Z80 Assembly 77: Interrupt-Driven Printing (Spooling Data)
The Drawback of Polling Printers are extremely slow compared to the Z80 CPU. If the main program waits for the NOT BUSY status bit (Part 76) after sending every single character, the CPU spends most of its time sitting idle, waiting for the printer to finish. The Solution: Interrupt Spooling Spooling (Simultaneous Peripheral Operations On-Line) uses interrupts to feed the printer one byte at a time in the background, allowing the main program to continue executing tasks. ...