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Thread: FreHD update 18/10/13 - Self boot with menu for Model III/4 - READY FOR RELEASE

  1. #1
    Join Date
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    Default FreHD update 18/10/13 - Self boot with menu for Model III/4 - READY FOR RELEASE

    Hi everyone, see video below with the FreHD self boot and menu system in action:



    I'm getting ready to release this product, at the moment replacement EPROMs have been developed for the Model III, 4NGA (with early rom set) and 4GA/4D (requires some soldering skills).

    For those with the ability to burn an EPROM, you can email me now for upgrade software.

    For those who need to buy the burned EPROM they will be $25 + normal shipping costs (generally $8 max to anywhere in the world).

    If interested to be put on a waiting list for when this product is ready to release, send me an email.

    NOTES:

    1. The computer needs to be opened to install the Eprom. For those unfamiliar with opening their computer and changing chips, this might present some anxiety.

    2. The Eprom you need depends on what Rom set you have in your computer - so I need to ask some questions before sending out the correct Eprom, and at this stage, not all machines are covered (M4NGA late Rom set being one).

    3. Because of special requirements for partition 1 on each image (must be 203 cyl/1 head) new images may be needed - I'll be working on new standard images soon.

    4. When the Eprom change you lose the ability to write 500 baud tapes. You can still load 500 and 1500 baud tapes.

    Discuss.

    Ian.
    *There is never a charge for Tech Support even if you don't purchase from me - We are Enthusiasts Helping Other Enthusiast and that is just the way it is

  2. #2

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    Quote Originally Posted by TRS-Ian View Post
    Discuss.
    Looks great! I'll certainly be putting my name down for a new EPROM & images soon.

    From the sounds of it, the change is easily reversible should that be needed (just swapping back the original EPROM), is this correct? Also, it's good to see that CP/M 2.2 is already working with this setup, do you plan to create CP/M 3.x images for it as well? If not, I assume that I'll still be able to boot CP/M 3 from a floppy like I currently do.

  3. #3

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    Regarding the loss of writing 500 baud tapes: How about an option to switch between original and autobooting ROMs, for those who would like that? Since I spend most of my days designing PCBs, the first thing that comes to mind is a little daughterboard that plugs in to the old ROM socket, and then either holds two ROMs or one ROM with the most significant address bit used as a bank switch. A toggle switch could be mounted somewhere to select between the ROMs. Some might prefer to take the approach of just lifting the most significant address pin of the EPROM rather than using a custom board, but that's not over-designed enough for my preferences.

    My Model 4 has the RS-232 connector facing towards the rear. Does that make it a gate array version? I am quite comfortable soldering anything with exposed contacts (that is, I'm not comfortable dealing with BGAs yet, but anything else is fine). Can you explain what sorts of modifications are needed? Is it something that could be turned into a plug-and-play no-soldering modification with some sort of adapter board? If an adapter boards would be helpful, I could design one if you or Fred doesn't want to.

    I'm interested in trying this out on my Model 4 and/or Model 4P. Maybe I'll be able to contribute something back to the community, too?

  4. #4
    Join Date
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    Yep you got a Gate array there. Oh you have never removed/reballed a BGA chip! oh what fun....NOT! Pain in the rumplestiskin if you ask me.

    The Gate Array mod has to do with running 3 wires from the EPROM to points on the board. 1 Being ground the other 2 are going to via's.
    as far as I can tell.
    *FrankG*

  5. #5

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    Quote Originally Posted by NF6X View Post
    My Model 4 has the RS-232 connector facing towards the rear. Does that make it a gate array version?
    Yes, a RS-232 connector that faces to the rear is the definitive externally sign of a gate array Model 4.

  6. #6

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    I emailed Ian to learn more about this, and the wires are needed to adapt a 2764 EPROM (28 pins) into the original mask programmed ROM socket (24 pin, different pinout). I am highly allergic to blue wires (even though the computer already has a bunch of them from the factory), so I think I will design a little board that plugs in to the old ROM socket, accepts both the old ROM and a new 2764 EPROM, and allows either to be selected with a jumper or remote switch. I'm still thinking about its deign requirements, but I think I might include a little bit of logic on it so that the actual chip select signal doesn't need to be run out to a remote switch and back, in order to avoid timing and signal integrity problems. Maybe it would work just fine with a simple switch, but I'm envisioning that there could be multiple feet of wire between a switch and the board.

    Some (all?) of the other computer versions apparently will accept standard 27xx EPROMs in their ROM sockets.

    I had a silly idea that I might implement: Mount the FreHD inside a floppy drive chassis (preferably a bad one, rather than gutting a good drive) with the SDA card poking out the floppy slot. Replace the red and green LEDs with a bi-color LED mounted in place of the old floppy drive activity LED. Install a microswitch to be actuated by the floppy door, so that closing the door selects the new FreHD EPROM and opening it selects the original ROM, or vice versa. Install it in place of the upper floppy drive to create a single floppy, internal HD computer that looks nearly original at first glance.

  7. #7
    Join Date
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    If it's the same as most other 24pin masked roms. (Coco, C64, etc.) then take a look at this.

    http://store.go4retro.com/2364-adapter/

    Later,
    dabone

  8. #8
    Join Date
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    Ok, I just ordered my model B kit for the frehd kit, and was wondering is anyone had done a bom for mouser?
    (newark has a 20.00 freight charge per order??? wtf..)

    Thanks,
    later,
    dabone

  9. #9

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    If I remember correctly, it is an MCM68C364.

  10. #10

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    Here's a BOM that covers Jameco and Digikey.

    www.geneb.org/FreHD parts list.ods

    I can add a Mouser column if someone wants to supply the part numbers.

    g.
    Proud owner of 80-0007
    http://www.f15sim.com - The only one of its kind.

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