The latest video from Jaroslav Sykora takes a closer look at how the X65 Interrupt Controller manages communication between the CPU and external devices. Using a compact assembly program, the demonstration explains how an 8-bit system like the X65 maps hardware components directly into memory for seamless access.
The program itself runs an endless loop, reading a specific memory cell and printing its contents in both binary and hexadecimal formats. It also includes a simple liveness indicator—a flickering line of pixels—to confirm that the program is running correctly. Although it appears minimal, this loop forms the foundation for understanding how hardware interacts with the system at a register level.
Each value displayed corresponds to a register in the X65 Interrupt Controller. This hardware component tracks which devices are generating interrupts and signals the CPU accordingly. The X65 supports eight interrupt sources in total, with the first three being internal and the remaining five available for external devices. By connecting resistors to the expansion port, Sykora demonstrates how each interrupt line responds to changes in voltage, flipping bits in the register in real time.
The test setup includes four resistors linked to external interrupt lines on the X65’s expansion port. When a resistor is grounded, the corresponding bit in the memory register changes, confirming the line’s functionality. This simple yet effective test validates the correct behavior of both the controller hardware and its firmware.
Through this demonstration, the X65 Interrupt Controller proves its reliability and accessibility. By using standard memory mapping, external devices can communicate with the CPU without complex protocols or dedicated instructions. The video ends with a successful verification of the expansion port’s interrupt system, reinforcing how cleanly the X65 integrates traditional 8-bit architecture with modern flexibility.
