Kaypro dead.. how to use the monitor? - CP/M

This is a discussion on Kaypro dead.. how to use the monitor? - CP/M ; I have a dead (highly unreliable) Kaypro II. I asked about it here a few months ago but now it is really kaput. So, I'm thinking to use the case and monitor in some way. From looking at the Kaypro ...

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  1. Kaypro dead.. how to use the monitor?

    I have a dead (highly unreliable) Kaypro II. I asked about it here a
    few months ago but now it is really kaput. So, I'm thinking to use the
    case and monitor in some way. From looking at the Kaypro technical
    manual I know which pins of which jumper control the horizontal and
    vertical sync. So, here are my two questions:

    1. What do I need to do to be able to feed a composite video signal
    into the monitor?
    2. How could one control the TTL video with a microcontroller?

    If I can feed a composite video signal in I might put an Apple IIgs
    motherboard into the case. If it is too hard to get composite working
    (I'm an electronics newbie) then it would be fun to control the video
    with some sort of PIC, perhaps to make a sinple Pong-like game (yes, I
    know others have done this already).

    Does anyone have any insights? All replies much appreciated.

    Ron


  2. Re: Kaypro dead.. how to use the monitor?

    Ron Kneusel wrote:
    > I have a dead (highly unreliable) Kaypro II. I asked about it here a
    > few months ago but now it is really kaput. So, I'm thinking to use the
    > case and monitor in some way.

    [snip]
    > Does anyone have any insights? All replies much appreciated.


    How about this?
    http://www.ccs.neu.edu/home/bchafy/kp/kaypro.html


    --
    David Griffith
    dgriffi@cs.csbuak.edu <-- Switch the 'b' and 'u'

  3. Re: Kaypro dead.. how to use the monitor?

    Dave Griffith wrote:
    >
    > How about this?
    > http://www.ccs.neu.edu/home/bchafy/kp/kaypro.html


    Yes, this is what I was thinking about when I commented that others
    have done this. However, he doesn't give any details on how it was set
    up. I guess I'm looking for suggestions on how to go from composite
    signal to separate horiz./vertical syncs with video. OR, how to
    control those lines with a microcontroller to generate my own video.

    Thanks for the reply!

    Ron


  4. Re: Kaypro dead.. how to use the monitor?


    "Ron Kneusel" wrote in message
    news:1151870690.273753.130680@a14g2000cwb.googlegr oups.com...
    >I have a dead (highly unreliable) Kaypro II. I asked about it
    > here a few months ago but now it is really kaput. So, I'm
    > thinking to use the case and monitor in some way. From
    > looking at the Kaypro technical manual I know which pins of
    > which jumper control the horizontal and vertical sync. So,
    > here are my two questions:
    >
    > 1. What do I need to do to be able to feed a composite video
    > signal into the monitor?
    > 2. How could one control the TTL video with a microcontroller?
    >
    > If I can feed a composite video signal in I might put an
    > Apple IIgs motherboard into the case. If it is too hard to
    > get composite working (I'm an electronics newbie) then it
    > would be fun to control the video with some sort of PIC,
    > perhaps to make a sinple Pong-like game (yes, I know others
    > have done this already).
    >
    > Does anyone have any insights? All replies much appreciated.
    >
    > Ron


    The synch information in a composite video signal is usually
    carried in the negative tips of the wave form. Capturing it
    involves "clamping" the tips (with a capacitor and diode) to
    remove any A.C. variations, and "slicing" the pulses with a
    comparator (which may be just an un-biased transistor fed from
    a resistor to its base).

    The horizontal and vertical portions are separated by a
    "one-shot" edge-triggered pulse timer, with some "AND" gates,
    to distinguish short pulses from long. On the other hand, it
    may be enough to deliver the combined synch signal to both
    the monitor's synch inputs, and see if the monitor can
    separate them. In either case, the polarity(s) of the signals
    may be important (mostly high vs. mostly low).

    I think some CGA cards could be set for composite video out,
    but still generated separate synch and video on the digital
    interface.

    To generate the pulses required rather precise and very
    repeatable timing. It is therefore usually created with
    hardware, consisting of a crystal based clock and a series
    of counters (plus a few gates). The schematics for the
    Kaypro give one such design, of course :-).

    You need to generate around 15,750 horizontal lines per
    second, with 2 vertical pulses every 525 lines. For normal
    interlace, one usually starts with at least 31,500 pulses
    per second, and separate dividers (/2 and /525) to get the
    interlace phasing correct. The Kaypro monitor will probably
    look better with non-interlaced timing, say, 1 vertical
    pulse every 264 horizontal lines. It is sometimes important
    to lock the synch signals to the local power line frequency,
    to hide any "beating" with the vertical rate.

    A microprocessor with a hardware timer for the horizontal
    pulses and an interrupt-driven routine to set the vertical
    pulses might be easy enough, but you would still be faced
    with generating the video pulses in the proper
    synchronization.

