AST RESEARCH TECHNICAL BULLETIN TB-0163                   4-24-86


                     ADVANTAGE PARALLEL PORT


AST Advantage!  users have reported interfacing problems  between 
the Advantage!  parallel port and certain printers.   The symptom 
is  no output to the printer when connected to the AST Advantage! 
parallel port.

The  problem  is  an incompatibility between  the  parallel  port 
STROBE  output circuit of the AST Advantage!  and  the  printer's 
STROBE input circuit.

To resolve this incompatibility the IC 74LS05 located at position 
U89  should  be replaced with a 7405.  This needs to be  done  to 
insure  proper  operation.  The  AST Advantage! board  should  be 
returned to AST Research for proper rework.

If  the customer's situation does not allow for the return of the 
product  to AST for rework,  please see detailed instructions  of 
this rework in AST FCN number 008.