Linux on IBM Thinkpad 750Cs

Linux is known to be a stable operating system that does an excellent job of managing the PC's hardware. With that comes the challenge of getting Linux to work properly on some hardware. One particular example is getting Linux to work on laptops. Some brands can be tough to configure, while others are a piece of cake. A particular brand of laptop that works great with Linux is the IBM Thinkpad series. It can be hard to get working at first, especially the X Window System. I am a happy user of Linux on my IBM Thinkpad 750Cs, and this article is a description of what I did to get Linux functioning perfectly.

The IBM Thinkpad 750Cs has an Intel 80486 DX processor. The 750Cs has approximately 20MB of memory and 330MB of hard drive space. The hard drive and floppy drive are both made specifically for IBM. The floppy drive is a 2.88MB drive which shows up in a few Thinkpads, and the video card is a VGA card. These hardware specs are important to know for someone who will be configuring Linux.

I am using Red Hat Linux 5.1 with kernel version 2.0.35. Installing this version of Linux went smoothly. I downloaded the boot and root disk installation images and put them on two floppies. I used a Backpack, 4x speed external CD-ROM drive from Microsolutions Inc. for the installation. The installation program is capable of finding this drive, so that made the rest of the installation run without problems. My only difficulty was with X.

The Thinkpad floppy drive has an inverted disk change sensor that Linux doesn't automatically support. Thus, in order to fix this, I had to pass floppy=thinkpad to the kernel at the LILO boot prompt. This must be done for the installation to complete properly.

Getting X to work on my 750Cs was the toughest part. The problem lies in the 75xCs series of Thinkpads and their dual-scan monitors. X starts, but displays only a black screen with an occasional vertical line. The only way around this problem is to use a program, written by Michael Steiner, that disables the upper 512K of video memory. This program can be downloaded from http://www.zurich.ibm.com/~sti/tplinux.html. After downloading it, I ran xf86config and chose the smallest option for the monitor and a standard VGA card. Since the video card is a VGA card, the only server available is XF86_VGA16. Then Michael Steiner's program must be enabled once before starting X. Use the following command: tpdualscan -e. Note that when the problem first occurred, pressing ctrl-alt-delete wouldn't shut down the computer under that black screen. First, I had to end X by pressing ctrl-alt-backspace, then ctrl-alt-delete to shut down my computer, eliminating the black screen.

Linux supports the Thinkpad's PCMCIA slots perfectly, and since my individual cards were supported, I had no problem here. I personally recommend 3Com's Etherlink III 3c589D card for Ethernet networking, because cardmgr found this card easily and it works fine. I didn't have to edit any of the PCMCIA configuration files.

The two main problems with the Thinkpad are the floppy drive and the XFree86 problem. Linux supports the rest of the computer perfectly. Problems with other Thinkpads shouldn't be too hard to fix, and Michael Steiner's web page is a good place to start for help.