INT 2F - AVATAR.SYS - QUERY DRIVER STATE
AX = 1A3Fh (AL='?')
ES:DI -> buffer
CX = length of buffer in bytes
Return: CF clear
CX = actual size of returned info
Note:   the returned information consists of multiple letters whose meanings
are described under AX=1A21h

See also: 2F1A21

2F1A3F - AVATAR.SYS - QUERY DRIVER STATE