Printer Interface Using a Single Microprocessor
Original Publication Date: 1985-Feb-01
Included in the Prior Art Database: 2005-Feb-18
A technique is described whereby an output printer may be connected to three different interfaces using only one microprocessor. This concept eliminates the cost of need for separate interface implementation, software control, and offers flexibility to support the microprocessor bus. Expansion is possible to be able to communicate with any other microprocessor in the system. The three most common interfaces are used: Parallel, Serial RS232 and Serial 20 MA current loop. For parallel interfacing, a single VTL module 9 a 74LS as shown in the drawing is used to generate the busy response to the sending system's strobe pulse. Clearing the busy signal is under the control of the microprocessor's software, which controls the rate of the data transferred on the parallel interface.