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MFM controller for S-100

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    #31
    Originally posted by RickNel View Post
    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
    Actually, it wouldn't be that bad. One of the tricks that has long been used by the microcontroller hobbyists is using an ISA NIC connected to a microcontroller such as an ATMega128.

    You'd want to use a 16-bit (AT Style) MFM controller as those generally don't use DMA for data transfers (which would be a bother). All of the control and status registers in an AT controller are 8 bit; only the data path is 16 bit. If you didn't mind tossing half of each 512-byte sector out the window, it'd be pretty simple. It'd actually be harder to interface to the floppy part of a MFM HD-floppy controller.

    Heck, if someone can make a USB-to-ISA adapter, S100-to-ISA should be easy.
    Reach me: vcfblackhole _at_ protonmail dot com.

    Comment


      #32
      OK - thanks. You've given me a reason to look harder for documentation on the Wang ISA controller (ISA on 386 AT-like motherboard but not PC-compatible - zero documentation so far).

      The sector size issue - perhaps could be handled by buffering in RAM, the way CP/M systems commonly buffer 2 x 128b CP/M records for read-write to 256b FDD sectors?

      I still haven't been told that an all-software solution is not possible as well.

      Not rushing at this... it's waited 20yrs so far so can wait a while longer.

      Comment


        #33
        Originally posted by RickNel View Post
        I still haven't been told that an all-software solution is not possible as well..
        Well, no, for an MFM drive, you have to be able to service a raw bitstream at 5MHz , which is way faster than any of the "vintage" machines will go. And that raw bitstream uses differential signaling.

        On the other hand, interfacing an IDE drive to a pair of parallel ports might well be possible on an S100 system without much other than some cabling and a suitable power supply for the drive.
        Reach me: vcfblackhole _at_ protonmail dot com.

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          #34
          Right - that settles it then, those bitstream specs mean there's no hope of avoiding a hardware controller on a system chugging along on 4MHz CPU!

          Looking at the Wang controller board , I see a WD11C00C-JU controller chip (same as used on IBM AT-5150 I believe), and three crystals at 16MHz, 10MHz and 9.6MHz.

          Google hasn't heard of this controller card: HFA-100.W2 P/N 96-0000-1080-2. Any suggestions on suitable docs repository? Docs for a similar card for IBM AT-5150 might help somewhat.

          Comment


            #35
            Originally posted by RickNel View Post
            Google hasn't heard of this controller card: HFA-100.W2 P/N 96-0000-1080-2. Any suggestions on suitable docs repository? Docs for a similar card for IBM AT-5150 might help somewhat.
            A photo might help--often these things followed a generic design.
            Reach me: vcfblackhole _at_ protonmail dot com.

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              #36
              hdc mfm

              Hi all;
              I have an s-100 hdc controller that was built especially for miniscribe, I have No information it, it has plenty of extra ic's more than the average controller for a hard disk controller.
              Thank YOu Marty

              Comment


                #37
                DTC made S100 SASI adapters, I used them to interface to Xebec 1410's. I still have the DTC manuals and BIOS and utilities source code, don't think I have the SASI S100 schematic though. However, SASI is quite simple, a subset of SCSI.

                This link seems to be a good starting point? Lists many controllers, and even art work for a host adapter.

                Gerrit

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                  #38
                  Old thread. Got it.

                  i just got a s-100 disk controller for a Corvus Systems hard drive. Photos are here
                  I'm looking for a serial to MFM controller. Anyone know of such a device? I figured a serial connection would be the most universal, and wouldn't limit to just one retro system.

                  Comment


                    #39
                    Originally posted by fibrewire View Post
                    Old thread. Got it.

                    i just got a s-100 disk controller for a Corvus Systems hard drive. Photos are here
                    I'm looking for a serial to MFM controller. Anyone know of such a device? I figured a serial connection would be the most universal, and wouldn't limit to just one retro system.
                    Not sure what you're asking here; you ask what that controller's for? Not to be a smart ass, but presumably to interface a Corvus hard disk to an S-100 system like the Zenith that you mention...

                    As to the "serial" connection, far from being "universal" I can't think of *any* retro system off-hand that could use a serially-connected MFM drive without some serious driver writing except perhaps the Corvus drives, but they're hardly any "standard" serial interface...

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                      #40
                      I typed out a lengthy explanation, but accidentally clicked the back button on my Microsoft Natural Wireless Laser Mouse 7000. Probably the better half of 30 minutes was spent creating my reply. I will answer your question shortly, as i need to take a brisk walk to the coffee machine.

                      Comment


                        #41
                        Originally posted by fibrewire View Post
                        I typed out a lengthy explanation, but accidentally clicked the back button on my Microsoft Natural Wireless Laser Mouse 7000. Probably the better half of 30 minutes was spent creating my reply. I will answer your question shortly, as i need to take a brisk walk to the coffee machine.
                        Been there, done that, T-shirt hanging in the closet, and feel your pain; hope there's something in your bottom desk drawer to fortify the coffee a bit

                        Comment


                          #42
                          Is there a shortage of MFM controllers for the ISA bus? Since most of the (16-bit) ones, use PIO for data transfer (not DMA), might it not be more interesting to simply make an S-100-to-ISA adapter? You then get the entire range of ISA peripherals at your fingertips. Just write the drivers...
                          Reach me: vcfblackhole _at_ protonmail dot com.

                          Comment


                            #43
                            I am exploring a ST-506 to some standard interface. Then from the standard interface to your choice of retro computer interface.

                            Apparently the MFM to SASI interface already exists. This whole idea spawned from having a Corvus Systems hard disk with no interface to any computer. I just purchased a S-100 corvus interface, but I am waiting to see if it's works. I would really like a Corvus SYstems hard disk to Atari interface, but that seemed next to impossible. A guy from AtariAge said he could help, so I am gonna wait for now. What would really be cool is a SASI to USB interface. Then we could access all the rare data stored all over ebay. Hell, I would have a field day buying old drives on the cheap and seeing whats on them.

                            There are easier solutions i'm sure, but learning how ST-506 works would be a cool way to cut my teeth on electronics design.

                            Comment


                              #44
                              MikeS: You had mentioned that SASI is little more than a parallel port. Is there any information you can point the way to how SASI works? I would really like to see a SASI to Atari SIO or SASI to S-100.

                              Comment


                                #45
                                Hi! I'd be willing to help make a PCB for a S-100 to ISA board assuming someone can send me a schematic. I believe this would be a lot more than just connecting the address and data busses. There would need to be some kind of signal translation for the control signals between the S-100 and ISA busses.

                                I am pretty swamped at the moment with other S-100 and ECB related projects so this would have to be a community effort along the lines of the boards John Monahan and I have made. The group approach has worked well for our boards, the S-100 68K CPU board, and a variety of other projects. Also working with Rich on a S-100 6502 CPU board.

                                Thanks and have a nice day!

                                Andrew Lynch

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