Pulling Out My ThinkPad 755Cs

thinkpad755cs-1One of my earliest laptops is this IBM ThinkPad 755Cs dating back to 1994. According to the website ThinkWiki this model came with a colour display, either a 486 DX2 50 or DX4 75 Mhz processor, 4 MB RAM, 1 MB Western Digital WD90C24 video, Cirrus Logic CS4248 for audio, and a choice of a 170, 340, or 540 MB hard disk drive.

This particular one was maxed out with the DX4 processor and 540 MB drive, so it fetched some decent coin when new. It had also been upgraded to 20 MB RAM at some point.

The 755Cs sat above the 360s (e.g. 360C, 360Cs, etc.) which were a somewhat more affordable option coming with a 486 SX 33 or DX2 50 Mhz processor. Viewing some magazines in mid-1994 the 755Cs with the DX2 processor, 4 MB RAM, and 170 MB drive was priced at $3,599 US according to an IBM advertisement. The 360Cs was advertised beside it but for $1,000 US less with the 486 SX processor.

I purchased this with another ThinkPad of similar age from eBay rather cheaply about 3 years ago or so. The seller didn’t have the right AC power adapter so I was taking a punt as to their condition. Fortunately from buying another ThinkPad beforehand requiring the same power source, I was able to test them. The other laptop would turn on but had a power-on password, making the laptop only really useful for parts. This laptop thankfully had no password and it worked!

It was discovered to have been running Windows for Workgroups 3.11 with Microsoft Office and SAP installed. Without much effort, it was obvious it had been an ex-corporate laptop from a defunct Australian airline, Ansett Australia that were placed into insolvency in 2002. Whoever used it for work had this horrible fluorescent pink desktop scheme – don’t know how someone could look at that working in Excel all day!

Having not used it for some time, I decided to pull it out and give it a spin. Typical from having no good CMOS battery inside, it asked for the current date and time. After confirming this, initially I didn’t get far.


The ThinkPad 755Cs in the BIOS after detecting memory issues.

The 201 error message was appearing which signifies a problem with memory. My initial reaction was the original 4 MB RAM had gone bad.

IBM had designed this laptop with ease of access in mind, apart from the motherboard which is split in two by the back. Moving a couple of latches on the side, the keyboard easily lifts up and you’ll find the floppy drive, battery, and the hard disk all accessible. Using the blue tags allows for easy removal of these components.


Lifting up the keyboards shows how easy it is to remove components.

Naturally you may have expected to access the RAM chips on the back of the laptop. Instead this model and other early ThinkPads from the 300 and 700 range were to use an IC DRAM Card. Although similar in appearance to a PCMCIA card, they were not compatible. Memory sizes came in 4, 8, and 16 MB variations.


The 16 MB RAM expansion card underneath the floppy drive.

I decided to pull out the card and see if it made any difference. Thankfully it did. I managed to easily boot up into MS-DOS 5.0 that was on the hard disk when I had reformatted it some time ago. Windows 3.0 was also installed.

Placing the 16 MB card back in, the 201 error message didn’t appear again fortunately.

After given the hard disk a format, and loading up MS-DOS 6.22 and Windows for Workgroups 3.11, the only niggling issue was the floppy drive during installation. Files would copy, but then the occasional disk read error would occur. Having a couple of disk sets for both helped get past this. Next will be finding the drivers for it.



Fresh copy of Windows for Workgroups 3.11.





2 thoughts on “Pulling Out My ThinkPad 755Cs

  1. Roger Fix says:

    Really enjoyed your post in regard of old SW. Keep up good work, dig your site, but please update at least once per week.


    • Josh says:

      Thanks for the feedback. Unfortunately due to other commitments in life, updating every week isn’t feasible, but hope to add some new additions in the near future.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s