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Joycheck is a program that has the purpose of verifying if the digital joystick and/or the port to which it is connected works correctly, according to the isomorphic characteristics of the "midres" library.

It was initially developed to test whether the joystick signals on the Commodore PLUS/4 platform were read correctly by the library, and then extended to all supported platforms (Commodore C=64, Commodore VIC-20 (expanded), Commodore PLUS/4, Commodore C=128 and Atari 8 bit). It has been written in a short time thanks to the primitives made available by the "midres" library.


Download the right disk image, according to the target platform. Load it on your computer (or your emulator).

Images of all joysticks supported by the MIDRES library for that particular platform will appear on the screen. Now, connect the joystick you want to test or connect a working joystick to the port to test. Move the lever in the various directions, or press the “fire” button.

The “leds” on the interface will change accordingly, thus giving feedback on the correct operation of the various digital switches. The first line of LEDs indicates which bit of the isomorphic byte is being solicited, with respect to that particular joystick port. With this information it is possible to check whether the sign actually reaches the library or not. The second line, on the other hand, represents the decoding of the first line in terms of direction and the fire key.

For example, the image above shows that the joystick connected to the first port has been moved, simultaneously, down and to the left. In terms of isomorphic byte, bits 1 and 2 were stressed.

The program periodically checks all joystick ports. The port that is being analyzed is indicated with a green number, while the others remain designated by a yellow number. As a result, the rapid change in color, from yellow to green and vice versa, indicates that the program is running correctly.

This is the number of joysticks / ports supported for each platform.

Commodore VIC-20 1
Commodore PLUS/4 2
Commodore C=64 2
Commodore C=128 2
ATARI (8 bit) 4



The utility is available for the following platforms: