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Thread: Putting together my first PDP (Need some help)

  1. #11
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    Quote Originally Posted by Matlock View Post
    I assume you might be thinking about a SCSI2SD card? If so I highly recommend getting two of them.
    I follow these small qbus system builds such as this one, saipan pete's, diane's and the LSI11box with much interest as I have enough of the same components to put perhaps two together.
    Can I ask you for a recommendation on which SCSI2SD board suits these machines + UC07 best? There seems to be a few different offerings on eBay. I may be mistaken but I thought I'd read on this forum that certain revisions on some SCSI2SD's worked better than others?
    Thanks
    Steve.

  2. #12

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    Quote Originally Posted by Matlock View Post
    You didn't mention what you intend to use for a disk, but given you plan to use a SCSI controller, I assume you might be thinking about a SCSI2SD card? If so I highly recommend getting two of them. That way you can do disk to disk backups to a totally separate SD card. It's pretty easy to make a mistake when transferring software from a simh image to the SDcard especially if you format a number of disk images on each card. The SCSI2SD approach is fantastic to get started because you can build your disk images on a PC with simh then dd them to the card and then boot straight into them. The two SDcard approach also allows one to be more adventuresome with new software. Do a backup just before you do some new installation and if things don't go well you can run a restore from your backup.
    Good Luck,
    Mark
    The SCSI2SD is part of the plan, but I wanted to make sure the system is working before I made that purchase. My budget isn't the largest and I didn't want to spend and additional $70 on a system that doesn't boot. I have a serial adapter to use my PC as a tape drive via emulation. Once I have that sorted, I plan to purchase the SCSI2SD.

  3. #13
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    Quote Originally Posted by 1944GPW View Post
    I follow these small qbus system builds such as this one, saipan pete's, diane's and the LSI11box with much interest as I have enough of the same components to put perhaps two together.
    Can I ask you for a recommendation on which SCSI2SD board suits these machines + UC07 best? There seems to be a few different offerings on eBay. I may be mistaken but I thought I'd read on this forum that certain revisions on some SCSI2SD's worked better than others?
    Thanks
    Steve.
    I would recommend the V5.1 SCSI2SD with UC07 for PDP-11s. I have used his V3, V4, V5.0, V5.1 and V6 units and the only one that gave me trouble was the V6, but I think that may be fixed in the latest software upgrades. My recommendation of the V5.1 model is based on it uses full sized SDcards which are much easier to insert when mounted in one of the 5 1/4 mounting frames and in my testing of V5.1 versus V6 for a PDP-11 / UC07 combination there is no measurable difference in speed. Given that the V6 is considerably more expensive the V5.1 is the best choice.

    If you are in the U.S. Inertial Computing is a good place to buy them: https://store.inertialcomputing.com/category-s/100.htm
    In Austrailia you can get them from the creator: http://www.codesrc.com/mediawiki/ind...?title=SCSI2SD

    I've used the UC07 / SCSI2SD with 11/23+, 11/73, 11/83, 11/93 (actually Mentec M100-04) and a MINC 11/23 but that required a BDV11 with EPROMs from an 11/23+. I've also used the SCSI2SD with VAXstation 4000/90A, MV3100-80 and MV3100-30.

    Best,
    Matlock

  4. #14
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    You could also build one of my RLV12 Emulators , although it gives you only 4 x 10Mbytes of disk storage. But if you are willing to spend the money for a UC07 and a SCSI2SD I would also recommend the 5.1. The problem with the 6.0 is that it in fact emulates the synchronous 10Mbyte SCSI. In theory a normal asynchronous SCSI controller like the UC07 should work with 10Mbyte synchronous capable disks, bu it is not always guaranteed. I have been running this combination in all sorts of self built PDP-11 systems and it always worked like a charm. What I like the most is that when you configure the CPU board to boot on the power fail vector (24/26) and set the corresponding jumper on the UC07, the UC07 provides the necessary boot code to the CPU (I presume it just loads the boot block via DMA to address 0 and modifies the power fail vector to execute the boot block), so you do not even need a bootrom at all.
    For more information about my projects see https://www.5volts.ch

  5. #15

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    Unfortunately, the chassis and psu I had marked for purchase for this build has been sold, and due to my limited budget, I cannot afford $200+ blackplane and chassis. Even If I got a bare backplane, I do not have a psu, (could possibly get an ATX, but that's still money I don't have) and still, where am I gonna put that big old cpu board without a chassis? I am going to have to shelve this project, unless I can find something that is affordable.

