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MFM controller for S-100

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    #16
    Your IMSI hard controller sounds like an SMD interface, not ST506 or SASI. Just a guess, however.
    Reach me: vcfblackhole _at_ protonmail dot com.

    Comment


      #17
      Yesterday I got the cover off my TeleVideo machine, and inside it had a similar adapter for connecting the HDD. Floppy connector (A flat one, you plug the floppy-end of the cable into it) in one end, and MFM hdd connectors in the other end.

      Maybe they're quite common after all..

      The TeleVideo is a multi-user Z-80 machine, but not S-100
      Current machines:
      PCs: IBM PC XT 640K, IBM PC XT 256K ,IBM PC XT , 2x IBM PC AT, Compaq Portable I, Compaq Portable II, Compaq Portable I/286, Philips Logic Analyzer XT clone, IBM PS/2 Model 30 286 , HP 95X, HP200LX (2x),Compaq SLT/286.
      Apple: Macintosh 512k, Macintosh SE, Macintosh Classic, PowerBook 170, iBook Clamshell, iBook G3,iMac G4 , TiBook's, Apple IIc, Many newer machines (G4, G5, Intel..), 20th Anniversary Mac
      Others: Commodore 64C,Amiga A500, CCS S-100 System, SNES,

      Wanted: Macintosh 128k, Hard Disk 20, System disks and games for the Mac

      Comment


        #18
        Hey, an update on the MFM S-100 controller.

        I have here the Cromemco STDC, which is a S-100 bus ST-506 controller

        This is exactly what you are looking for right ?

        The link to the manual is here

        It was in a pile of other misc cards I got from my haul.
        Current machines:
        PCs: IBM PC XT 640K, IBM PC XT 256K ,IBM PC XT , 2x IBM PC AT, Compaq Portable I, Compaq Portable II, Compaq Portable I/286, Philips Logic Analyzer XT clone, IBM PS/2 Model 30 286 , HP 95X, HP200LX (2x),Compaq SLT/286.
        Apple: Macintosh 512k, Macintosh SE, Macintosh Classic, PowerBook 170, iBook Clamshell, iBook G3,iMac G4 , TiBook's, Apple IIc, Many newer machines (G4, G5, Intel..), 20th Anniversary Mac
        Others: Commodore 64C,Amiga A500, CCS S-100 System, SNES,

        Wanted: Macintosh 128k, Hard Disk 20, System disks and games for the Mac

        Comment


          #19
          Looks like it. I note that the documentation mentions no other OS except Cromix. Do you have any driver software for it?
          Reach me: vcfblackhole _at_ protonmail dot com.

          Comment


            #20
            Cromemco STDC

            The control and data cable connectors match the NEC D3142, but its hard to see how this card could run between CP/M and the NEC HDD. Unless Cromemco had a CP/M implementation for it with a different manual.

            Even so, that Interrupt Priority Cable looks scary - is that a feature of Cromix-based systems or Cromemco generally? Not compatible with my system as far as I can see... Interrupts are all handled through the bus and system I/O card. This manual seems customized for a particular HDD with no other options.

            Would there be workarounds?

            Comment


              #21
              Reading the STDC manual, it's an interesting beast.

              What sticks out first is that no sectoring is done on the hard disk--each track is handled as a single long sector of about 10K. The board has 64K of memory and the docs say that there are 4 read/write buffers and 1 verify buffer (that would amount to 50K of the 64K). Can you say "blocking and deblocking code"?

              It's not clear if you can access the buffers using programmed I/O or if DMA is required. If the latter, I can see problems ahead. DMA was one of those things that was extremely variable between vendors. It might be possible to get the board to work without interrupts, however.

              Like a lot of Cromemco stuff (particularly the later stuff) is somewhat scarce on programming information and this board is no exception. It was made to run with Cromix (no mention of CP/M is given).

              Maybe Herb Johnson at Retrotechnology has programming information. Otherwise, if you're set on using the board, you'll have to do your own reverse engineering.
              Reach me: vcfblackhole _at_ protonmail dot com.

              Comment


                #22
                Yeah, that's what I was saying earlier: it's not your average ST506 controller, but a 64K Z80 computer with 8K of ROM and a number of undocumented PROMs. AFAIK not even the latest versions of CDOS (Cromemco's version of CP/M) could talk to it, only 68K Cromix and the last few versions of Z80 Cromix, and other than the sparse manual and system-level calls I've also never seen any detailed technical info. The interrupt priority jumper would be the least of your challenges.

                Like I said, unless you have a Cromix system I'd think that it'd be a major challenge to use an STDC in a CP/M system. There is a test/exerciser program for the STDC/ST506 HD; I suppose if you could rig up something to snoop the bus while issuing commands you might learn something useful, but I think one of those SASI<>MFM bridge boards would be a lot easier, while a Cromemco owner might be able to appreciate the STDC much more.

                The STDC and DPU are relatively rare, so if Quantum can find an FDC and memory card to go with them he's got the makings of a pretty good Cromemco system.

                Comment


                  #23
                  With a schematic and the PROM, it could certainly be reverse-engineered. The problem is that it might as well be a one-of-a-kind deal that's going to take a lot of work to get going. I don't much care for the "sector-is-a-track" approach either.

                  I'd sooner use a generic parallel I/O interface to talk to a SCSI or IDE hard drive.
                  Reach me: vcfblackhole _at_ protonmail dot com.

                  Comment


                    #24
                    Originally posted by MikeS View Post

                    The STDC and DPU are relatively rare, so if Quantum can find an FDC and memory card to go with them he's got the makings of a pretty good Cromemco system.
                    I found both on ePay, but very expensive.. I will have to look for more cromemco boards the next time I take a trip to the place I got them.

                    I think this controller will be placed in a parts box, and I'll focus on getting my CCS S-100 machine do something more than spin a fan and light up a led.
                    Last edited by QuantumII; May 27, 2009, 11:17 PM.
                    Current machines:
                    PCs: IBM PC XT 640K, IBM PC XT 256K ,IBM PC XT , 2x IBM PC AT, Compaq Portable I, Compaq Portable II, Compaq Portable I/286, Philips Logic Analyzer XT clone, IBM PS/2 Model 30 286 , HP 95X, HP200LX (2x),Compaq SLT/286.
                    Apple: Macintosh 512k, Macintosh SE, Macintosh Classic, PowerBook 170, iBook Clamshell, iBook G3,iMac G4 , TiBook's, Apple IIc, Many newer machines (G4, G5, Intel..), 20th Anniversary Mac
                    Others: Commodore 64C,Amiga A500, CCS S-100 System, SNES,

                    Wanted: Macintosh 128k, Hard Disk 20, System disks and games for the Mac

                    Comment


                      #25
                      I'd recommend that you get the Xebec hard/floppy (if that's what it is) controller going. It should be a fairly easy job as most of the "smarts" are on the board, not on any S100 card.
                      Reach me: vcfblackhole _at_ protonmail dot com.

                      Comment


                        #26
                        Yes, if I ever get the S-100 system running I could try to get it running.

                        See my thread CCS S-100 Woes on what I'm struggling with at the moment.
                        Current machines:
                        PCs: IBM PC XT 640K, IBM PC XT 256K ,IBM PC XT , 2x IBM PC AT, Compaq Portable I, Compaq Portable II, Compaq Portable I/286, Philips Logic Analyzer XT clone, IBM PS/2 Model 30 286 , HP 95X, HP200LX (2x),Compaq SLT/286.
                        Apple: Macintosh 512k, Macintosh SE, Macintosh Classic, PowerBook 170, iBook Clamshell, iBook G3,iMac G4 , TiBook's, Apple IIc, Many newer machines (G4, G5, Intel..), 20th Anniversary Mac
                        Others: Commodore 64C,Amiga A500, CCS S-100 System, SNES,

                        Wanted: Macintosh 128k, Hard Disk 20, System disks and games for the Mac

                        Comment


                          #27
                          ST506 driver code

                          Reverting to my original topic...

                          MikeS suggested crafting up an interface to a parallel IO card.

                          I notice that Howard Harte has contributed open source code for an ST506 controller for the SIMH AltairZ80 emulator environment.

                          http://simh.sourcearchive.com/docume...8c-source.html.

                          This would be a useful start for anyone looking to build an ST506 software driver, highly configurable, maybe without the need for a separate controller card. Just speculating.

                          I'm guessing there would be I\O speed limitations, but is there any other factor that would make that approach unworkable?

                          Rick

                          Comment


                            #28
                            I don't follow (I'm probably very thick today)--the SimH driver given is for a CompuPro Disk3 card. Do you have one of those or a CP/M configured to run with that and the cards on your CCS?
                            Reach me: vcfblackhole _at_ protonmail dot com.

                            Comment


                              #29
                              Not thick

                              Chuck - you are not thick but I am new to a lot of this, so forgive me if I have to start by asking dumb questions.

                              Quantum has the CCS - I started this thread in relation to my IMS which has similar configuration, but NO s-100 MFM controller card, just an ISA bus ST506 controller from a dead Wang PC.

                              To clarify - my last post was asking whether it could be possible to craft a driver that would directly address an ST506 drive (eg my NEC D3142) connected via the parallel port on a S-100 system.

                              MikeS suggested the port could be used that way, in context of a bridging card. If I wanted a season in Hell, I could think about trying to bridge my ISA controller to the S-100 bus.

                              I'm not suggesting the SIMH Disk3 driver would do the job as is, just that the code might provide at least part of what is needed to make a purely software interface. I understand that the SIMH Disk3 emulator emulates the whole drive system, not just a driver for a real Disk3 card. Do I have that wrong?

                              What I don't know is whether the controller cards do anything that could not be emulated in software using RAM and a typical S-100 I\O card. In the end, the ST506 interface is two data pins and a bunch of control pins. Is it possible that the buffering and control register handling that is typically done on a controller card could be set up in system RAM and directed through the parallel port?

                              If the answer is straight NO, I'll keep looking at other solutions, but this thread suggests there are no easy answers.

                              Rick

                              Comment


                                #30
                                I think yes this is possible. I have an S-100 system with a non S-100 hard drive controller myself. It depends on the card, but you may have to add/remove things like voltage regulators, etc. It'd be a project.

                                Here is a link I refer to time with some good info on ST506 interfacing. Kelly L sent it to me in early 2006. It does not directly apply to your project, but it may help.

                                http://nemesis.lonestar.org/computer...orage/mfm.html
                                Last edited by billdeg; June 11, 2009, 05:07 PM. Reason: gdsgs
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