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ESP8266-based interface connects classic ZX81 computers to WiFi networks

An ESP8266-based interface connects classic ZX81 computers to FTP servers to quickly load games and programs.

Brazilian maker and retrocomputing enthusiast Victor Trucco showcased a preliminary version of his new ZX81 interface to load programs from the network.

The new prototype evolves from Blue Drive (above), Trucco's previous loader interface that enabled ZX81 computers (and clones with the same bus format) to fetch and load programs from USB thumb drives.

There are literally hundreds of known programs for the ZX81, and many of their cassette tapes were converted to modern formats to be loaded on emulators – or, with an adequate hardware interface, on the original machines.

This new iteration of Trucco's loader interface, called Wifi Drive, connects to an FTP server (local or on the internet), retrieves programs from it and saves them on its internal storage. From this point on, there's no need to keep connected: the ZX81 can load and run the programs issuing simple LOAD commands on its prompt.

During the online stage of the operation, the Wifi Drive is operated from a web browser (running on a mobile phone or a desktop computer, NOT on the ZX81). The web interface enables basic operations like connecting to a WiFi network, uploading local files to the internal memory, and selecting an optional FTP server that hosts additional files.

When operated directly from the ZX81 prompt, the current version implements only the LOAD command (CAT and SAVE are planned). But it's a powerful LOAD command, with 3 formats:

  • LOAD "ZXFILE.P": loads file ZXFILE.P from the local storage, and runs it.
  • LOAD "ZXFILE.P,F": loads file ZXFILE.P from the selected FTP server, and runs it.
  • LOAD "ZXFILE.P,S": loads file ZXFILE.P from the selected FTP server, saves a copy on local storage, and runs it.

Local memory can hold 150~200 files that can be accessed even without WiFi connection. When the LOAD command is issued, the screen flickers in the familiar Sinclair way, but just for seconds, not the minutes we had to wait when using cassette tapes.

In the video above, Trucco himself shows and explains (in portuguese and using a brazilian ZX81 clone called TK85, which mimics the familiar ZX Spectrum form factor) the preliminary version of his new interface.

Jump to 11:14 to see the current hardware configuration: a Blue Drive interface with external jumpers soldered to the ESP12 module where the magic happens. This ESP8266 WiFi module runs the show – as far as connections are involved –, and local files are saved to its memory.

Victor Trucco believes that the final version will be ready shortly, in a matter of months. Happy Hacking!