Int 2F Fn D600  - Heart.com - Installation Check                           [G]

   AX = D600h

Return: AX = 0303h (two hearts) if installed
       ES:DI -> buffer (see #2760)
Program: HEART.COM is a CPU lock-up/critical indicator utility by Mitch Davis.

Notes: Once the host program has identified the address of the data area, it
     can change this to indicate safe/critical, alternate colours, etc.
   The entries for the color table are in char/attrib form.  Every two
     entries form a pair which is alternated between 68 times a minute.
     The first half of the table is for color videos, the second mono.
     Within each half, the first half is for the safe chars, and the
     second for the critical chars.

Format of HEART.COM buffer:
Offset Size    Description (Table 2760)
 00h  8 WORDs  table of colors/attributes (refer to notes above)
 10h   BYTE    flags
       bit 0: program is in critical section, so flash double
             exclamation mark
       bit 1: program is in safe code, so flash the heart character
 11h   WORD    position of heartbeat on screen, normally 009Eh (last column
       of second line)