The first disk drives offered on the Model I were Shugart SA-400s which supported 35 tracks and was the sole -inch drive on the market in 1977–78. By 1979, other manufacturers began offering drives. Models 3/4/4P uses Tandon TM-100 40-track drives. The combination of 40 tracks and double density gives a capacity of 180 kilobytes per single-sided floppy disk. The use of index-sync means that a "flippy disk" requires a second index hole and write-enable notch. One could purchase factory-made "flippies". Some software publishers formatted one side for Apple systems and the other for the TRS-80.
The fi.rst disk drives offered on the Model I were Shugart SA-400s which supported 35 tracks and was the sole -inch drive on the market in 1977–78 By 1979, other manufacturers began offering drives Models 3/4/4P uses Tandon TM-100 40-track drives. The combination of 40 tracks and double density gives a capacity of 180 kilobytes per single-sided floppy disk. The use of index-sync means that a "flippy disk" requires a second index hole and write-enable notch. One could purchase factory-made "flippies". Some software publishers .formatted one side for Apple systems and the other for the TRS-80.