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Debugging a KIM-1 computer

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    Oops, it is A8 and A9 that may not be decoded. I need
    to change my wiring.
    I'll confirm that.
    Good catch.
    Luckily I haven't finished that part of my hand wired adapter.
    I'll move the wires and have another diagram.
    Last edited by Dwight Elvey; November 14, 2016, 08:17 AM.


      Originally posted by Dwight Elvey View Post
      Is there any interest?

      I responded to you on the classiccmp list but just in case please put me down for one! Thanks!
      Current Wish List: 1. IBM 7531 Industrial Series PC 2. NEC MultiSync XL (JC-2001) Monitor 3. MicroSolutions UniDOS card 4. Compaq 14" VGA CRT Monitor (the one that came with the SystemPro). 5. Stacker HW CoProcessor Board MCA BUS. If you have any of the above for sale please PM me. Thank you!


        Originally posted by Dwight Elvey View Post
        Oops, it is A8 and A9 that may not be decoded. I need
        to change my wiring.
        I'll confirm that.
        Hi Dwight,
        Yes, A8 and A9 too, but to me it looks like A6 and A7 also determines selection of both the correct 6530 and its I/O function. Very confusing. It seems the KIM-1 used 6530s with different 6530 mask address decoding.

        It saved them some glue logic on the KIM-1, but left it a little difficult to replace them with the generic 6532.


          I'd be interested as well, thanks!

          - Gary


            Your right Dave, I don't know how I got that part wrong. At least for my
            wired up adapter, I can ignore A8 and A9 but I'll need to keep them for the main
            I'll have to reevaluate what I'll do for decoding there. It may be two chips or
            a 16L4 type device.
            I need to think about it. As it is now, it is clearly wrong.
            Last edited by Dwight Elvey; November 14, 2016, 10:15 AM.


              Hi Dave
              It is funny that I'd originally bought a 74138 with intentions
              of using that. When I started the drawing I couldn't recall why I'd
              bought it.
              I still need an inverter for the R/W on the EEPROM or I'll not be able
              to do in place programming. I'd really like to keep that.
              I just realized that K6/7 is OK for reading but needs CLK2 for writes.
              I have some cleanup to do.
              Last edited by Dwight Elvey; November 14, 2016, 11:12 AM.


                With the 74138 you can do some quite elaborate decoding, it has three direct 'address bits' and two active low and one active high level 'enable' line, all 8 outputs are active low (for /OE, /CS, /RD or /WR etc)..


                  Originally posted by Dwight Elvey View Post
                  I'll have to reevaluate what I'll do for decoding there. It may be two chips or
                  a 16L4 type device.
                  I really hope you can keep your elegant design concept of stacking everything using only the 6532 40 pin footprint.

                  The GAL16V8 can be obtained in small outline (SOIC) and PLCC packages if needed to make everything fit. I would have to build some surface mount-to-DIP adapter in order to program them. It is more than enough to do all the address decoder/glue logic in one part. Looking at ebay, the PLCC is the most common surface mount package and can be bought for less than a buck in very small quantities.

                  A real drawback is that the kit would have to come with a programmed GAL as it can't be expected that all the users would have the capability to program PAL/GALs.


                    I'm going to go with one 7404 and one 7400. I should still be able to keep
                    it small.
                    It looks like a minimal gating takes 5 inverters and 3 nands. That includes
                    the gating needed for the EEPROMs WE*.
                    I'll update the drawings tomorrow.
                    The SOIC ttl parts are really small.
                    I looked at using the 74138 but it didn't solve the EEPROM write problem.
                    It needs either the WE* or the CE* qualified with CLK2. It doesn't make
                    sense to add it to CE* because one wants to not have it for the read.
                    It is needed for the write though.
                    I looked at the 6502 timing and there should be no issue programming the
                    EEPROM. I'll probably write code for the D7 compliment write testing.
                    I'm really pissed at myself for messing up the decoding.
                    That is why one does a prototype of every thing.


                      Originally posted by Dwight Elvey View Post
                      I'm going to go with one 7404 and one 7400. I should still be able to keep
                      it small.
                      Good work. If you can keep the footprint without the need for a PAL/GAL, so much the better.

                      I looked on ebay for a KIM-1. Working units are very expensive, while a broken one may have a bad 6530. Your repair kit will be a viable option.


                        I redid the schematic but forgot to hit the send button. It'll have to wait for

                        Got it now.
                        Dave, you have a good eye, can you review it?
                        I have a few redundant wires shown that are in the first drawing.
                        If I get time, I'll delete them in the first drawing to remove confusion.
                        Attached Files
                        Last edited by Dwight Elvey; November 17, 2016, 12:35 PM.


                          Originally posted by Dwight Elvey View Post
                          can you review it?
                          Looks good. I think you got it. I was a little confused until I realized CS1 on your schematic is the K5 decoder output on the KIM-1. You may want to denote that on the schematic.

                          To make the 6530 replacement kit a universal design, I think you need add jumper selects into the 6532 CS1, /CS2 and /RS inputs to open the circuits and allow jumpers to any address line that may be required. But more than that I notice that the 6530 in the 4040 disk drive uses pin 19 as a chip enable while the KIM-1 uses pin 18. So cut and jumpers may be needed for some applications anyway.


                            I thought about that but I wanted to keep it simple for the KIM-1 only.
                            Others have made adapters for Commodore stuff. They weren't as clean
                            as this one will be.
                            I've decided to use a PLCC 16L8 instead of the separate gates. It'll add a little
                            bit of height but a lot simpler wiring for the PC. You just bring the wire to
                            whatever input you'd like to use. The only restricted areas are the outputs.
                            One can skip every other pin ( cut them off once programmed ) to use for
                            more routing. Routing is going to be the bigger issue.
                            Also, I wanted to make it so one could change it form -002 to -003 for both
                            the I/O and the ROM. The way it is now it would take another chip to be able to do that.
                            One still has to program both ROM sections but that will be easy with the debug
                            board. The 16L8 is so much more flexible and actually uses less board space.
                            I just wish it were flatter. I can bring more wires to the 16L8 to make it more
                            universal. It could have all the signals use in the original 6530!
                            I've settled on using KiCad. Both cheap and many think it is quite good.
                            CS1 is the proper name of the 6530 pin, when used as a select.


                              The prototype adapter is working, at least for the first level. My display test works.
                              Now for my next trick to see if I can write to the EEPROM.
                              I may still have other issues but it is a lot easier to check things with a
                              working monitor. I will continue to write more EPROM drive test. It is just that
                              things are so much easier if I know all is working.
                              I'd bought some cheap 6532s from China. The first one was dead so I suspect
                              something else may be bad in the part that is working so far, maybe RAM or timer.
                              I was worried the there was something wrong with the adapter ( some 50 or so
                              crossed wires ).
                              Still, a working KIM monitor will make the job a little easier than not knowing if
                              there was a problem in my code or in the hardware.


                                Originally posted by Dwight Elvey View Post
                                I wonder if anyone has the firmware for the TIM?