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Thread: Flash based - MFM Drive Emulator

  1. #41
    Join Date
    Feb 2010
    Location
    40 Km South of Paris, France
    Posts
    162

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    @ LOU,
    That is very surprising !!
    You just wrote ALMOST what I had in mind when I logged, today, on this forum !
    So, I have anything more left to write
    This is frustating.
    More seriously, this rise a question :
    What ADVANTAGE your projet has versus Reinhard's DE0 Nano based RL emulator ??
    As English is not my native language, I would like make clear what I want to express :
    As I had almost the same idea you had when in logged in, and after (re) discovering Reinhard's emulator,
    I am NOW asking myself : " Is there any fun left in going on with this project ??
    Understand what I mean ??
    BTW, shall I recall that I a newbie to this community, owning a 11/23 plus ( bought this month, and of course, my very first PDP ) and that I am in the process of resurrecting ( fixing and testing ) the power supply.
    That's mean : I am just at the beggining of the road
    but expecting of a lot of "fun" along it ...

  2. #42
    Join Date
    Mar 2008
    Location
    Westchester County, NY
    Posts
    1,183

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    Gerard,

    It is easy to write, but not easy to do. At the moment, have no partcular need to do it either (RQDX3 based SMD9224 replacement disk emulator), since Reinhard's project needs only a little more troubleshooting to be perfected. So, I think the project I suggested above really has no advantage unless you do not have an RL11/RLV11/RLV12, but only have RQDX3.

    I do think it would indeed be a fun project however, but would probably take a year of hobby time. Reinhard has spent about two years working on his project. It took me about five months of hobby time just to build a duplicate of his work (but it was worth it!)

    It was probably about seven years ago that I started playing with my dec hardware again. With every project or restoration, I learn a little more.

    By the way, I am reminded that about a year ago, I drafted a document that explains how to patch ZRQCH0 using UPDAT to use ANY geometry MFM hard disk, not just RDxx disks. There are bits and pieces of how to do this floating around the internet, but I wanted to explain how to do it from soup to nuts. I sent a preliminary copy to someone for them to review, but can't remember getting feedback. If anyone would like to review the draft, they can send me a PM with a proper e-mail address and I will send it to them. I request that they tell me about all errors and do not forward it, so that an error-free version can be published eventually.

    Lou

  3. #43

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    I know this is an old thread.... and not sure if someone's mentioned it.. But I found this!!! https://www.drem.info/ and I may buy one myself soon... just spreading the word!

  4. #44

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    Quote Originally Posted by aplmak View Post
    I know this is an old thread.... and not sure if someone's mentioned it.. But I found this!!! https://www.drem.info/ and I may buy one myself soon... just spreading the word!
    Thank you!

    For the price they're asking (around $325 USD shipped) it seems like a more reliable and cheaper option than my thought of getting a QBUS SCSI controller and drive which would have cost me around $500 for used components. My RD52A drive is working... for now... but since the drive looks like it has been refurbished/repaired 3 times now (based on the flag list stickers piled up on each other), something tells me I need to take that drive out and keep it as a collectible piece (or sell it) instead of relying on it if I'm to put my PDP up on HECnet.

  5. #45

  6. #46

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    There's also David Gesswein's MFM hard drive reader and emulator:

    https://www.pdp8.net/mfm/mfm.shtml

  7. #47

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    Quote Originally Posted by Alphasite View Post
    There's also David Gesswein's MFM hard drive reader and emulator:

    https://www.pdp8.net/mfm/mfm.shtml
    Thanks! That is probably what I would try first since it’s lower cost and I don’t need the multiple drive/file feature of the first unit.

    It’s funny to think I used such an emulator that was built in 2003 before I ever realized I’d do this as a hobby. The system I worked on in the Navy was a Unisys based mainframe that originally used tape drives (7-track) and Seagate MFM drives on one system and the old HUGE disk pack drives on another system. They were replace by a Lockheed designed Solaris based emulator which took those drives and emailsted them in software and put them out over the NTDS parallel bus already on the mainframe. The software was not classified by definitely proprietary to the DOD but was one of many cases where we had emulated hardware of the sort. Another system was a DOS based system that emulated a 9-track tape system which I regularly used as well.

    Best part of those systems was it took a 15 minute cold-load and turned it into a 30 second cold load of the mainframe OS because of how efficient the emulator was. So I am excited to see how these setups would perform in place of an MFM drive.

  8. #48
    Join Date
    Dec 2010
    Location
    Seattle, WA
    Posts
    1,545

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    Quote Originally Posted by NavyBOFH View Post
    For the price they're asking (around $325 USD shipped) it seems like a more reliable and cheaper option than my thought of getting a QBUS SCSI controller and drive which would have cost me around $500 for used components.
    You can get an Emulex UC07 Q-bus SCSI controller for $239
    https://www.ebay.com/itm/Emulex-UC07...2/142506787590

    Hard drives that will work with that should not be very expensive.

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