Design Ideas July 20, 1995

Connect IEEE-488 devices to parallel port

Johannes Sturz,
Texas Instruments, Freising, Germany

The circuit in Fig 1 connects IEEE-488 printers and plotters to a parallel port, using only 10 buffered inverters (74HC or 74LS). Moreover, the conversion speed is much higher than that of some expensive "intelligent converters," and you don't need to install a special software driver.

Most parallel-port signals correspond with the IEEE-488 interface but have inverted polarity. You can directly wire only the NSTROBE line. A possible disadvantage of this interface converter is that no information is available for error handling (for example, "paper empty" and "on/off"). However, you can configure the IEEE-488 interface of the device of interest to set the SRQ line for any error.

Note: You must switch the IEEE-488 device into "listen- only" mode because this interface converter isn't able to address the IEEE-488 device. Consult the operating manual of the device. (DI #1734)

PICTURE 1

The right side of this diagram gives the pin arrangement for ribbon cables. This parallel-port pin assignment is for PCs only.