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Thread: P112 SBC or ZETA SBC V2

  1. #1

    Default P112 SBC or ZETA SBC V2

    Are ether/both of these still available? How do they compare to each other?

  2. #2
    Join Date
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    P112: Z182 with up to 1MB of RAM, floppy controller, serial and parallel. With the right Z182 you can run 33 MHZ or even a bit faster. Has surface mount parts. Not currently available.

    Zeta: Z80 based, has floppy, etc. All through-hole construction. Can still be sourced.

    Both boards can be fabbed from gerbers, but the P112 is four-layer. I've built a P112 and have it runable, and have a Zeta board to populate, but haven't finished it.
    --
    Thus spake Tandy Xenix System III version 3.2: "Bughlt: Sckmud Shut her down Scotty, she's sucking mud again!"

  3. #3

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    Where is the ROM image for the Zeta 2 ?

    I saw a link going to this:
    https://github.com/wwarthen/RomWBW

    and it says something about prebuilt .ROM images, but I don't see them...

    ALSO - is there a way to get a second serial port on the Zeta?

    ALSO ALSO - has anyone made a CP/M 3 for it?
    Last edited by alank2; February 20th, 2019 at 07:06 PM.

  4. #4
    Join Date
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    Silicon Forest, Oregon, USA
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    Quote Originally Posted by alank2 View Post
    Where is the ROM image for the Zeta 2 ?

    I saw a link going to this:
    https://github.com/wwarthen/RomWBW

    and it says something about prebuilt .ROM images, but I don't see them...

    ALSO - is there a way to get a second serial port on the Zeta?

    ALSO ALSO - has anyone made a CP/M 3 for it?
    ROM for Zeta SBC V2 - The instructions and pre-built packages are posted at Retro Brew Computing. Of course you can compile your own ROM image from Wayne's GitHub repo...

    Second serial port:
    - The ParPortProp board has a 3-wire (RX/TX/GND) RS-232 interface connected to the Propeller chip. I don't think it was ever enabled in the firmware though. Something to ask Wayne about.
    - Theoretically you can solder another 8250/16450/16550 UART on top of the existing one, add the chip select logic (e.g use A2 to select between two UARTs), and (if needed) MAX232 or similar level shifter IC.

    CP/M 3 - There were attempts to enable CP/M 3 on N8VEM (and Zeta SBC, but not Zeta SBC V2). Also there is CP/M 3 installation from S100Computers folks. Zeta SBC V2 has a very flexible memory paging, so it shouldn't be a problem with enabling CP/M 3 on it.
    - https://retrobrewcomputers.org/n8vem...15/install.txt
    - https://www.retrobrewcomputers.org/d...eos:zsos:start

  5. #5

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    Thanks Sergey!! I appreciate it! I found a zeta2 pcb on eBay along with an IC kit with many of the IC's in one kit. I saw a YouTube video to support a SDCARD without the ParPortProp (I've got a terminal) - do you have any of those pcb's?

  6. #6
    Join Date
    Jul 2010
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    Silicon Forest, Oregon, USA
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    Quote Originally Posted by alank2 View Post
    Thanks Sergey!! I appreciate it! I found a zeta2 pcb on eBay along with an IC kit with many of the IC's in one kit. I saw a YouTube video to support a SDCARD without the ParPortProp (I've got a terminal) - do you have any of those pcb's?
    I think you're talking about PPISD. I don't have any of these PCBs. But please check the board inventory at Retro Brew Computers.

    Zeta SBC V2 must be popular if Chinese guys sell a kit for it... BTW looking at the picture it seems that they've got a wrong FDC. Z80 CPU is a recycled/relabeled one too.

  7. #7

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    Hi Sergey,

    It is a kit of just the IC's for $24 shipped - not sure if it was a good deal or not.

    https://www.ebay.com/itm/Z80-Zeta-SB...t/113085366565

    It looks like it says it has a D765AC-2 - Will this work in place of "WD37C65, FDC37C65, GM82C765"

    I figured I could source parts for whatever doesn't work. Do you think the FDC is wrong still?

    Thanks!

    Alan

  8. #8
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    Jul 2014
    Location
    New Hampshire, USA
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    The Zeta is a very slick design and well supported.

    As Sergey pointed out the Z80 in that kit is counterfeit, and the FDC provided is useless for the Zeta.

    The Z80's from China are all blacktopped/reprinted in my experience. Many are older parts that will barely handle 4mhz. While you occasionally need to deal with the Chinese secondary market for older parts, Z80's are still readily available. Do yourself a favor and order from Mouser or Digikey and get a legitimate 20mhz Z80 CPU and CTC.

    The ParaPortProp is also pretty slick, you might reconsider.

    I can't recall where I picked up a WD37C65, might have been UTSOURCE.NET

    - Gary

  9. #9
    Join Date
    Jul 2010
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    Silicon Forest, Oregon, USA
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    Hi Alan,

    It is a pretty good deal. A set of new ICs at Mouser is going to cost about twice as much. Just don't expect these ICs to be brand new, it is quite possible that most of them will be "pulls".
    D765AC-2 is the original NEC µPD765A FDC, without data separator and without additional IBM PC specific logic, so no, it will not work instead of 37C65.

    Thanks,
    Sergey

  10. #10

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    Thanks guys. I've got one or two Z80 DIP packages kicking around that are from Mouser/Digikey, so I can try them and see how they go. The FDC IC is a bit annoying as that is one of the IC's I can't source from DK/Mouser. I'll send him a message and ask what he is sending...

    The ParPortProp does look very cool, but one thing I'm trying to do is keep the parallel port open to play around with interfacing it to things for fun. I'm planning on trying to use the GoTek I've been playing with as a floppy drive for it and see how that goes.

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