VTX5000: Part 2 - Hardware

This article provides a detailed technical analysis of the VTX5000 hardware, a Prestel terminal for the ZX Spectrum. It explores the device's internal components, including the NEC D8251AC (Intel 8251 clone) USART for serial communication, the modem, and viewdata display circuitry. The article discusses the minimalist I/O address decoding using A7 line, the 8251's status register, and the device's design choices, such as the pass-through cable for daisy-chaining. It also touches on potential baud rate capabilities and the historical context of the hardware's development by Prism Microproducts and O.E. Ltd.