I have several 1990s ThinkPad laptops which all have PCMCIA slots. Some have a built-in CD-ROM and no floppy drive, and no support for CD booting. It would be rather useful to boot them from PCMCIA ATA cards, and the BIOS looks like it supports that. But in most cases it just doesn’t work. Does anyone have relevant experience?
Here’s what I tried so far. I have a ThinkPad 560X which does boot from PCMCIA ATA devices. The BIOS basically treats the card as a regular hard disk. As long as the card has appropriate MBR, partition table, and bootable operating system, it works great. I successfully booted a Toshiba ATA flash card and an IBM 1GB Microdrive (in a CF to PC Card adapter).
The same cards refused to boot in a ThinkPad 760XL and 765D. The BIOS boot device configuration is the same as on the 560X but it just doesn’t work. Unfortunately there does not appear to be any way to diagnose what is going on.
I found this IBM document which suggests that booting from PCMCIA ATA cards should be generally supported by 300/500/600/700 series ThinkPads. But the document also contains this ominous sentence: “Actual customer use of ATA devices as boot drives has been extremely infrequent.”
The nice table on thinkwiki has far too many question marks to be very useful, unfortunately. The 76x ThinkPads aren’t even listed. The table does confirm that the 560X is known to work.
So what’s the deal? Is PCMCIA boot simply broken on many ThinkPads, even though the BIOS offers it as an option? Am I doing something wrong? Are there only specific BIOS revisions that work, and/or specific devices? The Internet is silent, at best showing questions but no answers.
For obvious reasons, if this worked it would be rather useful—a bootable PC Card in the 500 MB to 1 GB range can contain all the tools one needs, is very portable, and in the case of Microdrives can be easily hooked up to a modern system. Superior to floppy booting in every way, especially when many of these laptops don’t even have a floppy drive built in and need either an external one or a dock.
Update: ThinkPad 755C (486 DX4-75) with BIOS from 10/14/1994 can boot from some PCMCIA ATA devices. It boots from my Toshiba 640MB flash ATA PC Card and from two different CF cards (500MB and 1GB) in a CF to PCMCIA adapter. A 1GB IBM Microdrive (which worked in the 560X) did not work on the 755C.
A slightly older 6/14/1994 BIOS on a different 755C (DX2-50) works as well. Worth noting that on the 755C it is clearly visible that the PCMCIA activity indicator lights up several times during POST. Unfortunately the 76x/77x series laptops have no such indicator.
Late Update: ThinkPad 755CDV (Pentium 75) with BIOS from 01/18/1996 works even better. It can boot from the Toshiba PCMCIA ATA flash card, from a 1GB Microdrive, from the 500MB and 1GB CF cards, and from a Maxtor MXL-105 PCMCIA hard disk. In other words, every PCMCIA ATA device I tried worked.