PRINTER - WRITE CHARACTER

AH = 00h
AL = character to write
DX = printer number (00h-02h)

Return:   AH = printer status

PRINTER - INITIALIZE PORT

AH = 01h
DX = printer number (00h-02h)

Return:   AH = printer status

PRINTER - GET STATUS

AH = 02h
DX = printer number (00h-02h)

Return:  AH = printer status

Bitfields for printer status:

Bit(s)  Description     
7      not busy when 1
6      acknowledge
5      out of paper when 1
4      selected when 1
3      I/O error when 1
2-1    unused
0      timeout