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

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    Good tip - I'll check that out. However, the cap was on the Bit Streamer board. The system is not booting even without the Bit Streamer installed. Since I do have some (uninitialized) video, wouldn't that point to a problem being on the 12K PROM/RAM or Z80 CPU?
    Last edited by nullvalue; April 30, 2020, 08:11 AM.

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      Traced what I hooked up to. The negative end runs to the VEE pin of a 1488P chip. It's carrying -12v.

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        Originally posted by nullvalue View Post
        Good tip - I'll check that out. However, the cap was on the Bit Streamer board. The system is not booting even without the Bit Streamer installed. Since I do have some (uninitialized) video, wouldn't that point to a problem being on the 12K PROM/RAM or Z80 CPU?
        It really doesn't matter on what board you cause a power supply short if that short, in turn, damages the system power supply. Though with a 7912 in between the short and the system -16v supply, it would not be typical to get past the regulator in a catastrophic way. The short may have damaged the negative supply on another board.

        Measure the system supplies (-16v, +16v, +8v) and see where they are. If they look fine, then look on the boards and check the voltage of any onboard negative supplies and see if they're correct.

        Mike

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          Originally posted by deramp5113 View Post
          Measure the system supplies (-16v, +16v, +8v) and see where they are. If they look fine, then look on the boards and check the voltage of any onboard negative supplies and see if they're correct.
          I checked the rail voltage and it does not appear that I have a stable -16v on pin 52. I'll check it one moment and it's fine (like -18v) and the next it's gone. Guess I'm going to have to replace the power supply or at least part of it? What's the current best approach for doing this?

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            I was testing voltages with load vs no load. Pulled everything out.. put it all back in and what do you know, system is booting fine now and my -16v rail is back.. bizarre. Will get back to serial testing... lesson learned: don't assume negative end of caps are ground!

            Edit: I think I found my problem with the power supply - may have been nothing to do with my scope hookup afterall. I think my molex connector supplying power to the backplane is lose. I accidentally wiggled it while working in there and the same thing happened where the screen scrambled. This is a relief, I love simple explanations.

            BTW for the serial communications: I did try bumping it up to 9600 baud. Still able to transmit data to the terminal PC, but nothing on the receiving end. (I 06: 00) - will start tracing the signal across the board.
            Last edited by nullvalue; May 1, 2020, 06:16 AM.

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              You can quickly check that the input path from the 8251 to the processor is OK by doing an IN 07. Does that give something besides 00?

              Mike

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                Yes it returns "05".

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                  So after some further testing, I am able to see the data reach the 1489 receiver chip input (pin 10, Input C) but nothing coming out and nothing reaching the 8251. I'm going to order a replacement for the 1489 and cross my fingers.

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                    Originally posted by deramp5113 View Post
                    You can quickly check that the input path from the 8251 to the processor is OK by doing an IN 07. Does that give something besides 00?
                    20200509_195530.jpg

                    Another problem solved! After replacing the 1489, I am now able to both send and receive data. So.. you had mentioned something about being able to manually send initialization codes?

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                      You won’t need to send init codes. The fact that the manual in/out tests work prove that the PROM monitor initialized the port. I’ll update PC2FLOP to allow use of port 6/7 for transfer and then you can try creating a disk. I’ll let you know when it’s posted.

                      Mike

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                        You wonít need to send init codes. The fact that the manual in/out tests work prove that the PROM monitor initialized the port. Iíll update PC2FLOP to allow use of port 6/7 for transfer and then you can try creating a disk. Iíll let you know when itís posted.

                        Mike

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                          I've uploaded a new version of PC2FLOP that supports the port at I/O address 6/7 here: https://deramp.com/downloads/vector_...%20controller/

                          Repeat the procedure you performed previously to load PC2FLOP.COM into your machine. Enter the bytes shown in LOADER.PRN starting at address zero using the monitor's "P"rogram command. You'll need to change I/O port address references from 4/5 to 6/7 (i.e., change 04 to 06, change 05 to 07).

                          Mike

                          Comment


                            Originally posted by deramp5113 View Post
                            I've uploaded a new version of PC2FLOP that supports the port at I/O address 6/7 here: https://deramp.com/downloads/vector_...%20controller/

                            Repeat the procedure you performed previously to load PC2FLOP.COM into your machine. Enter the bytes shown in LOADER.PRN starting at address zero using the monitor's "P"rogram command. You'll need to change I/O port address references from 4/5 to 6/7 (i.e., change 04 to 06, change 05 to 07).

                            Mike
                            Not sure if I've done something wrong or not.. After entering LOADER.PRN, I type G 0000 - nothing happens on the screen. In Teraterm I begin the transfer - about 75% of the way through sending the screen on the S100 goes to all block characters. After transfer, I do a reset, and a D 0100. It's filling with character '87' through about 0134, then seems like the rest of memory is filled with '97'.

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                              Ah it appears I modified the LOADER.PRN incorrectly. It seems it is working correctly but I think I'm having a problem with my USB to Serial adapter, partway through sending the file the LED's stop blinking and basically hangs the PC. Going to try adjusting the baud rate etc.

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                                Ok so I have managed to transfer the program, 9600 and 4800 baud both seem to be working very well. - I haven't reviewed the transfer byte for byte but it appears correct because I am to see the strings from the program as part of the memory dump. However when I attempt to run (G 0100) I just get this dump.

                                20200511_103033.jpg
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