Z80 Assembly 76: Printer I/O and Parallel Data Transfer
The Challenge of Parallel Data Transfer Unlike serial communication (sending one bit at a time, Part 40), parallel communication sends an entire byte (8 bits) simultaneously across 8 dedicated data lines. This requires additional lines for handshaking to ensure the slow peripheral (the printer) is ready to receive the data. Printer Ports on the Spectrum The ZX Spectrum often uses an external interface (like the ZX Interface 1 or Kempston printer interface) to add parallel output capability. These interfaces typically map to two adjacent I/O ports: ...