ZX Spectrum graphic modes - Wikipedia

Penetrator (video game) - Wikipedia

Spectrum Simulator - C64-Wiki

Planet X3 is Here! And with new video modes! - The 8-Bit Guy

Contra (video game), Konami Wiki

Gunfright - Wikipedia

ZX Spectrum character set - Wikipedia

Doom (ZX Spectrum) - The Doom Wiki at

ZX Spectrum graphic modes - Wikipedia

ZX Spectrum graphic modes - HandWiki

Guide:Video card support in DOSBox‐X · joncampbell123/dosbox-x Wiki · GitHub

Sinclair Computers: Gone But Not Forgotten