Questions tagged [floating-point]
Floating point arithmetic: number formats, instruction sets, software and hardware implementations.
69 questions
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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 ...
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What's this weird floating-point format in SPARC
I see some instructions operating on this extended format in SPARC V7
FADDx
Add Extended (FPU Instruction Only)
Operation:
f[rd]x ← f[rs1]x + f[rs2]x
Assembler Syntax:
faddx fregrs1, fregrs2, fregrd
...
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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 ...
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What was the purpose of the System/360 unnormalized floating point add/subtract instructions?
Floating point was optional on System/360, but if it was present, it included separate addition and subtraction instructions that performed postnormalization of the result, or not.
Operands to all ...
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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 ...
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How does ZX Basic represent numbers?
I no longer have my ZX81 or Spectrum, nor their manuals, but I do remember that both floating-point and integer values are stored as 40-bit values (and the motivation for that is addressed in Why does ...
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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 ...
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How did 1977's Car Polo arcade game by Exidy perform hitbox detection, and rigid body collision and movement on the ball?
The link here is a youtube video of Exidy's Car Polo from 1977 : https://www.youtube.com/watch?v=NMljzipOy4s
What blew me away when seeing it in action was the game's hitbox detection for all 4 ...
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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 ...
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Is there any DOS game before Quake era (1996) that makes heavy use of the FPU?
Quake was one of the earliest DOS games to show most gamers the importance of having a fast FPU to play with. Were there any other games (probably 3D) before Quake that started using the FPU?
For ...
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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 ...
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PDP-8 floating point numbers
I'm trying to find a single clear statement of the limits to the numbers represented in the PDP-8's three-word format.
I found the original documents on this, but they are, ahem, not exactly ...
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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 ...
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Examples of floating-point numbers that don’t round-trip losslessly through text conversion in Microsoft BASIC
For a long time I thought it was kind of crazy that 8-bit Microsoft BASIC stores numeric constants in ASCII and has to parse them into its 32- or 40-bit floating point format at runtime. Why not parse ...
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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 ...
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