Haha the 755CX was my first "real" PC. I still have it, but the keyboard is in dire need of a replacement. It came originally with Win95 which it runs very well. It also runs Win98 quite well.

How much memory does yours have: These machines have 8MB of soldered RAM, and an upgrade slot for proprietary IBM memory cards which came in 8MB, 16MB and 32MB sizes. They can be still found occasionally on ebay, but can be expensive. I have mine upgraded to 40MB (8+32MB expansion card) which is the maximum they support.

The HDD uses a special caddy which you absolutely need if you want to upgrade the drive. Inside, standard 44-pin laptop drives. I think the maximum size they can take is 3.2GB. You also can still found caddies (+/- drives inside) on ebay. They are compatible with the caddies for Thinkpad 760 and 765.

And one last caveat: if you install Win98 on it, and yours has the Mwave sound/modem combo card, sound and modem will not work in Win98 unless you have the very latest BIOS. That'sbecause all previous BIOS revisions had a bug that prevented that card from working under 98. However, the BIOS file cannot be flashed unless you have both an AC adapter connected, AND a fully charged battery. The last requirement is absolute and as far as I know cannot be circumvented. The batteries in these laptops are at this point almost 30 years old and dead. Even the occasional listing on ebay for "new" TP755 batteries will be dead. So unless this machine has already been upgraded to the latest BIOS, you won't have sound in Win98.

https://www.thinkwiki.org/wiki/Category:755CX

And one more neat thing about these. IBM made 2 expansion docks for them.

Dock I (model 3545) gives you a whole range of connectors, an internal bay for drives, and a SCSI controller. It also has an internal full-length 16bit ISA slot for adding custom cards. Thus you can get around the non-functional sound by adding a sound card there. https://www.thinkwiki.org/wiki/ThinkPad_Dock_I_(3545)

Dock II (3546) is similar but allows for 2 internal full length ISA cards. 😀 I have this one and it rocks. It's also very bulky. https://www.thinkwiki.org/wiki/ThinkPad_Dock_II_(3546)

They both show up occasionally on ebay, but can be expensive.

755CX is a good candidate for a DOS gaming laptop. The screen is right (TFT 640x480) and it has built-in sound. MWave works fine for digital sound. As for FM music, it sounds unusual, but still acceptable.
Don't see the point of installing Windows on it, frankly. P75 isn't really for Windows gaming. If gaming is your aim, of course.

Depending on version, some models (like mine) even have 800x600 screens. And it's TFT so good image quality.
For me, having Windows on it is nostalgic. This was the first computer I owned with Windows on it. 😀 It probably doesn't apply to the OP though.

That's right some models have 800x600. But this particular one seems to be 640x480.
And I agree that it's worth getting a dock for it. It opens up a whole lot of upgrade possibilities: a better sound card witha a MIDI daughteroard and game port, extra HDD, a CD-ROM and even a 5,25 FDD (here is my thread about it Re: Thinkpad Dock I with a 5.25" floppy drive)

stamasd wrote on 2022-01-29, 16:05:

Haha the 755CX was my first "real" PC. I still have it, but the keyboard is in dire need of a replacement. It came originally with Win95 which it runs very well. It also runs Win98 quite well.

How much memory does yours have: These machines have 8MB of soldered RAM, and an upgrade slot for proprietary IBM memory cards which came in 8MB, 16MB and 32MB sizes. They can be still found occasionally on ebay, but can be expensive. I have mine upgraded to 40MB (8+32MB expansion card) which is the maximum they support.

I was assuming the memory card is the pictured KTM-TP 360/8, 8MB Credit Card. No?

stamasd wrote on 2022-01-29, 16:08:

The HDD uses a special caddy which you absolutely need if you want to upgrade the drive. Inside, standard 44-pin laptop drives. I think the maximum size they can take is 3.2GB. You also can still found caddies (+/- drives inside) on ebay. They are compatible with the caddies for Thinkpad 760 and 765.

And one last caveat: if you install Win98 on it, and yours has the Mwave sound/modem combo card, sound and modem will not work in Win98 unless you have the very latest BIOS. That'sbecause all previous BIOS revisions had a bug that prevented that card from working under 98. However, the BIOS file cannot be flashed unless you have both an AC adapter connected, AND a fully charged battery. The last requirement is absolute and as far as I know cannot be circumvented. The batteries in these laptops are at this point almost 30 years old and dead. Even the occasional listing on ebay for "new" TP755 batteries will be dead. So unless this machine has already been upgraded to the latest BIOS, you won't have sound in Win98.

https://www.thinkwiki.org/wiki/Category:755CX

Oddly, though, immediately after starting last night, possibly for the first time in decades, it displayed the correct date. Would that be possible if the CMOS battery died?

stamasd wrote on 2022-01-29, 16:18:

And one more neat thing about these. IBM made 2 expansion docks for them. […]
Show full quote

And one more neat thing about these. IBM made 2 expansion docks for them.