    A pong type game would generally use several more hardware
    timers for the horizontal positions of the paddles and ball,
    but might get by with a per-line interrupt for all the
    vertical timing. In that case, some external gates for
    mixing the horizontal and vertical info might still be needed.

    The Timex-Sinclare ZX80/81 had a hardware+software scheme
    that accomplished all this by force-feeding the CPU
    hardware-controlled op-codes during the video display phase.

    P.S. What is this "unreliability" that leaves you thinking
    that the video is still good? Maybe you have a problem
    with the +5V supply that should be fixed instead?



  5. Re: Kaypro dead.. how to use the monitor?

    Fred J. Scipione wrote:
    [snip: good stuff about timing of pulses]
    This seems to be very close to the sort of thing I was looking at
    recently using a simple PIC to generate video signals for composite
    inputs. But, am I correct in thinking for this case that the
    horizontal sync needs to be set high (1V?) at the same point where, in
    a composite signal, it would be set? I'm thinking about the project
    described here:

    http://www.rickard.gunee.com/project.../pic/howto.php

    It seems to me that this sort of setup would be perhaps even easier
    with the Kaypro monitor? The "video" line, I assume, is varies in
    voltage to generate the intensity for that scan line?

    > P.S. What is this "unreliability" that leaves you thinking
    > that the video is still good? Maybe you have a problem
    > with the +5V supply that should be fixed instead?


    When powered up the disk drives both spin continuously and the machine
    won't boot. The boot message does come up, however. I've already
    played with the cables and re-seated all the chips. It went away on
    its own for a time but now seems permanently stuck in this state.

    Ron


  6. Re: Kaypro dead.. how to use the monitor?

    Dave Griffith wrote:
    >> How about this? http://www.ccs.neu.edu/home/bchafy/kp/kaypro.html


    Ron Kneusel wrote:
    > Yes, this is what I was thinking about when I commented that others
    > have done this. However, he doesn't give any details on how it was
    > set up.


    Cute! I've done similar things with old Heathkit H89 cases. They worked
    out surprisingly well.

    I converted one into a Mac, with a Mac SE motherboard replacing the
    Heath boards. The existing power supply and video monitor worked fine
    as-is. The monitor had enough adjustment range to accomodate the Mac's
    19.2 KHz scan rate with no problems. I named it "Mac Heath" (the full
    name of the killer in the Three Penny Opera song "Mac the Knife :-)

    I converted another into a PC, with the motherboard standing vertically
    at the back of case, and all the plug-in cards facing forward (just like
    the stock Heath setup). Again, the monitor worked with EGA cards of the
    time. The power supply was marginal, so I had to add a little 5v
    switcher.

    Finally, I put in *both* a Mac motherboard (which provided the screen,
    keyboard, and hard drive interace), and an H-1000 board (which had both
    Z80 and 8086 CPUs, and 1 meg of RAM). This one system ran CP/M-80,
    CP/M-86, PC-DOS, and Mac software!
    --
    Ring the bells that still can ring
    Forget the perfect offering
    There is a crack in everything
    That's how the light gets in -- Leonard Cohen
    --
    Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

  7. Re: Kaypro dead.. how to use the monitor?


    "Ron Kneusel" wrote in message
    news:1151957098.061418.282790@h44g2000cwa.googlegr oups.com...
    > Fred J. Scipione wrote:
    > [snip: good stuff about timing of pulses]
    > This seems to be very close to the sort of thing I was looking at
    > recently using a simple PIC to generate video signals for composite
    > inputs. But, am I correct in thinking for this case that the
    > horizontal sync needs to be set high (1V?) at the same point where, in
    > a composite signal, it would be set? I'm thinking about the project
    > described here:
    >
    > http://www.rickard.gunee.com/project.../pic/howto.php
    >
    > It seems to me that this sort of setup would be perhaps even easier
    > with the Kaypro monitor? The "video" line, I assume, is varied in
    > voltage to generate the intensity for that scan line?


    Yes, if you follow the examples in the project page, you would run
    the PIC bits for synch and video directly to the Kaypro monitor,
    instead combining them with resistors. You would need to avoid
    the 'gray' video state, or use an 'OR' gate, to keep the video
    out of the synch bit. Since the Kaypro's 'brightness' knob works
    by dividing the TTL video voltage, we know that the monitor's video
    input will respond to analogue video voltages, not just TTL. In
    fact, you may need to run any video to the brightness pot first,
    instead of directly to the monitor, to limit the screen brightness.

    The page mentions the LM1881 synch separator chip, which you might
    use to create (separated?) TTL horizontal and vertical signals
    from any composite video source. It will provide the clamping,
    one-shot timing, and logic gates I indicated before.



  8. Re: Kaypro dead.. how to use the monitor?

    Fred J. Scipione wrote:
    > Yes, if you follow the examples in the project page, you would run
    > the PIC bits for synch and video directly to the Kaypro monitor,
    > instead combining them with resistors.

    [snip]
    > The page mentions the LM1881 synch separator chip [snip]


    Thanks for the pointers! I'll look into it.

    Ron


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