Adding a Second Hard Drive You should be able to add a second IDE (Integrated Drive Electronics) hard drive to any empty drive bay in your system as long as it is 100% CAM (Common Access Method) and has no more than 1024 cylinders. While this does not exactly limit the capacity of the drive, drives that meet these specifications are usually no larger than 512-520M. Just remember that in a system with two IDE fixed disks, the C: disk is the master disk and the D: disk is the slave drive. IDE disks can be configured in one of three ways: as the only disk (master without a slave), master drive with a slave, or slave. These settings are determined by jumpers on the drive (check the manual that came with your hard drive or call the manufacturer for jumper settings on specific make/model hard disks). The hard disk that came with your PS/1 is configured as a master (some disks, such as the ones in PS/1's do not distinguish between the only disk (master without a slave) and master drive with a slave). Just make sure the second drive is configured correctly (as a slave drive in a two hard disk system) and there should be few problems, but back up your original hard drive just in case. Basically, IBM designed the 2133, 2155, and 2168 PS/1 computers to use either one or two standard, IDE hard drive(s). Since the IDE standard defines drives with 1024 or fewer cylinders, these new, larger drives with more than 1024 cylinders are not, technically, IDE drives. They may conform to the newer EIDE (Enhanced IDE) standard, but any hard drive with more than 1024 cylinders cannot be an IDE hard drive. Since these are not IDE drives, IBM cannot guarantee that they will work any more than SCSI (Small Computer Systems Interface) or any other non-IDE hard drives. As for the advice from Western Digital, On-Track, etc., we simply pass information along as we get it. The README.CAV file that comes with the On- Track software disk supplied with the larger Western Digital hard drives has this to say about PS/1's: "These systems will support drives with up to 1,024 cylinders. It is not possible to obtain full capacity on some 486 models because of the way these machines cloak, or hide from view, the hard disk registers. This prevents Disk Manager from 'seeing' the drive." As for the user success stories, we have no control over them. They have surprised us quite a bit, based on the earlier reports we have received from other, unsuccessful users and the aforementioned information from Western Digital and On-Track software. Some of the users were installing 540M disk drives, and their PS/1 may only be "seeing" the first 1024 cylinders, which provides them almost all of the drive's capacity (more than 95%). If they see the unformatted size of the drive and mistake it for the formatted size, it is easy to see why they could believe they are accessing all of the drive. Unless we see a user account to be false or misleading, we will leave them in the Info Exchange (even if they describe configurations we cannot support). If you have any questions about this procedure, please post a note in the appropriate topic or forum area. Be sure to include your DOS version and your model number (i.e., 2155-G82).