Z80 Assembly Desktop Environment Released for ZX Spectrum 48K

Desktop Environment for Vintage Hardware

A new graphical desktop environment, ZXDesk, has been developed for the ZX Spectrum 48K. This system, written entirely in Z80 assembly, brings modern desktop features to a machine released in 1982 with significant hardware constraints. It operates within the 48K RAM limit of the original device.

Feature Set and Performance

ZXDesk includes overlapping windows with Z-order and focus, pull-down menus, a heap, an event queue, and a storage layer with swappable backends. Applications such as a notepad, clock, calendar, two-pane file manager, and a settings panel are integrated. The system is capable of dragging a window within a single 69,888 T-state frame, demonstrating its optimized performance on a 3.5 MHz Z80 CPU.

Technical Implementation and Tooling

The project was developed using a local toolchain including pasmo 0.5.5. It supports building for both 48K and 128K Spectrum models. The environment can run on actual ZX Spectrum hardware, not just emulators, and supports esxDOS for file management via an emulated DivMMC. Build flags allow for specific configurations, such as self-dragging demos or synthetic input testing.

Motivation and Impact

The developer created ZXDesk to realize a long-held ambition of bringing a desktop-like experience to the ZX Spectrum, similar to GEM on the Atari ST. The project emphasizes practical solutions derived from direct machine measurements rather than theoretical reasoning, offering insights for other developers working with similar vintage hardware.