wayne@pur-phy (Wayne K. Schroll) (02/01/89)
I have heard that the 68882 is pin-equivalent to the 68881. Is this
true? If so, can I just pop the '881 out of my Mac II (A/UX) and drop
in the '882? I have also heard that the '882 will provide a speed
increase of about a factor of two on floating point operations. Is this
true? Is there anything special I should know since my Mac II runs A/UX?
Finally, does anyone know of a good place to purchase a 68882 chip, and
it's approximate cost? Thanks for any information you can provide.
Waynerick@Apple.COM (Rick Auricchio) (02/02/89)
In article <1927@pur-phy> wayne@pur-phy (Wayne K. Schroll) writes: > > I have heard that the 68882 is pin-equivalent to the 68881. Is this >true? If so, can I just pop the '881 out of my Mac II (A/UX) and drop >in the '882? It is pin-compatible, but see below. > Is there anything special I should know since my Mac II runs A/UX? Yes. The '882 has a larger saved register stack during interrupts, which required a changed to the UDOT stack space in A/UX 1.0.1 (the one which runs on the 68030). If you're running 1.0, certain operations (naturally, I don't know which) can stuff more bytes than there's room for, causing trouble. I don't think it's a panic, but any stack overflow is generally bad. >Finally, does anyone know of a good place to purchase a 68882 chip, and >it's approximate cost? Thanks for any information you can provide. Sorry, I don't know either on this one... BTW, 1.0.1 is essentially 1.0 with trivial changes...'030 and '882 support, and "tolerating" the FDHD hi-density floppy being the most notable. If you don't have the hardware need for it, you shouldn't worry about it. -- Rick Auricchio, Apple Computer Inc, 20525 Mariani Av MS 27AJ Cupertino CA 95014 sun!apple!rick OR rick@apple.COM Malibu N4364D (408) 974-4227 People who think money can't buy happiness are shopping in the wrong places. My opinion is my own. My employer? They use a windsock and a fire extinguisher.
ralphw@ius3.ius.cs.cmu.edu (Ralph Hyre) (02/09/89)
>... can I just pop the '881 out of my Mac II (A/UX) and drop in the '882?
[no] ... The '882 has a larger saved register stack during
interrupts, which required a changed to the UDOT stack space
in A/UX 1.0.1 (the one which runs on the 68030).
Didn't Motorola document a way to interrogate the FPC to ask how large its
stack and other frames will be? If so, then it's too bad the NOBODY
seems to have used it in their OS kernels, thereby requiring an OS upgrade
when the '882 came out. (on a Sun, we're told that dropping an '882 in
will typically cause the u_area to be overwritten, with bad results.)
--
- Ralph W. Hyre, Jr.
Internet: ralphw@{ius{3,2,1}.,}cs.cmu.edu Phone:(412) CMU-BUGS
Amateur Packet Radio: N3FGW@W2XO, or c/o W3VC, CMU Radio Club, Pittsburgh, PA
"You can do what you want with my computer, but leave me alone!8-)"
-- phil@Apple.COM (Phil Ronzone) (02/09/89)
In article <4225@pt.cs.cmu.edu> ralphw@ius3.ius.cs.cmu.edu (Ralph Hyre) writes: >>... can I just pop the '881 out of my Mac II (A/UX) and drop in the '882? > >[no] ... The '882 has a larger saved register stack during > interrupts, which required a changed to the UDOT stack space > in A/UX 1.0.1 (the one which runs on the 68030). > >Didn't Motorola document a way to interrogate the FPC to ask how large its >stack and other frames will be? If so, then it's too bad the NOBODY >seems to have used it in their OS kernels, thereby requiring an OS upgrade >when the '882 came out. (on a Sun, we're told that dropping an '882 in >will typically cause the u_area to be overwritten, with bad results.) > - Ralph W. Hyre, Jr. Sure, Motorola documents these kinds of facts. The documentation is nice and pretty and generally available just a few months AFTER the part is in production and shipping. That means over a year after the part has had the software frozen for it. (Only 50% tongue-in-cheek ...) The very first PMMU Apple ever (tried) to plug into the early prototype Mac IIs didn't fit in the socket! Someone at Motorola decided it needed a few more power pins ... and somehow the one-page tech note missed us. I suppose the day that future hardware parts are built exactly to the specifications written before the part is produced, will be the day that future software will have to be built exactly to the specifications written before the software is produced (assuming this industry STARTS writing specifications before writing code) :-) :-) :-) +------------------------+-----------------------+----------------------------+ | Philip K. Ronzone | A/UX System Architect | APPLELINK: RONZONE1 | | Apple Computer MS 27AJ +-----------------------+----------------------------+ | 10500 N. DeAnza Blvd. | There's a million things we'd like to say, but we | | Cupertino CA 95014 | aren't supposed to piss anybody off. Oh well ... | +------------------------+----------------------------------------------------+ |{amdahl,decwrl,sun,voder,nsc,mtxinu,dual,unisoft}!apple!phil | +-----------------------------------------------------------------------------+