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Super rare Macintosh II Daystar PDS adapter
Posted by: Unknown_K on 2016-10-02 19:39:37
Wouldn't the FPU in the 68040 interfere with the 68882 (unless you have a LC 040 with no FPU)?
Posted by: EvieSigma on 2016-10-02 19:58:36
I'm interested in the idea of an expansion for LC040 machines with a FPU add-on...unless the 030 compatible FPU is even harder to find than a 33MHz full 040.
Posted by: Bunsen on 2016-10-02 23:54:53
I don't think they're compatible.
 

Wouldn't the FPU in the 68040 interfere with the 68882 (unless you have a LC 040 with no FPU)?
No, I think the system just ignores the off-chip FPU.
 
Posted by: Anonymous Freak on 2016-10-02 23:57:47
This rings a bell, I seem to recall that the PowerBook Duo 280c had a problem in that it wasn't possible to have an FPU, where the '030 Duos could use an -882 in the DuoDock.
Posted by: herpderp on 2018-12-03 21:43:49
I realize this is a thread necro, but if anyone is interested, I have one of these mythical PDS adaptors, albeit for the Macintosh II.  It is different (and maybe rarer?) than the IIx one, as it pulls data and signal from the MC68851 PMMU memory management unit as well as the MC68020 CPU to work its magic.   The card consists of a PDS slot glued to the 68020 bus via some PAL chips, and a programmable ROM (probably some boot time glue to deal with the bus signals/INTs/MMU). PM me if interested.  I'm not interested in price gouging, I'd sell it cheap. 

20181204_004118.jpg
Posted by: herpderp on 2018-12-03 21:44:06
20181204_004136.jpg
Posted by: herpderp on 2018-12-03 22:03:12
Also, this may be helpful  🙂

https://html.alldatasheet.com/html-pdf/4166/MOTOROLA/MC68851/258/1/MC68851.html
Posted by: CC_333 on 2018-12-03 23:04:21
How cheap is cheap? 🙂

I actually have a Mac II, and I *might* actually have a use for this (dunno what it'd be (what's it for?), but I'd figure something out), if it's cheap enough for me to afford.

c
Posted by: herpderp on 2018-12-04 07:06:34
I can see there is some price history floating around on the internet/eBay, and it seems to be worth anywhere from $25 to $40.  I'd let it go for like $10-15 I guess, or maybe less if that's not reasonable.  I don't have a use for this anymore, someone else may as well enjoy it.
Posted by: CC_333 on 2018-12-04 14:08:52
Hmm, OK. I can probably afford that in a week or so.

I guess I'll take it, if nobody else has!

c
Posted by: Unknown_K on 2018-12-04 18:24:35
A Mac II and IIcx adapter recently sold on ebay cheap. I have one of both. I think a working Mac II is probably as hard to find as the Daystar adapter.
Posted by: Paralel on 2018-12-05 00:16:28
I don't think they're compatible.
 

No, I think the system just ignores the off-chip FPU.
 
A very late reply... But the 68882 can be used, but not like a typical "FPU" with the 'LC040. It has to be run in "Peripheral" mode as an external device. So, it would be very slow. This was done on purpose by Moto' to prevent people from using the 68882 with the 'LC040 like it was used with the '030, as a cheaper option than a full '040. There was one originally planned for the 540c card cage by Sonnet, but they dropped it before it went to production because they realized 1) Not much demand 2) The performance was truly awful.
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