Can I upgrade the BIOS to add high-density floppy drives?
The TL/3, RLX’s, and RSX’s can take high-density drives, though the TL/3 did not come with one. The RLX will not take low-density drives. Other models require that a secondary controller be installed in an expansion slot to add high-density drives. There was a rumor that an AMI or Phoenix BIOS upgrade for the IBM XT could be used in a Tandy 1000-series, permitting high-density drives to be used with the built-in controller, and providing BIOS support for hard drives. The rumor was false. In most 1000-series, the built-in controller cannot support high-density drives because the data separator will only run at 250k bps. In the SL and TL, the data separator is capable of running at 500k bps, but the data rate pin is hard-wired to 250k and the drive speed pin on the floppy cable is not connected. In addition, an IBM BIOS chip would not support Tandy-specific features such as the weird video memory mapping and the digitized sound functions on the SL/TL. Tandy says: Tandy Corporation/Radio
