CardTalk

CardTalk was a HyperCard scripting language extension developed by Apple Computer. It was designed to provide a means for HyperCard stacks to communicate with external devices and systems. Unlike HyperTalk, HyperCard's native scripting language which was focused on manipulating objects within the HyperCard environment, CardTalk aimed to extend HyperCard's reach beyond the screen.

CardTalk enabled developers to create HyperCard applications that could interact with hardware such as serial ports, printers, video capture devices, and other external resources. This functionality was achieved through the use of external commands (XCMDs) and external functions (XFCNs) specifically designed for CardTalk. These XCMDs and XFCNs provided a bridge between HyperTalk scripts and the underlying operating system, allowing HyperCard to control and receive data from external devices.

CardTalk allowed for more sophisticated and interactive applications than were possible with HyperTalk alone. It enabled the creation of custom control panels, data acquisition systems, and other applications that required real-time interaction with external hardware. While not as widely adopted as HyperTalk, CardTalk played a significant role in expanding the capabilities of HyperCard in specific areas.

The architecture involved a software layer that interpreted CardTalk commands and translated them into instructions that the hardware or external system could understand. This layer typically resided within the XCMD or XFCN.

Due to the decline in popularity of HyperCard, CardTalk is no longer actively used or supported. However, it remains an important part of the history of graphical user interface scripting languages.