Technology11 minutes
VTX5000: Part 4 - Comms routines
In part 3 we saw how the VTX5000's 8K ROM is structured and how the BASIC program drives the terminal. Now we'll look at the Z80 machine code that handles the real-time work: talking to the 8251 USART, managing the ring buffers, and scanning the keyboard with its Prestel-specific remapping.
