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I can't make John's serial board with His Z-80 Board

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    I can't make John's serial board with His Z-80 Board

    Hi All;

    I have John Monahan's S-100 Z80 CPU Board Ver 02, and I am trying to make John's Serial IO Board Version 3 work together..

    It will not Display anything on Tera-term, but Pressing any key on Tera-term makes it thru to the SCC IC..

    But, if I take out the SCC IC and connect pins 13 and 15 together, I shows the correct letter that I pressed..

    I have a Breakout Box, and I have been using that to see which signals are making it in and out..

    I have also tried different combinations for the other pins (DTR, DCD, CTS and RTS)..

    But, still nothing is displayed on the Screen..

    I do not have the USB Upload/Download connected, Do I need that to make the SCC IC work, or does the Z-80 Board and it's EPROM Load the SCC IC ??

    I am at a Loss, can anyone help me, find the Problem.. Thank You!!

    THANK YOU Marty

    #2
    Marty the Z80 monitor initializes the SCC. It will set it to a specified baud rate, stop bits, parity depending on how the code in the monitor is configured. Look for INIT_SCC_A: or INIT_SCC_B:
    You may not have these correct.
    This web page has fairly detailed build instructions. At what point do you get stuck

    http://s100computers.com/My%20System...IO%20Board.htm


    John

    Comment


      #3
      Hi John;

      Thank You for Your Prompt reply..
      A couple more things, that I forgot to type in the above entry.. I do not have CPM, as that is why I am trying to make it work, so I can get CPM working..
      That said, I did my first tests, using my Altair 8800 (8080) CPU, and putting into Ram the various test that would be needed for the Preliminary testing of the Serial Board..
      And, Yes, I already have tried and used the Serial Board Page, as a guide to what I am doing.. But, Thank You for the Link..
      So, I can see what the bits are doing, I have used 110 Baud, with everything else staying the same..
      I can see that from what You have written, that I need to look at Your Printed Listing for the Code for the Z-80, to see how you have the Baud settings set..
      When I do a Reset and a Run, I now get, (It took me awhile to find the correct wiring combination for P60 and P62, using an ohm meter and writing things down) the Leds to come on for the various signals, except for the indication of reading or writing to the Board.. That has never worked..
      So, has my Problem, been that I need to change from 110 Baud to what the Z-80 Board is sending to the SCC on the Serial Board, I think I at first tried the obvious baud rates of 9600, etc., but they didn't work, and so I went to 110 baud to see what was happening..
      So what settings did the Z-80 Board send to the SCC on the Serial Board, if I have not altered anything of the origional Z-80 code ??
      I have found my Eprom Programmer, (which took awhile) but, so far I have not been able to make it work any more, It needs a working XP system, and I have not completely pursued that any further, but, I may need to see what I have in my Eproms and see if I need to make any changes to it's contents..

      THANK YOU Marty

      Comment


        #4
        Hey Marty. How are you keeping in these funny times?

        The SCC is purely software programmable so (unlike the 6402 UART) it depends what the darn software does with it...

        What firmware EPROM code have you actually got in the Z80 card?

        Looking quickly at the MASTER V4.7 listings (and John should be able to confirm or deny this), the SCC appears to be initialised (by the table at SCCINIT as 19,600 bps 8 data (I will have to work out the parity and stop bit configuration as it is not mentioned in the comments).

        The use of the SCC appears to be dependent upon the setting of the sense switches on I/O port 0EFh (IOBYTE) - so how have you got these set?

        Dave

        Comment


          #5
          Hi All;

          A couple more things, I have Version 4.7 on the Eprom code for the Z-80..
          Also, John, what is the difference between Your Serial Board Version 2 which You show in Your Serial Board Instructions and ver 3 which is the Board that I have ??
          I am going to now Look at Your Z-80 code if I can find a listing for Version 4.7 and not Your latest 5.4 listing..

          THANK YOU Marty

          Comment


            #6
            http://s100computers.com/Software%20...R%20(V4.7).pdf (since I had it open).

            Dave

            Comment


              #7
              Hi all;

              Thank You for Your reply Dave, I haven't heard from You in Quite some time..

              I am doing fine for now, I hope You and Everyone is OK and doing fine as well..

              I will try it at 19,600 bps 8 data bits and see what happens..

              The use of the SCC appears to be dependent upon the setting of the sense switches on I/O port 0EFh (IOBYTE) - so how have you got these set?

              I don't know, I have not set any switches, except for F000, when I first reset and run..

              I have now tried it with all of the Sense switches at '0000, and then did a Reset and Run, but it makes no difference..

              I have also tried it at what You (Dave) suggested for Teraterm at 19200, also no difference..

              Thank You for the Link..

              THANK YOU Marty
              Last edited by Marty; April 14, 2020, 07:18 AM.

              Comment


                #8
                Yes we are all fine this side of the pond...

                Sitting in my bedroom working from home...

