The Zx Spectrum Ula- How To Design A Microcomputer -zx Design Retro Computer- Instant

He needed a single component to do the work of twenty. He needed a Uncommitted Logic Array—a ULA.

The ZX Spectrum utilized shared memory. Both the Z80 CPU and the ULA needed access to the lower 16KB of RAM. The CPU needed it to execute programs; the ULA needed it continuously to read the display data and draw the screen. He needed a single component to do the work of twenty