[keithpeter]

bas55 [1] is the closest I can find to a Dartmouth style basic (so 70s rather than 80s). Alas constants are truncated at 6 places (internal calculations are all doubles). It compiles fine and works well complete with LOAD, SAVE and limited line editing.

Does anyone know of a portable basic interpreter that supports double precision all through?

The kind of stuff I (used to) do [2] requires more than 6 figures.

[1] https://jorgicor.niobe.org/bas55/

[2] https://sohcahtoa.org.uk/kepler/moon2.html

[Falkon1313]

Maybe FreeBASIC would be useful, (although it's a compiler rather than an interpreter, and a more modern dialect than 70s BASIC, mostly compatible with QBASIC/QuickBASIC). https://www.freebasic.net/

It handles 64-bit doubles: https://www.freebasic.net/wiki/wikka.php?wakka=KeyPgDouble