dchou@NCoast.ORG (David Chou) (04/25/91)
I have done this twice in old AT's around our department and I have had the same experience described by the two users. Basically, there are at least two versions of the motherboard and BIOS with regard to the 3.5" drives. The BIOS dated 1985 and later supports a 720k drive without any other support other than a proper setup. These were found on the 8MHZ machines. The 1983 BIOS (6Mhz ATs) had no support for 3.5" drives. We have substituted the B drive in both machines with some limitations for the 1.44MB format as users have described. In the machine with the 1985 BIOS I was able to define the drive as a 720k and successfully read and write 1.44 disks using a Teac, but I could not format the drive success- fully until I replaced the BIOS with a Phoenix upgrade. I suppose it would be possible to write a separate format program which did not work through the BIOS, but I did not try it. On the 6MHz AT, I was able to define an additional drive using the DRIVER.SYS utility and defining the drive as a 360k. Again I had format utility problems. Changing the DRIVER.SYS to indicate a 1.44M drive did not help. I finally changed this BIOS to a Phoenix also. At the time I did these updates, I was able to buy a Phoenix BIOS for ATs for about $50. I see the same BIOS now for nearly $90. Given the cost for a 12-16 MHz 286 motherboards at $100, I wonder about the economics of performing the same updates today. Incidentally, I also needed the new BIOS to support a new disk I had put into the 6MHz AT. David Chou ncoast!dchou@usenet.ins.cwru.edu