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Garbled printout

Q: When I print bills (or long reports), the first few pages are OK but then something goes wrong and the rest are messed up.

A: The symptoms may include extraneous characters, graphics boxes, strange fonts, missing text, or almost anything other than the proper output. The key observation is that the first few pages are always correct.

This is a "handshaking" problem between Windows and your printer.

Since the printer cannot print as fast as the computer can send data, there is a dialog between the computer and the printer called "handshaking." When the printer's memory is full of data and cannot store any more (until it prints more pages), it tells the computer to stop sending data. When the printer is ready for more data, it tells the computer to send more.

If the computer sends more data than the printer can handle, whether because the printer didn't tell it to stop or because the computer didn't heed the message, data is lost. At that point, the printout will be incorrect. Commands to the printer may be misinterpreted as characters to be printed, or characters to be printed may be misinterpreted as commands. Either way, the printer is confused and the output is wrong.

There can be many causes for this problem, including hardware, such as a bad printer port or a bad cable. Sometimes it is a software problem in Windows or the printer driver (a piece of software usually supplied by the printer manufacturer).