MS-DOS 1.25 [TI Professional Computer OEM r1.13] Released in 1983 by Microsoft/Texas Instruments For the Texas Instruments Professional Computer Image Quality: Unused/Unmodified (Disk had some physical damage) Labeled as "MS-DOS Operating System version 1.13", This is the special OEM version of MS-DOS needed to operate a Texas Instruments Professional Computer. It contains IO.SYS 1.13, MSDOS.SYS 1.25, COMMAND.COM 1.17, and support utilities. Important: This disk will ONLY boot on a TI Professional Computer. It will NOT boot on an IBM PC, IBM hardware compatible PC, or a PC emulator. This archive contains one 5.25 320k (DSDD 8 sector) floppy disk image. TI Professional Disks are formatted with an interleave of 1:2 instead of 1:1. If you use a sector copying tool, you must make sure the tracks are formatted appropriately.