4 May
2024
4 May
'24
1:19 a.m.
On Fri, May 3, 2024 at 7:49 PM Paul Koning via cctalk
<cctalk(a)classiccmp.org> wrote:
The "4WD" (as opposed to "3WD") tells you you're on a machine
that
uses the four word long floating point.
BASIC-PLUS (part of RSTS) had a weird floating point
history. The original version, through RSTS V3, used 3-word floating point: two words
mantissa, one word exponent. Then, presumably to match the 11/45 FPU, in version 4A they
switched to your choice of 2 or 4 word float, what later in the VAX era came to be called
"F" and "D" float.
Interesting. The original (pre-Series II) HP 3000 systems in the mid
1970s also started with a three (16-bit) word floating point format
and later switched to supporting both 2 and 4 word formats. One of the
only ways you would see this is in the header line that displays when
you run BASIC::
:BASIC
HP32101B.00.26(4WD) BASIC (C)HEWLETT-PACKARD CO 1979