It was thus said that the Great Steve Lewis via cctalk once stated: > Great discussions about BASIC. I talked about the IBM 5110 flavor of > BASIC last year (such as its FORM keyboard for quickly making structured > input forms), and recently "re-learned" that it defaults to running with > double-precision. But if you use "RUNS" instead of "RUN" then the same > code is run using single-precision (but I haven't verified yet if that > translates into an actual runtime speed difference). I think most of the > "street BASICs" used single precision (if they supported floats at all). > But speaking of Microsoft BASIC, I think Monte Davidoff is still around > and deserves a lot of credit for doing the floating point library in the > initial Microsoft BASIC (but it's a bit sad that history has lost the names > of individual contributors
I think most of the "street BASICs" were written before IEEE-754 (floating point standard) was ratified (1985 if I recall). Microsoft's floating point [1] was five bytes long---four bytes for the mantissa, and one byte for the exponent, biased by 129. I did some tests a month ago whereby I tested the speed of the Microsoft floating point math on the 6809 (using Color Computer BASIC) vs. the Motorola 6839 (floating point ROM implementing IEEE-754), and the Microsoft version was faster [2]. -spc [1] https://en.wikipedia.org/wiki/Microsoft_Binary_Format [2] https://boston.conman.org/2024/03/01.1
