Talk:Motorola 68881

To-do items include:


 * Release dates!
 * A list of all computers to use these FPUs
 * Their cost over time
 * A list of the clock rates available by year
 * Perhaps a list of some of the software packages that were the heaviest users of these FPUs, if you will, like Mathematica on the Mac II
 * And some info on software emulation
 * The first Power Macs were incompatible with 68K programs that used 68881 instructions because the emulator didn't support the FPU, and there was that Virtual 68881 product that was briefly popular. (Ironic seeing the PowerPC's strong FPU performance.)  A mildly interesting footnote to the history of the 68881.

A quote from an Apple employee was that they put the FPU in the Mac II because they looked at some benchmarks and said "wow". Seemed engineer driven for sure; I'd estimate that 99% of user-hours on the Mac II family didn't see a single FPU instruction executed.

These days floating-point performance is really important for games because of all the 3D math, but games weren't a driver for the 68881. At the time, FPUs were rare, and sometimes Apple would make a Mac II computer without an FPU, aimed at consumers (like the LC and the IIsi), so the market probably wasn't large enough to take the effort. And Doom had used integer math; developers (even those few making original Mac games) probably figured integer math was good enough. Tempshill 18:52, 2 May 2005 (UTC)

Size of Registers
According to the Programmer's Reference Manual (M68000PRM.PDF @ Freescale) referenced on this page, the 6888x FPUs use "extended-precision" in all 8 FPx registers.

Extended precision is NOT the 8087's 'long double', but rather a 96-bit representation.

Commodore's Rom Kernel Reference Manual: Libraries book discusses this too in the IEEE/ffp math library chapters.

I've done the 'be bold' thing and corrected the text. Renegrade (talk) 09:01, 18 October 2011 (UTC)

Document creators of the 68881 please
I encourage anyone reading this to document the names of the awesome 68881 engineers. Hm. I might have one on linkedin.

I recall IBM hired a great one, into our AIX slash PC/RT product line. I know he did the transcendentals, and more. I was just a Sr. Assoc. but happened to have quietly written an all-but-Nans on-the-fly 754-committee-congruent math package in assembkler a couple years earlier (the 1st 1/2 bit accurate production code in IBM, I would venture. "Production" being debatable - the 5280 group sadly was killed by the PC before my code could ship, other than as a PTF.)

I'll add his name here when I recall it. Old school mathematician-programmers shouldnt be forgotten.

Please, people, here and in so many other tech pages, discover the names involved. Pioneers need to be remembered, not just the things they built. Some chose and still choose anonymity, but so what? Historians can still record them. Not just the corporations and devices built on their efforts. Key inventors can still be found, via linkedin's network, but they're in their 60s and beyond, so start your research asap. Imagine some relic of an Apple kernel software engineering manager kicking your butt.

Gtg. Mounting disabling typing pain makes me megacrazy, sorry, bane of my career. Enjoy the random. — Preceding unsigned comment added by Rad314 (talk • contribs) 15:16, 24 March 2020 (UTC)