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My Toshiba T1100 Repair

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    #31
    Originally posted by CedsRepair View Post
    The new one I got is functional, ...
    Congratulations.

    Originally posted by CedsRepair View Post
    By the way, someone posted here that the manual of the T1100 states that the power brick is 20V (which is true : it is indeed written in the manual)
    But I can confirm the T1100 powerbrick is 18V, not 20V, photo available if that is necessary.
    Photo not needed. There is a photo already (in a link) at [here].

    Comment


      #32
      Well, a bit late as you already decided to stop with the repair and bought another T1100, but maybe some background information on this, that could be worthful for others (or in future for you too...)

      The 80C49 is an improved version of the 8048/49 microcontroller, which was used in the IBM-AT and following generations of PC compatible computers.
      As the T1100 is a XT-Class computer, it is a bit surprising to find that solution inside.

      But to be compatible to IBM Toshiba had to follow IBM at least at the boundaries (interfaces) of each unit. So you can be almost sure, that the 80C49 is programmed in a way that is compatible at the register-level to IBM. As IBM had NO intelligent keyboard-Controller on the PC and XT generation, the interface is rather simple. Details e.g. here: http://minuszerodegrees.net/5160/key..._interface.png

      As in contrast to normal desktop computer keyboard is integrated inside T1100, the 80C49 makes basically the job of the controller INSIDE the separate keyboard of normal computers! The output is a serial stream which is clocked into a latch and then read in parallel form by the PCs processor. (using 8255 PIO in XT class).

      So i would compare the output of a XT-class keyboard (there are simple converters on the market (and also for DIY) to connect even PS/2 style AT-Keyboards to XT machines) with the behaviour of the "unknown" Pins of the 80C49 ( all pins used for scanning the key matrix are easy to find out and are out of race for this part...), starting with the pins which are used inside the Keyboards (find an elder one and you will find 8049 or similiar inside too!) One line is simply some kind of clock, which starts after a signalisation from the keyboard, that new data is available, the other pin is serial data. (the starting signal is part of Data which normally is high-active but is tied to GND if new keypress-data is available) Clock is generated by the T1100, not the 80C49!

      Then cut through the traces from the 80C49 (or even unsolder the 80C49) and connect a XT Keyboard-Connector instead. Finished!

      With this infos you can at least connect an external XT type keyboard already. To use the internal one, you would have to programm a 80C49 (to be able to solder it in without any change of Pins...) or at least any small controller like PIC18F or ATMEGA to scan the keymatrix and send the matching keycodes to the T1100 using a serial slave register, available as "SPI" in almost any controller today. The table of Scancodes is found again in IBM documentation for XT (IBM 5160).

      There is a small chance (as AT was already out at the time Toshiba introduced the T1100), that T1100 even has the improved AT-Interface (which you would find out while watching the signaling on the working one as it is slightly different from XT), but that would make it even more simple: there are thousands of different Computers outside, that have such 80C4x as an AT-Keyboard-controller onboard, some notebooks (like Sanyo NB17/18 -also sold as Commodore LT286/LT386sx) even had the same smd version there... *) So you can use these chips to connect an external AT Keyboard at least. If you want to use the internal one, you can -like above- program your own code (IBMs Code for AT Keyboard-controller is available on the internet as a template) or reuse the chip found inside any external keyboard and adopt the keyswitch-matrix to match the Toshiba one...

      Sounds like big work, but is rather uncomplicated, especially now that you own a working one making it easy to find out the function of every pin. IBMs hardware manuals for XT and AT will be a great help for that too...

      *) these notebooks had TWO Keyboardcontrollers on board: the one which normally sits inside the external keyboard and the one which always sits as part of the chipset on the mainboard of any PC-AT or later computer. This was made to be 100% compatible and also this allows for an easy connection of external keyboards alternatively to the internal one. (but this feature was not used in these models for whatever reason...)

      Good Luck!

      Rudy

      Comment


        #33
        Kangurudy thanks for the detailed write-up, and welcome to the forum!

        - Alex

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