ZX Spectrum System Tour: Text Mode – Bumbershoot Software

The ZX Spectrum had minimal firmware interface consistency compared to competitors like Commodore and MSX, forcing developers to make direct calls into the system ROM rather than using standardized jump tables. This design flaw is illustrated by the Timex Sinclair 2068's incompatible ROM, which rendered almost all Spectrum software incompatible and likely contributed to its market failure. This article begins exploring machine language programming on the 48K Spectrum, covering system organization, text-based displays, and input handling.