Locked out of Toshiba T4800CT

Hi all

I wanted (and still want) to get a working 486 system that fits into my limited storage space so I went ahead and ordered a Toshiba T4800CT from Ebay. I thought this was a fairly safe buy because I already have a dead T1960CT for parts and the T4800CT appears to be mostly working already. The listing showed it displaying a completely black screen with plain text saying "Password = " followed by a cursor in the top-left corner. I thought this was simply a BIOS passsword which could be reset by removing the CMOS battery.

Fast-forwarding to now, I have partially disassembled this and removed the only battery I could find attached to the main board that has the CPU. It is around the size of an AA battery with "Ni-MH" written on it. A few hours later I reconnected the battery, turned the system on and found that it still requested a password. This still happens if I start it with no hard drive. I can't seem to get into the BIOS settings. I'm also unable to type anything when it asks for a password but I think the keyboard works because pressing enter causes it to beep at me. It beeps once when I press enter the first two times. On the third time, the beep continues until I press the power button.

Does this password screen look familiar to anyone and if so, how can I get past it?

Thanks in advance for any help


  • According to this site:

    In addition to the NiMH Ram Battery, there is a Cmos/Real Time Clock Battery
    Picture at:

    You need to disconnect this CMOS battery to reset the Logon PW.

  • Thank you altracker9

    I have disassembled the T4800CT again and I didn't find this battery. I had the main motherboard completely out in my hand so there were no batteries connected to it for at least 10 minutes. The circuit board that handles power also came right out. I've now put it all back together and it still asks for a password.

    I could see two other boards in there. One is for the sound (even though I'm pretty sure it only has the internal buzzer) and one is for the other ports on the back of the laptop.

    Am I correct in assuming the BIOS details are stored on the same circuit board as the main processor?

  • I pulled this apart again and managed to find this elusive battery. It was located underneath the floppy drive and was not easy to get to. It looks the same as the picture except that it is cased in clear heatshrink instead of black and it says "Li" on it. I measured its output at 0.28 volts. It had leaked but not enough to damage anything else. I have now removed this battery so that it doesn't leak any further. It took me 45 minutes to put the laptop back together and I now am still prompted for a password when I turn it on without this battery in it. I will try again in a few days in case there's a capacitor holding some charge.

    The frustrating thing is that this is the only 486 system I have which I think actually works and I can't use it. At this point I suspect the password is stored in non-volatile memory.

    I would greatly appreciate any information on how this password is stored or any relevant knowledge that I might not have.


  • I am still not getting anywhere with this password after waiting a few days. I also found this forum thread which has a little bit of info on this topic.

    There may still be some hope though. I have just found and ordered a non-working T4700CT because I may be able to get something working by combining these two systems. They are so similar that they share the same service manual.
    http://www.minuszerodegrees.net/manuals/Toshiba/Other/Toshiba T4700CS T4700CT T4800CT - Maintenance Manual.pdf

    I will keep this thread updated with my progress.

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