UPDATE: The friendly folks at Applied Science Laboratories were kind enough to share some additional information on this topic.

The material I've posted above is correct with the following qualifications:

1. You cannot use a 25 pin cable from Radio Shack. Use the cable supplied by ASL.

2. ASL Record bit is parallel (LPT) port bit 7 (not bit 1). Recording will be ON as long as this bit is high, and be paused during any time that the bit is low. If you only turn on bit 7, this is decimal 128, hex 80, binary 1000 0000. It won't matter whether other bits are on or not, they can be used for other things if desired. Turning all the bits on (decimal 255, hex FF, binary 1111 1111), as described in the second web link, will certainly start "auto record", but only bit 7 is actually needed.

3. If desired, it is also possible to use parallel port bit 6 to open and close data files. If this option is selected, a file named with the current date and time will open when bit 6 goes high, and will remain open as long as bit 6 stays high. The file will close when bit 6 goes low. Remember that a file can start recording only if the file is opened. If the auto file open option is used turn on bit 6 to open a file; turn on bits 6 and 7 to start recording; turn of bit 7 but leave bit 6 on to stop recording without closing the file; turn off bit 6 to
close the file.