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Intertec SuperBrain ROM Dumps

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    Here's my implementation of the TMS2716C reader for modern programmers.


    That's the Superbrain ACT HDD ROM sitting in the socket. Guess what I found when I attempted to read it in my TOP853 programmer?

    SuperBrain V3.1 ACT HDD

    Yep, looks like bit rot hasn't got it yet. And in this ROM we can see the following strings:
    • "3.1 INSERT DISKETTE INTO DRIVE ", and (this is the money shot...)

    The content might not be complete, but there it is.
    Last edited by JonB; April 13, 2017, 06:53 AM.


      That's nice to see! There's hope yet! Have you ever been in touch with that guy in the Netherlands who worked during the 1980's customising Superbrains with non OEM HDs and controllers, forget his name - seemed very knowledgeable if slightly reticent.


        I'm guessing the answer will be yes as a google search led me back here to a long post and a guy named Roland Huissman. Seemed quite the expert, wonder what he'd have to say about your non standard HD setup?


          Very nice JonB!

          What is that adapter board (the PCB itself?)... Looks like something cool to know about.

          Sorry for my delay in reply, but it looks like you have everything sorted out very nicely. Your schematics are very small thumbnails. Any chance to get a slightly higher resolution copy? Might not matter as it seems like you've confirmed they work.

          Are you planning on any runs of the 2816 adapters? If so I might be interested.

          Also, I have to apologize but I really don't remember what EPROM we used in the reader config to read the 2716. I would guess it was either 2516 or 2816. I remember we looked up pinouts of similar size and vintage EPROMs. I guess that you don't need that info, as it appears you read yours already.
          Always read my posts with the highest tone of sarcasm your brain can muster.


            Hi Todd

            The board is a Z80 shim I designed for the uIDE general purpose Z-80 IDE adapter card, hacked about a bit. Read all about it here:


            ..and I will offer these cards to Superbrain owners with suitable drivers, once I have got mine running. Yes, you too can have a whopping 128MB of HDD space available to your Superbrain, maybe, for peanuts. Better days are at hand for Superbrain owners...

            To the TMS27C16 adapters, then. I designed a proper PCB for both host and programmer adapters and sent them to OSH Park for fabrication. There's only three of each at this stage and they are (mostly) spoken for, but it's easy enough to get more. I would need to make sure they work properly first.. and fit; the host adapter doesn't really have enough space inside the Superbrain, unless the original socket is fully removed and the adapter is soldered into its position, but even then..

            You're correct in that I have read my EPROM and it is OK (this is the special ACT HDD ROM). I posted a copy of the dump earlier on. To do this I set the programmer to a 2816 EEPROM and read. Worked first time, with the "red board" adapter (prototype). Since then I hacked up a host adapter out of pin header strips and jump wire, programmed a 2816, shoved it in the Brain's EPROM socket and attempted boot. Naturally, it didn't work! Not becasue the ROM is bad, or the adapter, but because the Brain is sick.

            I have a Z80-ICE here and I can see that memory access is not working properly. I suspect it is something to do with the ROM paging logic. Do you know anything about it? I've been working with ldkraemer on this, he has been looking out for useful info and came up with this stuff from


            In it a chap called Warren W. Gay muses about the EPROM of the Superbrain and how it works with the first and second CPU. I've not read it all, but I am very keen to work out how the memory paging is triggered (probably via I/O ports), then I can check mine is OK. It's frustrating, because all this has been done before, but the information seems to have been lost.

            If you have any information on this, please let me know as I am at a bit of a standstill. The schematic confuses me!

            Last edited by JonB; April 19, 2017, 12:28 AM.


              That shim is awesome. I'll read more on that later.

              Awesome on the adapters, I'll be keeping an eye on this thread.

              I've also noticed the tolerance issues with this computer, so definitely interested to see the fitment of your adapter once it's done.

              Sadly, I don't know anything about the ROM paging logic at this point. Thanks for the link to the Lobotomies. Good name, too. Hahha

              Also, I wanted to cross-post to the other thread where we talked about ROM dumping on the SuperBrain... I posted a link to THIS thread, but not the other way around:

              See ya.
              Always read my posts with the highest tone of sarcasm your brain can muster.


                Thanks Todd.

                It's quite simple, really, but incredibly useful, sometimes. I'll post pictures of the ROM adapters once I receive them and build one of each.

                Meanwhile, I contacted the author of the "Superbrain Lobotomies" posts on comp.os.cpm and he has kindly put his ROM disassembly onto github here:

       case anyone out there can use the information.


                  Superbrain ROM adapter board.. This is the adapter that allows use of a 2816 EEPROM on the Superbrain motherboard without modifying any tracks on the Superbrain. It's based on the reader design presented by EagleTG and dmemphis on this thread.

                  The bare board.

                  Top view, assembled.

                  Bottom view, assembled.

                  In situ with CPU2 on the right.

                  With a 2816 fitted.

                  This rig is not going to fit as-is with the case closed. For that, I think you would need to remove the ROM socket from the motherboard and solder the adapter directly (in the picture it is plugged into the socket). You may also need to solder the 2816 directly to the adapter to save a few more millimetres. I've done a quick trial and it may be OK without removing the socket, but it would need some finessing in the assembly stage.
                  Last edited by JonB; May 4, 2017, 03:18 AM.


                    TMS27C16 reader adapter board.


                    P3 has the tiny voltage converter module soldered to it. U1 is the 7905 5-12v regulator. As the current requirement is so low, I think we can get away with a smaller device such as a 79L05 (which I will be testing). I'm waiting for some of these modules to arrive from China before attempting to build one - don't fancy desoldering it from my prototype (the red board).

                    Once built, you would use this to retrieve the content of your Superbrain ROM using a modern programmer, and setting the programmer for a 2816 EEPROM.

                    There are only three of each type of board at the moment and I think they are all promised out.
                    Last edited by JonB; May 4, 2017, 03:29 AM.


                      Nice work!
                      My double socket plus 2816 IC fits under the case with only a slight impingement.
                      Your adapter should even be less, though it might touch.
                      Its a feature, it holds it in place!


                        I've just acquired a SB II board which I am attempting to nurse back to health. It has a boot ROM labelled 4.2, which appears to be working. Will upload a dump presently.


                          Turns out I already had a copy of this ROM. It came from zippysticks' SB II.
                          Attached Files


                            Here's the UK spec (50Hz) Superbrain II 4.2 ROM
                            Attached Files