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Thread: M847 extended edition > Bootloader in PDP style !

  1. #11

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    Quote Originally Posted by Roland Huisman View Post
    Very nice, I've seen your repair story on that machine. Unfortunately I don't have a PDP8/a.
    I like the keyboard on the front. And I wonder if a bootloader like I built would work also in an PDP8/a.
    The /e /f and /m are all the same. As far as I know the original 8/m did not have toggle switches.
    But only a few of these are known. The most are having the same front panel as the /f.

    I think this board should also work in that original /m because that machine has the SW switch as well...
    This bootloader should work just fine in a PDP-8A as well. It also have the SW-signal connected to the boot-flipflop controlled by the boot button an the programmer console and the boot switch on the limited function panel. As long as the boot feature on the KM8A board is disabled...

    When I looked at the schematic I realized what this is, it's a half front panel emulator! If the examine and status functionality would be added to this board it will become a most powerful tool for all the PDP-8's with omnibus! I know that this would take some effort, quite some circuitry must be added to get there.

    The thing is that not all PDP-8A's where sold with the programmers console, which make them almost impossible to debug!

  2. #12

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    Quote Originally Posted by anders_bzn View Post
    This bootloader should work just fine in a PDP-8A as well. It also have the SW-signal
    connected to the boot-flipflop controlled by the boot button an the programmer console and the boot switch on
    the limited function panel. As long as the boot feature on the KM8A board is disabled...
    Okay, good to know! Do the same bootloaders / tests apply as well?

    Quote Originally Posted by anders_bzn View Post
    When I looked at the schematic I realized what this is, it's a half front panel emulator!
    Yes, it is a automatic front panel indeed. Nothing more nothing less...
    I just took out al the lamp / LED logic because that is in the /e /f /m front panels.

    Quote Originally Posted by anders_bzn View Post
    If the examine and status functionality would be added to this board it will become a most
    powerful tool for all the PDP-8's with omnibus! I know that this would take some effort, quite some circuitry must be added to get there.
    Sounds good. I will think about that option. It should't be too difficult. And how did you like to see this?
    LED's on the PCB? Or output the data trough a serial port to a monitor terminal?

    Another option is to leave the bootloader for what it is now and make an LED/switch PCB in PDP8/i style
    for the Omnibus machines. So you don't have to choose between State, status, AC, MD, MQ and Bus.
    Just show all of it... This keeps the bootloader cheap for those who already have a front panel machine.

    I would love to hear idea's and also bootload / toggle in programs to be added.
    My idea is to reserve the first 15 options for real bootloaders and the higher range
    is free to put in the test programs which are not used very often...

    Regards, Roland
    Last edited by Roland Huisman; October 27th, 2018 at 04:22 AM.
    WTB: RX8E / M8357 and Case for Altair 8800

  3. #13

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    Quote Originally Posted by Roland Huisman View Post
    Okay, good to know! Do the same bootloaders / tests apply as well?
    Yes, basically. There are a set of MAINDEC's for the PDP-8A CPU/option boards. Simple toggle in programs and bootloaders are the same.

    Quote Originally Posted by Roland Huisman View Post
    Sounds good. I will think about that option. It should't be too difficult. And how did you like to see this?
    LED's on the PCB? Or output the data trough a serial port to a monitor terminal?
    I have got two PDP-8A systems, none of them came with the programmers console. Luckily I found a programmers console (costed a kidney) on Ebay and I have borrowed one more. I think the board should be kept as simple as possible and something should access it over a serial port like the PDP-11 GUI: http://retrocmp.com/tools/pdp11gui

    Quote Originally Posted by Roland Huisman View Post
    Another option is to leave the bootloader for what it is now and make an LED PCB in PDP8/i style
    for the Omnibus machines. So you don't have to choose between State, status, AC, MD, MQ and Bus.
    Just show all of it... This keeps the bootloader cheap for those who already have a front panel machine.
    Maybe one PCB with optional mounts of components to turn it into a frontpanel emulator.

    Quote Originally Posted by Roland Huisman View Post
    I would love to hear idea's and also bootload / toggle in programs to be added.
    My idea is to reserve the first 15 options for real bootloaders and the higher range
    is free to put in the test programs which are not used very often...
    Yes, small program for just testing a loop. A console test putting out characters one the serial port and one with local echo.

  4. #14

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    Funny,

    My first intention was to daisychain my bootloader with an M865x.
    When you toggle the SW switch, the bootloader switches the serial line off the
    M865x and then takes over the communication with the terminal and pops up a bootmenu.
    Then you should be able to run whatever you want from a PC or terminal side.
    Load the pre-programmed bootloaders or type in your own bootloaders and
    store them in the EEPROM of the board...