  6. #16
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    Fantastic, thanks Matlock and cbscpe for your detailed evaluations, that really helps a lot, and I guess it will help Mr Skullmeat too. I've just sent off an enquiry to the oz distributor (who is in my own city) to see if they still have a v5.1 available.
    Thanks again!

  7. #17
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    Quote Originally Posted by Skullmeat View Post
    Unfortunately, the chassis and psu I had marked for purchase for this build has been sold, and due to my limited budget, I cannot afford $200+ blackplane and chassis. Even If I got a bare backplane, I do not have a psu, (could possibly get an ATX, but that's still money I don't have) and still, where am I gonna put that big old cpu board without a chassis? I am going to have to shelve this project, unless I can find something that is affordable.
    I don't know the price differences, but do you really need a J-11? I would think that an F-11 is a lot cheaper (I sold one last week on eBay for $58, with the FP chip installed). And maybe an LSI-11 is even less? What SW do you want to run that requires a J-11 or big memory?
    When it comes to running the Real Hardware, I get all my satisfaction from the low-end CPUs (LSI-11 and T11). If I built a physical system that would run (for example) RSX, what would I do with it, that I can't do better via emulation? With a low-end system, I can play with PDP assembly code, make lights blink, build Qbus interface boards, run Forth, etc.
    And with a T11, you can build a functioning microcomputer from scratch which executes the PDP-11/03 instruction set (I did it a few years ago, if you're interested in techie details). It runs from a 5V wall-wart, and doesn't need any fans.
    An LSI-11 CPU board, plus an MXV11 board, gives you a minimal system with 16KW of RAM, two serial ports, and a pair of EPROM sockets. You could hand-wire a "backplane", and only a minimal fan is needed.

    Pete

  8. #18
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    I think the only thing you need is a CPU board and a backplane. Everything else can be built by yourself. However I did find it very difficult to find a reasonably priced backplane. I've never seen any useful backplane for less then approx 200USD.
    For more information about my projects see https://www.5volts.ch

  9. #19
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    Quote Originally Posted by saipan59 View Post
    I don't know the price differences, but do you really need a J-11? I would think that an F-11 is a lot cheaper (I sold one last week on eBay for $58, with the FP chip installed). And maybe an LSI-11 is even less? What SW do you want to run that requires a J-11 or big memory?
    If you want the option of running 2.11BSD you need a J-11 CPU (at least in the Q-Bus world).

    The current cost different between a J-11 CPU board vs. an LSI-11 or F-11 CPU board isn't that significant relative to the overall cost of putting a system together.

    Say you can get an M7554 KDJ11-D with two SLUs and 1.5MB of memory on board for $100, how much would it cost to get an M8189 KDF11-B with two SLUs on board, and then also add a memory board? Of if you go with an M8186 KDF11-A you also need to add an SLU board, and optionally an M8012 BDV11 if you want boot ROMs.

  10. #20
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    Quote Originally Posted by cbscpe View Post
    I think the only thing you need is a CPU board and a backplane. Everything else can be built by yourself. However I did find it very difficult to find a reasonably priced backplane. I've never seen any useful backplane for less then approx 200USD.
    The original poster should have bought that DYS50D for less than $90 shipping as soon as it was noticed instead of giving other people a chance to find it and snatch it up. Even if the chassis was empty of everything except the H7861 power supply and H9276 Q22/CD backplane you're not likely to find a better deal unless you find someone getting rid of something locally and don't have to pay for shipping.

    At the $90 price delivered for that DYS50D I was tempted myself, but I already have too much Q-Bus stuff, and it would have been rude to buy it out from under the original poster.

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