3 May
2024
3 May
'24
9:31 p.m.
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