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Thread: ti99 disk controller

  1. #1

    Default ti99 disk controller

    Hi guys

    my ti99 disk controller seems dead - light on but no response.

    However it has a 3.5 inch disk connected...is there anything special about adding a 3.5 rather than the 5.25 of old?

    cheers
    mike

  2. #2
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    Slightly, yes. The TI-99/4a uses a traditional "Sugart" style interface that permits addressing up to four drives, has a single motor enable, and connects via a flat cable.

    Most 3.5" drives expect an IBM PC style FDC with twisted cable. If the drive does not have a "0", "1" (first, second) drive switch then you will probably have to wire a special cable. Look up the "Sugart" vs "IBM PC" floppy controller pinouts to see the difference.

    Other than that, a 3.5" drive with low density disks will work just fine as a substitute.

  3. #3

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    thanks for the reminder its been a long time...

    Hi yes isn't it the drive 1,2 or 3 pin thats different or something. as i recall a standard non twisted pc floppy cable makes it DSK2

    however mine does nothing ,no drive light or anything. i can see someones been at it at some point with a soldering iron...


    Quote Originally Posted by SomeGuy View Post
    Slightly, yes. The TI-99/4a uses a traditional "Sugart" style interface that permits addressing up to four drives, has a single motor enable, and connects via a flat cable.

    Most 3.5" drives expect an IBM PC style FDC with twisted cable. If the drive does not have a "0", "1" (first, second) drive switch then you will probably have to wire a special cable. Look up the "Sugart" vs "IBM PC" floppy controller pinouts to see the difference.

    Other than that, a 3.5" drive with low density disks will work just fine as a substitute.

  4. #4
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    Which disk controller do you have? Could make for a difference in terms of what formats are on disk. I think the PEB controller would create disks double sided, single density, 40 track (90 kB a side) which will look weird to any other 3.5" system.
    Soldering iron may mean you have an upgraded controller making it more interesting but also harder to troubleshoot. I suggest checking that the user soldered components didn't break loose.

    Check some TI-99 related web pages. There were instructions to create twisted cables used for 3.5" drives that lacked DS jumpers. Different from PC twisted cables because only drive select wires need swapping.

  5. #5
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    Quote Originally Posted by mjnurney View Post
    Hi yes isn't it the drive 1,2 or 3 pin that's different or something.
    Some drives are numbered 0,1,2,3 and others are numbered 1,2,3,4.
    IBM chose to always use the second jumper and make the A: or B: selection by putting a twist in the cable.
    TI chose to use a straight-through cable and do the drive selection (DSK1 or DSK2 or DSK3) with jumpers.

    What you describe is exactly what you'd see if you took a drive from a PC to TI without changing the jumper; the controller looks for DSK1 but the drive is set for DSK2.
    If you're using a Disk Manager module, try selecting DSK2.

  6. #6

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    I’ve just tried the cor comp peripheral test and it says no controller found... maybe it’s a dud.

    Is there and diag software to recognise the card regardless of wether a disk drive is fitted?

    thanks guys.
    Last edited by mjnurney; April 21st, 2018 at 12:39 AM.

  7. #7

    Default

    Should the LED be on all the time > mine is...

    ive run an extended basic program to test the card but it shows nothing sadly.




    Quote Originally Posted by mjnurney View Post
    Iíve just tried the cor comp peripheral test and it says no controller found... maybe itís a dud.

    Is there and diag software to recognise the card regardless of wether a disk drive is fitted?

    thanks guys.
    Attached Images Attached Images
    Last edited by mjnurney; April 23rd, 2018 at 09:13 AM.

  8. #8
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    If the LED is on all the time, that tends to mean one cable is installed incorrectly.

    You might consider taking pictures of the modifications to the controller to check if anyone remembers information about the specific setup you have.

  9. #9

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    Hi

    The LEd is on all the time without a cable or drive connected. I did try to add pics but the process seems a bit archaic. Iíll have another go.

    The LED should only light up when the drive is accessed ?


    Quote Originally Posted by krebizfan View Post
    If the LED is on all the time, that tends to mean one cable is installed incorrectly.

    You might consider taking pictures of the modifications to the controller to check if anyone remembers information about the specific setup you have.

  10. #10

    Default

    Great ... the 32k card has packed up now..

    No 32k found and disk controller led always on.

    Could this be a bad flex cable and board I wonder...

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