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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.