Earlier this month I reported the results of using a large HD (30 Gb) with DOS (6.22) partitioned using Partition Magic. I had created three, 2.1Gb logical drives on the large (second) HD and jubilantly reported that I could access the logical drives from the first HD. Then things went to hell in a handbasket!
Background: P5-75 pentium computer running MS-DOS 6.22. Installed Promise's DriveMax BIOS upgrade card which modifies the BIOS to permit access to HDs up to 128 GB. To test out the DriveMax card, I used Partition Magic (PM) to create three, 2.1 Gb logical drives on the 30 Gb HD and was pleased that I could copy files from the first HD (850 Mb) to the second HD using DOS' Copy command and could also read the files from the first HD. I then decided to copy *all* of my drives (C: thru K:) from the smaller HD to the larger one so that I could move the smaller HD to another machine. Using PM, I moved the three large logical drives out of the way so that I could copy (using PM) the primary and logical drives from the first HD to the second. The copying went fine; PM showed all the files in the larger HD, so I shut down, set the 2nd drive as a primary HD, disconnected the 1st HD, booted using a rescue floppy, changed the CMOS parameters, and rebooted. I now could not find any logical drive beyond D:! [I won't go into the details of all the futzing around that I did for 2 days, except to say that I deleted all the drives that I copied from the 1st HD and moved the three 2.1 Gb logical drives back to the beginning of the 2nd HD.] While trying to go to sleep, I remembered a message that PM briefly flashed when I first moved the three 2.1 Gb logical drives that it was increasing the size of the DOS extended partition to accommodate the move. I went back in to PM and resized the extended DOS partition on the 2nd HD to 7.6 GB, rebooted, and VOILA!, everything was back to normal! I could now do everything that I could do right after I first created the 2.1 Gb logical drives. A little more experimenting showed that the DOS extended partition has to be less than 8.2 Gb (Giga*1000bits), or 8.025 GB (Giga*1024bits). Promise's DriveMax appears to work as advertised as the entire 30 Gb HD is accessible to PM, but apparently DOS's limitation requires that extended partitions be less than 8.2 Gb. Hope this helps any of you who are thinking about putting a large HD in your computer and using a BIOS modification card or software to access the large HD. Roger Turk Tucson, Arizona USA
