Thinkpads Forum

I recently got a IBM Thinkpad 750c in good condition (well, except for some very sticky rubber coating). The computer starts, but get stuck at error code I9990303, which seems to be related to the harddrive. The drive spins up, and works when using it with a 40 pin to 44 pin adapter on another PC. It seems to have had PC DOS 7 and Stacker disk compression on it, but is not bootable in either machine. I tried reformatting the harddrive with the /s option, but the Thinkpad still won't boot from it.

From what I can read on the net, there may need to be a hidden partition on the drive (which it didn't have, even before I reformatted it) that is needed for the computer to boot, but I couldn't find much information on that, and I'm not even sure this really applies to the 750c. The floppy drive either doesn't work, or the computer still needs the hidden partition to get that far along. It lights up, make disk spinning and seeking sounds, but doesn't boot from it, and the computer still ends up at the I9990303 error.

How can I make it boot? Does anyone have a working disk image I can write to the drive, or knowledge about any tools that can be used to recreate it? Or any other tips in general for a machine like this?

Get the tpvol2.pdf manual from the HMM link above.
According to that, error I9990303 = System Board.

Thanks! I guess that's both good and bad news, but that document is a wonderful source of information. You wouldn't happen to know exactly what kind of failure on the system board could cause that error? Could replacing capacitors solve it? Most of the machine has to be in working order to get that far.

And hey Google! Thinkpad 750 manual should lead to http://greyghost.mooo.com/pccbbs/mobiles/tpvol2.pdf

The I9990303 error is normally associated with the IBM PS/2 series of computers. Some PS/2 models required a "Reference Partition" on the hard drive, and typically you would load the appropriate Reference and Diagnostic diskettes into that small partition so that you didn't have to boot diskettes to configure new or changed Microchannel adapters or otherwise change the system configuration. Thinkpads do not require a "Reference Partition", but IBM shared BIOS code sections between the PS/2 and Thinkpad line, so some Thinkpad errors can look rather strange.

I just purchased a 750C on eBay and it has a I9990303 error that I'm trying to clear, at the moment I'm trying to charge up a main battery pack and recharge the backup battery. Unlike most later Thinkpads, the 750 series used a VL2330 rechargeable coin cell battery for the backup battery, and it has a 3 cell standby battery that is also rechargeable. Once I have the various batteries charged up, I'm going to try to update the BIOS firmware using the diskette I created from the SYTPS142.EXE file I downloaded from the Internet Archive (https://archive.org/details/FWVMW058). If that all goes well and I can get back into EZ SETUP, then I plan to move the system board assembly from this 750C and put it into my 750P which does not POST at all. My goal is to get the 750P working properly since it has a good screen and the eBay 750C has a badly cracked screen that is only readable in about 10% of the display.