Like the Sinclair ZX81, the TS1000 used a form of BASIC as its primary interface and programming language. To make the membrane keyboard less cumbersome for program entry, the TS1000 used a shortcut system of one-letter "keywords" for most commands (e.g., pressing "P" while the cursor was in "keyword mode" would generate the keyword "PRINT"). Some keywords required a short sequence of keystrokes (e.g., SHIFT-ENTER S would generate the keyword "LPRINT"). One notable thing about this version of BASIC was that, unlike other versions where it's optional in a program, the LET command was used extensively for data.