The Acorn Electron is a Synertek 6502-based computer that was released in the UK in August of 1983. It’s a budget version of the well-known BBC Micro educational/home computer, with 32 kB of RAM and featuring BBC BASIC v2 in its ROM. [Roland]’s ElkWiFi card slots into an available cartridge slot, after which the onboard ESP8266 (ESP-1 module) can be enabled and used as a WiFi modem.
The board features the Exar ST16C2552CJ dual UART chip, one channel of which connects to the ESP-1 module, with the other channel used as an uncommitted UART header. The control logic is implemented in VHDL and flashed to the onboard Xilinx CPLD, and a 128 kB RAM module is used as WiFi data buffer.
Although a definite niche product, reading through the forum thread makes one really appreciate the technical complexity and joy once things are beginning to work reliably. It also shows one of the few cases where an ESP-1 module is used for its original purpose: as an easy way to add WiFi functionality with full WiFi and TCP stack, without burdening the main CPU.
Image Source: Hackaday