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BIOS for Toshiba T2100

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    #16
    Thanks modem7. That appears to work. Is there a Debug command, or otherwise, by which I can verify I actually have the BIOS contents please?
    Last edited by pavery; October 10, 2021, 11:32 PM. Reason: Added 'please'.

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      #17
      Originally posted by pavery View Post
      Thanks modem7. That appears to work. Is there a Debug command, or otherwise, by which I can verify I actually have the BIOS contents please?
      The photo in your post #12 shows that the motherboard BIOS chip is a Toshiba TC57256. Because I know that that can be replaced by a 27C256, I know that the BIOS chip is 32 KB in size. The motherboard BIOS normally resides at the end of the upper memory area, so for 32 KB, that corresponds to address range F8000 to FFFFF.

      If you post your MYF800.BIN, we can look at it, and make an educated opinion.

      The only real way to fully verify the content of MYF800.BIN would be to burn it to a 27C256 chip (speed rated at 200 ns [or faster] like your TC57256), then use that chip to replace your TC57256 chip.

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        #18
        Thanks modem7. I'm just skeptical of the .BIN file created as whilst the directory shows it is 32KB in size, it took a whole lot of Retries and Ignores to get it saved down on to floppy. What I'm thinking is... is there a way in Debug to show the first few bytes of the BIOS chip in hex and maybe the last few bytes? The disk drives: while I'm familiar with 5.25" 360KB repairs, I've never worked on 3.5" Is it likely they just need a head clean & rails/mechanism cleaned/freed up?

        In any case I shall attempt to get a 3.5" drive fitted to my 98SE PC so I can get this .BIN file to you & Branko.

        Many thanks
        Philip

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          #19
          Originally posted by pavery View Post
          ... is there a way in Debug to show the first few bytes of the BIOS chip in hex and maybe the last few bytes?
          Yes. See [here] for an example of showing some bytes from address C800:0 (C8000) onward.

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            #20
            pavery
            I use simple command "fc.exe /b file1 file2" to compare two binary files but it is useful only if you have second file to compare with. We can try it with the bios dump I have, but it is different version.

            As modem7 mentioned, the best would be to burn these in into some chip and try. Send me your bin files on btrenkoski (at) penluchi.com and I will give it a try. I didn't know that there is a cheap replacement 27C256 I paid 20EUR for original EPROM

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              #21
              Originally posted by silence012 View Post
              I didn't know that there is a cheap replacement 27C256 I paid 20EUR for original EPROM
              I got the information from someone who replaced the TC57256 in their Toshiba T1000. See the comment against the BIOS ROM in the photo at [here].

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                #22
                I just checked pinout and they are the same. So definitely it can be replaced. I will test it, as many of Toshiba's old laptops uses this chip. Thanks modem7

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                  #23
                  OK, I believe we have success. My good friend Tezza (who happens to be a vintage computer gonzo) came around yesterday & we made progress. We found bad media was some of the problem so Tez cleaned the 3.5" drives with his cleaning disk. We made new copies of the T2100 MD-DOS 2.11 disk & sorted out 3.5" install into my 98SE/XP box.

                  So here is the result of BIOS dump. (Had to rename it from BIN to TXT so upload was accepted). Have looked at it in Hex Viewer & the first lines at least match what Debug df800:0 displayed.

                  Is there a battery on the motherboard? As there is a RTC, I presume so. If so, I should remove it to prevent leakage. Branko, do you know where it is, so I don't have to dismantle the whole machine? Do you have a photo of the motherboard?

                  Philip

                  Attached Files

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                    #24
                    Originally posted by pavery View Post
                    So here is the result of BIOS dump. (Had to rename it from BIN to TXT so upload was accepted). Have looked at it in Hex Viewer & the first lines at least match what Debug df800:0 displayed.
                    Thanks. I have added the image to the collection at [here].

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                      #25
                      Originally posted by pavery View Post
                      Is there a battery on the motherboard? As there is a RTC, I presume so. If so, I should remove it to prevent leakage. Branko, do you know where it is, so I don't have to dismantle the whole machine? Do you have a photo of the motherboard?
                      See the photos at [here].

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                        #26
                        Thanks modem7, those links are very helpful. Also thank you for all the resources at http://www.minuszerodegrees.net

                        Philip

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                          #27
                          pavery sorry for the late response. Yes, there is a battery (as modem7 send on link) and you should remove it asap. I was lucky enough that my battery was not leaked

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                            #28
                            I disassembled the laptop & sure enough found a leaking on-board Ni-Cd with a degree of green fuzz underneath. I unsoldered it and cleaned up the fuzz with White Vinegar, then IPA. The drives & laptop are now 100% stable. Furthermore after some use the blank pixel column on the gas-plasma has come back into service and has been solid for 2-weeks now. Thanks for the help - a T2100 is now back in the land of the living.

                            20211120_141325[1].jpg

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                              #29
                              pavery Happy to hear that you fixed it.

                              Cheers!
                              Branko

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