/2 the sector time that you have to ignore. Looks to me like that drive is about 5.2 divisions or 10.4ms. That’s way too quick, nominal is 12.5ms (300 rpm, 16 sectors). See if you can adjust R89 enough to get the drive to 12.5ms (6.25 divisions). Then you should be able to see the strobe pattern and do final adjustments.

              Mike

              Comment


                Thank you, that helped me get it dialed in! I couldn't see a pattern at all, frustrated I tried under my normal LED bulb lighting and behold, a spinning pattern! I adjusted until the pattern holds steady, as can be seen in this video:

                The outer pattern holds still (that's what we wanted, right?)
                https://www.youtube.com/watch?v=kt9ZcF1eL2U

                However, I went through the whole disk creation process now - twice - and same results as before. Disk writes successfully, but then (B)oot just sits there spinning the disk. It finds track 0 but then just spins.

                Comment


                  See what the boot ROM checksum is. Type "Q F800 F8FF"

                  Mike

                  Comment


                    Yep already tried that.. it's "BC"

                    Comment


                      Well damn, yep, that’s correct. Post pictures of the Micropolis controller board mods. If the motor mod is done (that one stops the motor about four seconds after the drive is deselected), but the “ready mod” is not done, CP/M disks don’t work. Did you ever try the “ CPM22A-MikeD.VGI” disk images instead?

                      Mike

                      Comment


                        I will try the other disk images. In the meantime, here are some closeups of the controller board - can you tell which mods have been done?

                        20200601_211452.jpg 20200601_211504.jpg 20200601_211525.jpg

                        20200601_211535.jpg 20200601_211541.jpg 20200601_211546.jpg

                        Comment


                          Interesting; are these FDC mods documented somewhere?

                          TIA

                          Comment


                            Originally posted by MikeS View Post
                            Interesting; are these FDC mods documented somewhere?
                            The mods are documented toward the end of the floppy controller manual here: https://deramp.com/downloads/vector_...Controller.pdf

                            Mike

                            Comment


                              Originally posted by nullvalue View Post
                              here are some closeups of the controller board - can you tell which mods have been done?
                              It looks like the motor on/off mod and the ready mod are both implemented, so that's not the problem. Let me know what happens when you try the other disk images.

                              Mike

                              Comment


                                Originally posted by deramp5113 View Post
                                The mods are documented toward the end of the floppy controller manual here: https://deramp.com/downloads/vector_...Controller.pdf

                                Mike
                                Thanks again, Mike!

                                Comment

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