The ZX Spectrum had a small speaker, but the only way to “drive” it was a single bit on one of the Z80 I/O ports. By sending zeroes and ones at an appropriate rate you could get a musical note. Pretty basic square wave stuff….

The Sinclair “ZX” family of machines used a Z80 processor. Technically speaking a Z80A which the Sinclair manuals liked saying “goes faster”. The Z80 is actually a rather powerful CPU by 8-bit standards, having six general purpose 8-bit registers (B, C, D, E, H and…

The first ever computer I owned was a Sinclair ZX81, and it was a present along with a 16K memory expansion unit, the computer by itself having only 1K of memory! The ROM of the ZX81 was only 8K in size, yet included a full…