160K (single sided, 8 sectors):
DOS100.IMG      single sided DOS
DIAG100.IMG          "
6172230.IMG          "            purple label IBM Diagnostics part 6172230
DOS105.IMG      dual sided DOS (1st drive is A,B; second is C,D; no HD's yet)
  320K (double sided, 8 sectors):
DOS110.IMG      first true double sided DOS
  360K (double sided, 9 sectors):
DOS202.IMG      supports HD, subdirectories