File System used by Texas Instruments TI 99/4A groups.google.com.au/group/comp.sys.ti/browse_frm/thread/64cc9c35e36ebb28/6f3faa2ae6b0e4d2 ftp.whtech.com/datasheets%20%26%20manuals/Specifications/File%20Management%20Specification%20for%20TI%2099_4%20Personal%20Computer%20V2.5%2002-25-1983.pdf