    One of the disadvantages is that you have to set the bootloader to the same speed as
    the M865x (or vice versa) But you don't have to use it in that way... You can always use the SW
    switch and see which program would be loaded in the address LEDs.

    But then I thought that it might be a bit of an overkill... Back to the basics and just
    make that bootloader first. From there I can see what the demand is...
    Every option costs hours of work. But can save a lot of hours too in the future...

    And now I really like what you showed there with that PDP11 GUI !
    I've no idea if that program is easy to rebuilt to a 12 bit system.
    I would like to know what data you would need exactly on the serial bus...

    One thing which might be a problem is that you can not read all the status LEDs when the machine
    is running at full speed. (Well it could be, but then you need far more sophisticated electronics...)
    But single stepping, or reading after a break of halt would be no big problem...
    And a quick read about the PDP11 GUI, the PDP11 serial programming protocol must work in the same way...

    I have a PDP11/23, can I use that PDP11 GUI on that to see how it works? And I wonder, who wrote
    that GUI? Maybe he can speak up here and throw in his thoughts and experience?

    I want to prevent an uncontrolled never ending project, but I do see a lot of potential here...
    Last edited by Roland Huisman; October 27th, 2018 at 11:34 AM.
    WTB: RX8E / M8357 and Case for Altair 8800

  5. #15

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    Haven't used the PDP-11 GUI, but PDP-11 has something call ASCII console that the PDP-11 GUI uses. My 11-machines will come after the 8's are done...

    I guess this might help: https://github.com/j-hoppe

    A 11/23 should work with the GUI

  6. #16

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    Quote Originally Posted by anders_bzn View Post
    Haven't used the PDP-11 GUI, but PDP-11 has something call ASCII console that the
    PDP-11 GUI uses. I guess this might help: https://github.com/j-hoppe A 11/23 should work with the GUI
    Well I will see how that works. First my RK05 will get it's attention from me...

    In the meanwhile I wonder how big the demand is for the bootloader. Two of my prototype
    boards are given away now. I've got one left. But I don't hear many people which are interested in the board.
    When the project is done it's free for everyone who likes if. You can order your own PCB's from the gerber files
    or do a group buy...

    I've made an upgrade in some details in the current bootloader. I've put an MAX232A on it together
    with a BERG and DSUB-9 connector for easy connecting to a PC for flashing the program trough
    the Arduino IDE. This is because I don't want SMD on the board. In this way it will be easy for
    everyone to built the board in the future. No special or expensive tools are needed then.

    The idea of the BERG connector is that they are flat. A disadvantage of the DSUB is the
    metal rim and it's thicker then a normal omnibus card space... So there is a risk for short circuits then...
    It just adds an option, but personally I prefer the BERG connector. Just use a cable from the M865x
    to flash a new firmware. Only needed when you want to update in it. Simple as that

    Further, I've added a push button for the SW function as well and I've added an EEPROM
    which is not necessary yet. Just for future maindec's to load...

    For now the RIM-loader, BIN-loader, all toggle-in tests and all M847 bootstraps are in the card now.
    So this really adds a boot menu for multiple bootable devices to your system!

    This is a render of the next PCB...
    M847 extended edition V1.1.jpg

    I will make a new demo of how it works now. I'm searching for a good place to share my board
    designs and software. (H851, M993, omnibus extender, bootloader PCB, software for bootloader...)
    Any idea's? Github? Is Github also suitable for PCB's?

    Regards, Roland
    Last edited by Roland Huisman; October 30th, 2018 at 02:56 PM.
    WTB: RX8E / M8357 and Case for Altair 8800

  7. #17
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    Github is a great place for sharing anything. You could also share your PCB designs at Oshpark, but using Github is vendor neutral. Take a look at Joerg Hoppe's profile that Anders referenced above for some ideas about making access easy.

  8. #18
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    Quote Originally Posted by jackrubin View Post
    Github is a great place for sharing anything. You could also share your PCB designs at Oshpark, but using Github is vendor neutral. Take a look at Joerg Hoppe's profile that Anders referenced above for some ideas about making access easy.
    Github is where I share the complete design for my RX02_EMULATOR design. Arduino files, documentation, pictures, BOM, gerber files for PCB.

    Boards are shared on OSHPARK as well.

    See: https://github.com/AK6DN/rx02_emulator as an example.

    Don

  9. #19

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    Great, then I will make an account there...

    Don, that RX01 / RX02 emulator is a nice project btw!
    WTB: RX8E / M8357 and Case for Altair 8800

  10. #20
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    M847 extended - neat, nice and easy to operate. I like that. Bravo!
    Torfinn

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