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Macintosh Classic II, FPU / Math Card (Picture)

68kMLA Hardware 57 posts Apr 16, 2013 to Jan 30, 2014
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#15 Fri, 19 Apr 2013 - 18:30 Macintosh Classic II, FPU / Math Card (Picture) — #15
Some bidder sniped it and won it for a dollar over my max bid.

My max bid was 41 bucks. I did not want to pay over that,

I already have the wire wrap, I have those caps in-stock, I have a 16mhz FPU.

I will solder the wires right to the header on the motherboard.

maybe get a little hobby pcb from the shack, to set the FPU on.

I don't have the time to do this now, but it appears less complicated then the InternalHardDriveinaPluShAcK™lol

#16 Fri, 19 Apr 2013 - 22:09 Macintosh Classic II, FPU / Math Card (Picture) — #16
FWIW, the ClassicII dev note has the pinout of the connector. It's pretty much just directly throwing the 68882 on the bus, with the only trick being the 16 bit bus, so doubling up the data lines and using the /DSACK 0 & 1 signals.

I've put some labels on those pictures, to illustrate. For the most part, the labeling refers to the 68882 pins, not necessarily the Classic2's connector. For instance, D16 on the Classic2's connector goes to D0 on the 68882, and I've labeled it D0:

c2fpu.png

c2fpufront.jpg

You can also put a ROM in that socket, up to 3MB worth.

#19 Sat, 20 Apr 2013 - 04:33 Macintosh Classic II, FPU / Math Card (Picture) — #19
I'm really not sure about that. I haven't looked at the ClassicII ROM in particular. There's a good chance it has the EDisk driver, which is what the Classic used to boot (also RAM disk driver, and pcmcia flash card in laptops). That driver looks over some set of addresses (I don't recall how it determines that), for a valid header. So, it might be possible you could put a valid EDisk driver's ROM disk image into ROM there and have it automagically bootable.

#21 Sat, 29 Jun 2013 - 18:04 Macintosh Classic II, FPU / Math Card (Picture) — #21
Nice, how many layers is that board?

Did you guys noodle out the PCB puzzle yet? I doesn't look too bad, especially now with two different layouts to match each other against the documented pinouts of the Memory Slot and the FPU.

Nice graphic, mcd! ;)

#27 Mon, 7 Oct 2013 - 19:38 Macintosh Classic II, FPU / Math Card (Picture) — #27
nope, care if i experiment on your classic ii? I don't have mine any more, ben needed it more then me.
Click to expand...
It's no problem with me. Hopefully once you get it open it will be up to the task. It needs some TLC.

I'm always glad to contribute to the gestalt of Mac 68k knowledge.

#30 Tue, 8 Oct 2013 - 05:49 Macintosh Classic II, FPU / Math Card (Picture) — #30
If somebody came up with a basic but reliable "ROM socket + FPU" card for Classic IIs (even if it were just an FPU socket instead of the actual chip), I'd buy one right away... assuming the cost were reasonable, of course. A board that small shouldn't cost too much to make even in small runs, thanks to the various prototyping services that have sprung up. I bet the worst part would be finding that weird-ass expansion-header connector for a reasonable price. Would a card like that even need any passives on the board, beyond maybe a decoupling cap or two?

#31 Tue, 8 Oct 2013 - 07:15 Macintosh Classic II, FPU / Math Card (Picture) — #31
From what I can tell, you're right, it just needs a few caps, and that's it.

Being able to actually use the ROM capabilities of the slot is very interesting. It would be great to be able to load from ROM like a Classic.

However, as you said, just a card with an FPU socket would be great.

#32 Tue, 8 Oct 2013 - 09:25 Macintosh Classic II, FPU / Math Card (Picture) — #32
the only thing that is slightly strange is that header,

the only 2 guys that i know right off hand that whip up PCB's are:

dougg3

bigmessowires

techknight

if any of these guys wanna whip up a board?

i think mcdermd has the ability, his brother is in the PCB making biz i think.

but he is busier then a worker ant.

i could do it, but i'm more of a stick with with i know type of guy, home brew up something, would end up trying to make a aweful looking but functional prototype thing. Maybe hack off a scsi connector and glue it to a proto board, glue the fpu to the board, and a to b, with those 2 caps/fpu?

#33 Tue, 8 Oct 2013 - 22:05 Macintosh Classic II, FPU / Math Card (Picture) — #33
I think having a socket you can put a custom ROM into is at least as important as having a socket with, or at least for, a 68882. Most older applications never used the FPU because they used to be so rare, but anyone who can download a hacked image might want to be able to plug in a custom ROM.

#34 Thu, 31 Oct 2013 - 13:12 Macintosh Classic II, FPU / Math Card (Picture) — #34
dougg3 could you please make a pcb for this?

also what would be the benefit of having a FPU in a Classic II? /w its crappy 10meg ram limit……

and how many people would want to buy one for their classic II?

I would assume a target price of $45 + shipping would be reasonable?

