INT 15 - SYSTEM - FORMAT UNIT PERIODIC INTERRUPT (PS ESDI drives only)
AH = 0Fh
AL = phase code
00h reserved
01h surface analysis
02h formatting
Return: CF clear if formatting should continue, set if it should terminate
Note:   called during ESDI drive formatting after each cylinder is completed

See also: 131A

150F - SYSTEM - FORMAT UNIT PERIODIC INTERRUPT (PS ESDI drives only)