Gemini Industries Printer user manual Interfacing Gemini With Your Computer

INTERFACING GEMINI

WITH YOUR COMPUTER

Your Gemini printer is a remarkable example of modern engineering. A few short years ago, the information-handling capability built into Gemini would qualify the “printer” to be considered a “computer” of sorts. When Gemini is interfaced (“hookedup to”) your microcomputer, the results can be dazzling.

The characters identified in Chapter 3 are imbedded in

Gemini’s mad-on/ymemory(ROM’chips. Your computer doesn’t need to tell Gemini how to print the set of dots that represents a certain character; your computer just needs to tell Gemini which ones and where.

When your computer identifies the characters selected for printing, Gemini stores up to 816 bytes of data in its buffer at the same time that it’s printing. Gemini even knows when it runs out of paper - stopping the printing process and (if you wish) signaling you of the problem.

Before we explore interfacing Gemini with your computer, let’s briefly consider how Gemini’s control circuit is configured. As graphically illustrated in Apendix L (control circuit block diagram), Gemini features a central processing unit (CPU]. This CPU controls the electromechanical operations, such as the print head, carriage motor and paper feed motor. This CPU utilizes the random-access memory (RAM). It receives data serially, or in parallel, depending on which type of interface your system requires.

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