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Thread: Exidy Sorcerer error

  1. Default

    I helped Tempest (who posted upthread) repair his Sorcerer II with the same symptom, no DRAM. It was a bad cap on the 12V bus, as others have posted. After locating and replacing it his machine has run well for years, although he does not have the S100 unit.

    This thread shows our repair progress plus other activities:
    http://www.vcfed.org/forum/showthrea...r-II-Questions
    Last edited by ClausB; January 31st, 2020 at 02:37 AM.

  2. Default

    Quote Originally Posted by JonB View Post
    Responding to a query posted on StarDot:

    My Sorcerer had a short circuit on the 12v rail which was caused by a tantalum capacitor. The way I resolved it was to desolder one leg of each capacitor until the short circuit went away, then replace any tants that were faulty. It's easy enough to do this, even working from the component side of the board (especially if you have a decent soldering iron).
    This is good advice.

    Also, if you want to fix the video tearing in your photo below, look here:
    http://www.vcfed.org/forum/showthrea...500#post421500

    ExTears.jpg
    Last edited by ClausB; January 31st, 2020 at 04:29 AM.

  3. #53
    Join Date
    May 2018
    Location
    Melbourne, Australia
    Posts
    221

    Default

    Quote Originally Posted by ClausB View Post
    Also, if you want to fix the video tearing in your photo below, look here:
    http://www.vcfed.org/forum/showthrea...500#post421500
    I'm not dismissing your work in figuring out why it happens or suggesting that it was intentional on the part of Exidy.
    However presumably in a museum you want to give visitors the opportunity to experience the system operating in an authentic way though.
    I would argue that those artifacts in the display are as much a part of the sensory experience of using a Sorcerer just as much as the sound and feel of the keyboard, the smell of the transformer heating up the case etc.
    The artifacts are actually useful during cassette loading as shows you that data is being read, and in the penultimate section of a Scott Adams adventure you can literally see the machine working harder which adds to the anticipation by letting you know you are very close to completing the game.

  4. Default

    After the mod you still get the dark speckles during screen access, just not the horizontal jitter. But, point taken.

  5. #55

    Default

    Ok, we finally had time to take a good look at our Exidy.

    It started with a missing +12V rail, caused by lm340t12 which was broken. After replacing this voltage regulator, the new one got hot very quick, showing a full short on the 12v rail. We found multiple tantalums in short. Replaced 28 of them (4x 100uF, 28x 100nF) and behold!



    It starts up Basic. This photo was shot with only 16K memory, eventually we put 32K in and it works. The only thing not working (yet), is booting CP/M via de S100. The interface works, the drives start to read but I think it's a read fault. So, we're going to clean the heads to see if we can boot the hard sectored disks.
    Founder of the HomeComputerMuseum in the Netherlands. Fully interactive computermuseum dedicated to the home computer.

  6. #56
    Join Date
    May 2018
    Location
    Melbourne, Australia
    Posts
    221

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    That's great! I've been watching your socials and wondering if the Sorcerer was moving up the queue

  7. #57

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    and we even got it on video!

    Founder of the HomeComputerMuseum in the Netherlands. Fully interactive computermuseum dedicated to the home computer.

  8. Default

    Congrats for getting it working. Nice video too. One correction: in the video you say twice that all the graphics characters are in ROM. That is false. Half ( 128 ) of the characters are in RAM, so games can define many custom special symbols, which is why they look so good.

  9. #59

    Default

    Actually you both are half-right, half-wrong.

    Characters 0-127 are in the character rom and cannot be changed.
    Characters 128-191 are called Standard Graphics and are defined in ROM, and copied to RAM whenever the screen is cleared. You can do it anytime by pressing the CLEAR key.
    Characters 192-255 are called Extended Graphics and are entirely in RAM.

    So, 128-255 can be redefined to whatever you want in the 8x8 matrix. But pressing Clear will wipe away your changes to the Standard Graphics.

    Many of the modified monitor roms will remove the refresh by CLEAR.

  10. #60
    Join Date
    Jun 2014
    Location
    Sydney, Australia
    Posts
    17

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    Hi Robbbert, et al.
    Quote Originally Posted by Robbbert View Post
    Characters 192-255 are called Extended Graphics and are entirely in RAM.
    These are normally initialised by the monitor rom to be the *inverse* of 128-191.

    As you say, 128-255 can be redefined after that by your program to be whatever you wish.

    Cheers,
    Red

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