YS MegaBasic was a BASIC programming language interpreter for the 1982 Sinclair Research ZX Spectrum microcomputer, written by Mike Leaman.When loaded it left the user 22K of usable memory. YS MegaBasic allowed keywords to be spelled out letter-for-letter, which was quicker if the user had fitted a full-size full-travel keyboard to their machine, a very popular modification for serious users.