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Thread: Using embedded micros for emulation/replacement of various I/O of classic computers

  1. #11
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    Quote Originally Posted by Al Kossow View Post
    I would think after 20 years of people complaining that DEC OSs are encumbered, someone would just write a work-alike for RT-11, RSX or RSTS.
    It's just human nature. Writing a new operating system is work and complaining is a hobby .

  2. #12
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    Quote Originally Posted by Al Kossow View Post
    I don't understand why there is almost no new software being written for older processors, after going to all of the trouble of getting them running again.

    With all of the people hacking on PDP-11s, there are no new operating systems for it.
    I would think after 20 years of people complaining that DEC OSs are encumbered, someone would just write a work-alike for RT-11, RSX or RSTS.
    A new OS is no big deal, but getting absolute API compatibility with old applications is, particularly when said applications either lack source code or have undocumented "features". Consider the case with NT emulating MSDOS or Linux WINE emulating Windows. It's never 100%, In fact, software ISA emulators are far more successful at this--they simply emulate whatever hardware interface is needed and host the native OS.

    Of course, you can write your own applications and use whatever API you like. Unix did this--and early Unix was no great shucks--it took years before a usable set of applications made it fit for general use.

  3. #13
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    Quote Originally Posted by Al Kossow View Post
    With all of the people hacking on PDP-11s, there are no new operating systems for it..
    Wouldn't Alan Cox' Fuzix qualify? There is at least a stub for a cpu-pdp11 in git.
    https://github.com/EtchedPixels/FUZIX

    But it does seem like most people running old iron seem to want to relive the glory days and run old software instead of doing something new.

    A FreeRTOS port might be interesting, and should fit easily enough, since it can run on the AVR platform, which is essentially the same horsepower as at least a portion of the range of the 11.
    Last edited by lowen; May 9th, 2019 at 10:30 AM.
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    The libraries build but it broke gcc and gnu binutils too much to proceed further. gcc appears to have been fixed but not yet binutils. In many ways it is not a good fit for the PDP anyway. One of the core assumptions Fuzix makes right now is that storage controllers are dumb. For home micros and retrobrew stuff this works well. None of them are capable of doing any meaningful work while doing hard disk I/O.

    For most minis it's a bit of different story.

  5. #15

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    I am now pursuing this for the HP 98x5 series of computers after I was not able to get my 98035A clock interface to an operational state after the battery had leaked on it years before I got it. The problem with getting the 98035A working is the the clock chip used by HP appears to be repackaged TI watch chip with no datasheet available. It seems to have been damaged and will no longer drive the 32768 Hz crystal oscillator into oscillation, nor does it respond to the nanoprocessor "pressing" the buttons.

    So rather than run through a series of old 98035A interfaces that may have suffered the same fate, I'm looking at using a Diligent Cora Z7 Zynq development board mounted on an interface board to the 98x5 I/O bus. The Arm processor can run Linux and theoretically emulate any of the processors, as well as new ones, with the FGPA handling the low level details of acting as a peripheral or even a bus snooper.

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