Questions tagged [floating-point]
Floating point arithmetic: number formats, instruction sets, software and hardware implementations.
69 questions
13 votes
1 answer
480 views
Did CRAY's computers have a guard bit?
The paper What Every Computer Scientist Should Know About Floating-Point Arithmetic uses the Cray's systems as an example of computers without a guard bit: Although most modern computers have a guard ...
- 131
28 votes
2 answers
2k views
When and why is fwait necessary when using the 8087 coprocessor?
I am writing 8086/8087 assembly code that performs floating-point operations, specifically converting numbers to scientific notation. While testing on real hardware (an IBM 5150 with a working 8087 ...
- 533
4 votes
2 answers
444 views
Where can I find a tutorial on using floating point arithmetic via BASIC ROM calls as part of a machine language program
I am trying to reproduce a program I wrote for a Office of Surface Mining scientists back in 1985 that was written on a commodore 128 in BASIC 7.0. The program performed a Monte Carlo simulation of ...
- 41
9 votes
3 answers
2k views
When did Lotus 1-2-3 for DOS start supporting the 8087 math coprocessor?
I upgraded a friend's computer who only used Lotus 1-2-3, and I added memory and dropped in an 8087. Later, I found out their version of Lotus 1-2-3 didn't make use of the 8087. When did Lotus 1-2-3 ...
- 4,391
4 votes
0 answers
274 views
Looking for early examples of extended precision by interpretation
The other day I came across a clever way of implementing variable-length extended precision, dated 1967 (on the BESM-6, apparently as part of the system software available at the time of introduction ...
- 22.3k
9 votes
2 answers
474 views
What floating point libraries were written to meet the IEEE 754 standard before it was accepted in 1985?
The IEEE 754 floating point arithmetic working group began in 1977 and was formally accepted in 1985. One of the original driving factors of the standard itself was Intel who wanted a standard to go ...
- 1,082
18 votes
1 answer
4k views
Why was BASIC's INT() a floor, and not a truncate?
Reading over some older bits I've collected over the years, it appears that some early BASICs used a truncate for their INT function, but this was standardized on floor. Any ideas why? Poking about I ...
- 22.4k
22 votes
1 answer
613 views
Looking for help understanding a 'Reciproot' routine on the Manchester Mark I (1951)
I'm hoping to understand a routine written for the Manchester Mark I [NOTE: a comment from Raffzahn suggests this may be the Ferranti (wikipedia link) and not the Manchester Mark I] which computes ...
- 1,082