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XT-FDC project level of interest

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    #16
    I would definitely be interested in this board. I would purchase/build a couple of them for sure!

    Comment


      #17
      8 bit Cards that support the higher throughput needed for high density or even ED drives are rare as hens teeth -- hell yeah, I'm all for supporting this one.

      Particularly if it can be made to work in a Tandy 1000 SX.
      From time to time the accessibility of a website must be refreshed with the blood of owners and designers. It is its natural manure.
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        #18
        Originally posted by pearce_jj View Post
        BTW re ROM, is there a preference for the chip type? The SST39SFxx chips are very cheap and readily available, compared to 28C series EEPROM.
        Hi

        Sorry, I am not understanding. The 28C64 are common inexpensive 8KB devices

        http://www.jameco.com/webapp/wcs/sto...10001_74827_-1

        The SST39Fxx chips are fine devices but seem like massive overkill for this simple project. Chuck only needs 4-8KB for the BIOS. The prices seems roughly equivalent too. Maybe this is a regional thing?

        http://www.digikey.com/product-detai...PHE-ND/2297826

        Personally, I wouldn't bother with either of those chips though and just burn an 2764 EPROM. They are so cheap as to be disposable and ubiquitous. Heck, pick them out of the garbage! They'll work fine and are almost indestructable.

        Thanks and have a nice day!

        Andrew Lynch

        PS, lets see what Chuck thinks on the topic. I can change the design easily enough that I don't feel passionate one way or the other. They are both cheap parts.

        Comment


          #19
          Originally posted by deathshadow View Post
          8 bit Cards that support the higher throughput needed for high density or even ED drives are rare as hens teeth -- hell yeah, I'm all for supporting this one.

          Particularly if it can be made to work in a Tandy 1000 SX.
          Hi

          Well if you want to thank someone (or blame someone) then dpatten "lit the fuse". Its about three messages down the list or so.

          http://www.vintage-computer.com/vcfo...card-I-on-eBay

          He is right though. This is an opportunity for a community project like XT-IDE if we can get our act together.

          Thanks and have a nice day!

          Andrew Lynch

          Comment


            #20
            Originally posted by deathshadow View Post
            8 bit Cards that support the higher throughput needed for high density or even ED drives are rare as hens teeth -- hell yeah, I'm all for supporting this one.

            Particularly if it can be made to work in a Tandy 1000 SX.
            Hi
            If compatibility with the Tandy 1000 SX is a priority then you'll have to personally participate in the prototype build and test phase. Otherwise there would be no compatibility testing or debugging done. I don't have a Tandy 1000 SX computer and Chuck probably doesn't either. Thus the need for community involvement!

            Thanks and have a nice day!

            Andrew Lynch

            Comment


              #21
              Originally posted by lynchaj View Post
              I guess I've adopted John Monahan's philosophy of one function per board. It makes for a much simpler design and a *lot* easier to debug. Also I think there would less interest in a combination board rather than a single function boards.
              The UNIX "worse is better" approach! Agreed, single-function is highly desirable in systems that have ample expansion slots.

              Does anyone know if the PC8477B fully supports FM mode? The datasheet says it "can't be guaranteed through functional testing," which sort of sounds like, "it's in there, but we're not testing it because no one cares about FM mode to spend the money on testing" (which is probably valid for 99% of end users). That would make the XT-FDC a better option than my current pick of Adaptec 1522A cards for SSSD 8" disk writing.
              Check out The Glitch Works | My Retro Projects | Vintage Computer Services | Glitch Works Tindie Store -- Vintage Computer Kits and More

              Comment


                #22
                Originally posted by glitch View Post
                The UNIX "worse is better" approach! Agreed, single-function is highly desirable in systems that have ample expansion slots.

                Does anyone know if the PC8477B fully supports FM mode? The datasheet says it "can't be guaranteed through functional testing," which sort of sounds like, "it's in there, but we're not testing it because no one cares about FM mode to spend the money on testing" (which is probably valid for 99% of end users). That would make the XT-FDC a better option than my current pick of Adaptec 1522A cards for SSSD 8" disk writing.
                Hi
                I have no idea. That's a better question for Chuck who is familiar with the PC8477B capabilities. I can only go by what the datasheet says at this point.

                Thanks and have a nice day!