                I have tracked down I/O port 0EFh (IOBYTE). It is on the S-100 Bus System Monitor (SMB) Board. Do you have one of these cards at all?

                If not, I am having difficulty in seeing how the Z80 CPU card will work with the Serial card you are referring to...

                The CO: routine first reads this I/O port and then branches based upon what it read. If the I/O port isn't there - what will the Z80 read?

                Let's assume it 'falls through' to SDCONO:.

                It checks the status of CONSOL_STATUS (I/O port 0) and sits and waits in a loop until bit 2 is set ('1'). If this port doesn't exist either, what will the Z80 read? The Z80 could, if this port doesn't exist, 'jam' at this point.

                Let's assume everything is OK and the character is output to the TX data port CONSOL_OUT at port 1.

                The Z80 then checks the IOBYTE port (0EFh) again looking at bit 5. If this bit is '0' it will output the character to your SCC chip...

                There are a lot of assumptions that have to be true to get a working Z80 card with the monitor working without the SMB card.

                Dave

                Comment


                  #9
                  Hi All;

                  I have tracked down I/O port 0EFh (IOBYTE). It is on the S-100 Bus System Monitor (SMB) Board. Do you have one of these cards at all?

                  No, I don't have that Board, I'll have to track down the Schematic, and see if I can build it, since at present I don't have the funds to buy it..

                  OK, that Clears up what I need to do or to get to make this Work.. Thank You..

                  Yet, in the back of my memory, I have had at least the Z-80 Board working, a few years ago or so, I just don't remember what I had system wise to make it work (read display)..

                  THANK YOU Marty

                  Comment


                    #10
                    The other solution is to modify the Z80 monitor software so it ignores the IOBYTE and the serial console card and goes directly to your SCC.

                    That could make a more suitable solution for you?

                    Interestingly, the SMB is not mentioned under the "NEW USERS" heading of either the "Starter Z80/CPM system" or the "Better Z80/CPM system" on webpage http://s100computers.com/My%20System%20Index%20Page.htm.

                    John, is what I am saying correct or rubbish before I send Marty off down a blind alley?

                    I have got distracted now by the Dazzler II card and the Cromemco System I have on the bench at the moment...

                    Just taken delivery of an ESP8226. I am going to have a 'play'... I have seen an 8008 and a Z80 CP/M emulator available for it on GitHub. It is so cheap (a few GBP) that I plan to buy a few of them...

                    Dave

                    Comment


                      #11
                      Hi All;

                      Thank You, Dave..
                      The other solution is to modify the Z80 monitor software so it ignores the IOBYTE and the serial console card and goes directly to your SCC.

                      That could make a more suitable solution for you?
                      Ok, so I need to see about making my Eprom Programmer work with an XP System.. Which I have to build..
                      That should keep me out of trouble for awhile, Thank You Dave.. The software for the Programmer is workable only on an XP system and nothing newer software wise is available..

                      THANK YOU Marty

                      Comment


                        #12
                        I hopped over to www.asm80.com. Created a Z80 project called Monitor.Z80. Imported the source code into the blank file.

                        Had to do a little conversion to suite the assembler:

                        TRUE EQU 0FFh ; Instead of NOT FALSE.

                        Remove all occurrences of @ and $ symbols in labels and variables.

                        Remove the extraneous "A," from "OR A,...", "AND A,..." and "XOR A,..." lines.

                        Fix a missing comma between the string "Menu Error" and CR.

                        It seems to assemble OK and generates a listing and HEX file. You should be able to compare these to what you currently have for equality before you start to hack about with the code...

                        Dave

                        Comment


                          #13
                          I have hacked the monitor (I notice the text file is V5.5) to use the SCC only.

                          I seriously hacked CI, CO, and CSTS.

                          I also had to move the sign-on message, as the SCC is initialised AFTER the sign-on message is printed...

                          I am busy for the rest of the evening now, so I will forward on to you tomorrow.

                          Dave

                          Comment


                            #14
                            Hi All;

                            Dave, Thank You for a job well done, even if it's not finished as of yet..

                            I am making an attempt to Install Windows XP on a Dell machine, hopefully, that will be another step in the correct direction for me..

                            Talk to You tomorrow, when I hope we Both have something to report..

                            THANK YOU Marty

                            Comment


                              #15
                              Originally posted by Marty View Post
                              Hi All;

                              Dave, Thank You for a job well done, even if it's not finished as of yet..

                              I am making an attempt to Install Windows XP on a Dell machine, hopefully, that will be another step in the correct direction for me..

                              Talk to You tomorrow, when I hope we Both have something to report..

                              THANK YOU Marty
                              Marty,

                              I have a TL866 and if you send me the updated HEX file and what eprom (2716, 2732 etc) you need programed I'll see if I can burn the chip for you and somehow work out how to get it to you.

                              Don B.
                              Crazy old guy with a basement full of Pentium 1 laptops and parts

                              Comment

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