Dock I (model 3545) gives you a whole range of connectors, an internal bay for drives, and a SCSI controller. It also has an internal full-length 16bit ISA slot for adding custom cards. Thus you can get around the non-functional sound by adding a sound card there. https://www.thinkwiki.org/wiki/ThinkPad_Dock_I_(3545)

Dock II (3546) is similar but allows for 2 internal full length ISA cards. 😀 I have this one and it rocks. It's also very bulky. https://www.thinkwiki.org/wiki/ThinkPad_Dock_II_(3546)

They both show up occasionally on ebay, but can be expensive.

Thanks for those links. I have two ThinkPad docking stations in storage. I need to check and see if they're compatible.

Bondi wrote on 2022-01-29, 17:36:

755CX is a good candidate for a DOS gaming laptop. The screen is right (TFT 640x480) and it has built-in sound. MWave works fine for digital sound. As for FM music, it sounds unusual, but still acceptable.
Don't see the point of installing Windows on it, frankly. P75 isn't really for Windows gaming. If gaming is your aim, of course.

I have little or no interest in gaming.

stamasd wrote on 2022-01-29, 17:45:

Depending on version, some models (like mine) even have 800x600 screens. And it's TFT so good image quality.
For me, having Windows on it is nostalgic. This was the first computer I owned with Windows on it. 😀 It probably doesn't apply to the OP though.

Being ignorant of a machine this old, I'm still trying to determine if an OS is currently installed. What's the procedure in Direct Bios Version 5.1.9?

Bondi wrote on 2022-01-29, 18:09:

That's right some models have 800x600. But this particular one seems to be 640x480.
And I agree that it's worth getting a dock for it. It opens up a whole lot of upgrade possibilities: a better sound card witha a MIDI daughteroard and game port, extra HDD, a CD-ROM and even a 5,25 FDD (here is my thread about it Re: Thinkpad Dock I with a 5.25" floppy drive)

I may have a correct docking station in storage. What is the model number for a 755 ThinkPad?

Manhattanman wrote on 2022-01-30, 04:10:

Bondi wrote on 2022-01-29, 18:09:

That's right some models have 800x600. But this particular one seems to be 640x480.
And I agree that it's worth getting a dock for it. It opens up a whole lot of upgrade possibilities: a better sound card witha a MIDI daughteroard and game port, extra HDD, a CD-ROM and even a 5,25 FDD (here is my thread about it Re: Thinkpad Dock I with a 5.25" floppy drive)

I may have a correct docking station in storage. What is the model number for a 755 ThinkPad?

It's 3545-001

Manhattanman wrote on 2022-01-30, 03:52:

I was assuming the memory card is the pictured KTM-TP 360/8, 8MB Credit Card. No?

Yes that's one of the memory upgrade options. They made those cards in 16MB and 32MB also.

Manhattanman wrote on 2022-01-30, 03:57:

Oddly, though, immediately after starting last night, possibly for the first time in decades, it displayed the correct date. Would that be possible if the CMOS battery died?

Note that I was talking about the main laptop battery (the big white pack) not the CMOS battery, as relates to BIOS flashing. The BIOS upgrade is packed inside an executable that checks if the laptop is connected to AC, AND that the main battery is 100% charged; if any of those 2 conditions is not met, it will not allow you to flash.

Bondi wrote on 2022-01-30, 08:09:

Manhattanman wrote on 2022-01-30, 04:10:

I may have a correct docking station in storage. What is the model number for a 755 ThinkPad?

It's 3545-001

3545-001 for Dock I, 3546-001 (or 84G3587) for Dock II. I recommend Dock II as it's much better.

You may also be interested in this: https://archive.org/details/FWVMW058
It's an archive of the IBM downloads for older Thinkpad models as of 20 years ago. I think IBM doesn't have those downloads accessible anymore. The archive is not complete, for instance it doesn't have the BIOS upgrades for 755CX.

The BIOS files were hosted for a number of years by Lenovo after they bought the Thinkpad line, but they seem to have vanished from there as well. https://www.thinkwiki.org/wiki/BIOS_Upgrade_Downloads

(edit) I was wrong, the FTP archive above contains the latest BIOS update. It's file "sytpe144.exe" and it's labeled as "system disk" not BIOS update, which makes it confusing. 😀

stamasd wrote on 2022-01-30, 12:29:

3545-001 for Dock I, 3546-001 (or 84G3587) for Dock II. I recommend Dock II as it's much better.

Better, but much bigger 😁

A small price to pay for 2 working, full-size ISA slots. 😀

Bondi wrote on 2022-01-30, 12:53:

stamasd wrote on 2022-01-30, 12:29:

3545-001 for Dock I, 3546-001 (or 84G3587) for Dock II. I recommend Dock II as it's much better.

Better, but much bigger 😁

Thanks very much for the information you've provided. I'll be back soon - and probably often.

I'm attaching the files for updating the BIOS to version 1.44 (latest) as they can be difficult to find/extract. Files sytpe144.exe and sytpe144.txt are the originals fron IBM, there's also a disk image I made with the extracted files, and a .tar.gz archive of the files contained within that image.