                Andrew Lynch

                Comment


                  #23
                  Could you add hardware to read and write copy protected disks? Now that would be truly awesome.
                  My Retro Computing and Vintage Gaming Blog : http://nerdlypleasures.blogspot.com/

                  Comment


                    #24
                    Yes (I thought I've stated that several times in other threads as well as this one). It supports FM, unlike it's pin-identical cousin, the Intel i82077AA-1. When I contacted Intel about them breaking the FM support when the 82077AA-1 update was brought out, they didn't think it was worth fussing about. Usual Intel attitude.

                    When Intel started shipping the AA-1, Microsolutions recalled all of the CC IV cards so that they could swap chips. No circuit changes, thankfully.

                    I'll add one other note about controllers. If you need to handle the oddball Cromemco 8" format that uses 50 MFM-encoded sectors of 128 bytes, the only PC compatible controller that can handle that format is the NSC 8273. Fortunately, it's not terribly hard to find.
                    Reach me: vcfblackhole _at_ protonmail dot com.

                    Comment


                      #25
                      Originally posted by Great Hierophant View Post
                      Could you add hardware to read and write copy protected disks? Now that would be truly awesome.
                      Since there are so many copy protection schemes in use don't you think including something like that would involve analysis and re-engineering of all the porposed schemes to be included in this 'hardware' copy protection buster? Did you forget to raise your hand somewhere in this post?
                      PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

                      Comment


                        #26
                        Originally posted by Chuck(G) View Post
                        [snip]I'll add one other note about controllers. If you need to handle the oddball Cromemco 8" format that uses 50 MFM-encoded sectors of 128 bytes, the only PC compatible controller that can handle that format is the NSC 8273. Fortunately, it's not terribly hard to find.
                        Hi Chuck! Thanks! There is room reserved on the PCB for the inevitable feature growth is project will experience. If there is enough demand for it, I think there could be two sockets for the FDC to support the PC8477B and the DP8473 presuming they are fairly similar chips and share most signals. Use jumpers and a local crystal oscillator to customize. Please let me know if you think this is worthwhile.

                        Thanks and have a nice day!

                        Andrew Lynch

                        Comment


                          #27
                          Originally posted by Great Hierophant View Post
                          Could you add hardware to read and write copy protected disks? Now that would be truly awesome.

                          Hi! I think this is outside the scope of the XT-FDC project. Unless Chuck has some "magical rabbit up his sleeve" that can convert the FDC into a bit sampler like Catweasel I don't see this as viable.

                          I do recall working on such a project at one time but it fizzled. It would almost certainly be some kind of high speed uC based design and a completely different project.

                          Thanks and have a nice day!

                          Andrew Lynch

                          Comment


                            #28
                            I think some ISA Catweasels are still available--oddly, more so than the PCI Catweasel.

                            But it's a very different kettle of fish to implement a facility like a CopyIIPC OB--and requires a fair amount of software work.

                            So no--I don't think it's worthwhile to include it.

                            Adding a 52 pin PLCC socket for a DP8473 chip for just a single format seems to be a bit extreme, Andrew. The chip is common enough on Future Domain SCSI controllers, as well as several other brands, such as Ultrastor, so the people who need it aren't completely out of luck.

                            OTOH, if you want to implement the board using an 8473 instead of the 8477, by all means do. They're not that different from a software point of view--the 8473 doesn't support PS/2 or special tape drive mode, but we're not doing a PS/2 controller.

                            The DIP version of the 8473 seems to be more common than the PLCC version. But the DIP version supports only 2 drives. Signal-wise the two are very close, though the 8473 requires an added 4 capacitors and 2 resistors for the PLL filter. Not a big deal--they're small-valued (see table II on p7 of the datasheet)

                            More uselsess information, for whatever it's worth. If you can find a ready supply of the PLCC version of the DP8473 (that's the -V packaging), maybe it's the better choice, but the difference is exceedingly small in terms of utility.
                            Reach me: vcfblackhole _at_ protonmail dot com.

                            Comment


                              #29
                              this might be a odd request but could we extend the ROM socket two pins and add two jumps to allow for bigger ROM's?

                              Comment


                                #30
                                Count me in please, I have an 8 bit hd fdc in my XT which supports 2 drives , love to get a couple for my other machines and supporting 4 drives = awesome

                                Thanks
                                Malc

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