INT 21,21 - Random Read Using FCB

AH = 21h

DS:DX = pointer to an opened ~FCB~

on return:

AL = 00 if read successful

= 01 if EOF (no data read)

= 02 if ~DTA~ is too small

= 03 if EOF (partial record read)

- reads random records from a file opened with an FCB

to the DTA

- FCB must be setup with drive id, filename, extension,

record position and record length before call

- current record position field in FCB is not updated