Can it be done professionally and sold at that target price?

next, bigmessowires, can you make a clone of the current SCSI to Ethernet adaptors that are out there?

i would assume you could get just as much for those as your floppy emu…

that would be the only way for machines like the Plus/ Classic/ Classic II and Portable to get online :)

#35 Thu, 31 Oct 2013 - 16:46 Macintosh Classic II, FPU / Math Card (Picture) — #35
I just happen to have one of the sonnet fpu cards. Don't have a classic iii to test with, but as simple as this card is - I doubt it could ever go bad. Would be happy to take some high-res photos. Or, make an offer if you want the card itself.

If anyone's interested, shoot me a pm.

#36 Thu, 31 Oct 2013 - 19:45 Macintosh Classic II, FPU / Math Card (Picture) — #36
I just happen to have one of the sonnet fpu cards. Don't have a classic iii to test with, but as simple as this card is - I doubt it could ever go bad. Would be happy to take some high-res photos. Or, make an offer if you want the card itself.
If anyone's interested, shoot me a pm.
Click to expand...
$25 plus shipping?

#39 Wed, 6 Nov 2013 - 20:50 Macintosh Classic II, FPU / Math Card (Picture) — #39
Sorry for ignoring everyone, I was busy with the hoard in Tampa. The card was claimed by uniserver, who did send the first PM for it. I got it from an amiga person, who bought it for just the fpu (and pulled it out of. The socket). I'll ask if he has any more, but don't hold any breaths...

#47 Sun, 22 Dec 2013 - 05:15 Macintosh Classic II, FPU / Math Card (Picture) — #47
Sure, sounds good. It’ll make a good project to show the SRCS in the new year. One slight hiccough in the plan, though — does anyone have a compatible 68882 to lend to the effort? I’ll be happy to mail it back afterwards (I have enough caution to solder to a socket, not the chip), but I haven’t any idea what clock speed or what version of the physical package I need. Most VLSI chips came in numerous package types and I’ve no idea where to look for information about it now that this decades-obsolete stuff is getting to be left behind by Freescale’s website. I’ll ask locally too, of course, but I do not anticipate anyone having one (there are few if any Motorola hardware hackers at our meetings just now).

#48 Sun, 22 Dec 2013 - 07:40 Macintosh Classic II, FPU / Math Card (Picture) — #48
Bah, that’s what I get for posting before doing my homework. Turns out the things are only $6 each on Fleabay (with $2 sockets) and any that was ever sold will work just fine in a Classic II, what with its feeble 16MHz bus (no 68882s slower than that were ever sold). The only thing to watch is that if I ever do up a proper design and turn these things into a saleable product I need to stay away from the FN-marked PLCC version. It isn’t lead-free-standards compliant.

I will keep you all posted on my progress. Do not expect great rapidity.

#49 Sun, 22 Dec 2013 - 13:34 Macintosh Classic II, FPU / Math Card (Picture) — #49
Faster fpus will work fine. I bought and put in faster fpus in my color classic. It's a lot like ram in that respect, you can go faster , just not slower. I'll look and see if I have any 68882's around.

#50 Sun, 26 Jan 2014 - 04:04 Macintosh Classic II, FPU / Math Card (Picture) — #50
Still hoping someone can lend a 68882 to the effort. I can probably afford the $2 socket, but $10 for the chip+shipping is a bridge too far at this point (more needed for groceries and gas). Anyone out there feeling helpful?

#53 Thu, 30 Jan 2014 - 18:49 Macintosh Classic II, FPU / Math Card (Picture) — #53
...A bit off topic for the 'FPU card' side of it, but AFAIK the expansion slot on the Classic II also handles the external ROM slot as well (up to 1MB IIRC).

If you're designing a board at all, why not include the potential future ROM upgrades by including a ROM socket as well?

I'd love to see a "IIsi" style ROM for the CII in the future... ;)

#54 Thu, 30 Jan 2014 - 19:19 Macintosh Classic II, FPU / Math Card (Picture) — #54
...A bit off topic for the 'FPU card' side of it, but AFAIK the expansion slot on the Classic II also handles the external ROM slot as well (up to 1MB IIRC).
Click to expand...
It’s actually 2–3 MiB, varying according to a jumper on the motherboard. The Classic II can have up to 4 megs of ROM, and the jumper determines whether 1 or 2 of those megabytes are on the motherboard.

If you're designing a board at all, why not include the potential future ROM upgrades by including a ROM socket as well?
I'd love to see a "IIsi" style ROM for the CII in the future... ;)
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Well, yes, that’s exactly what I’m working towards. See earlier posts in this thread.

#55 Thu, 30 Jan 2014 - 19:29 Macintosh Classic II, FPU / Math Card (Picture) — #55
Do you have one yet?
Shipping is a bit prohibitive from/to Canada but I can dredge one up and send if need be.
Click to expand...
Alas, I haven’t had a whisper. And while I am grateful to you for volunteering to lend one of yours, I agree that Canuckistani postal rates are prohibitively expensive. I don’t know the detailed fee schedule but it’d likely be more expensive even than buying one from a US source on Fleabay and putting my address as the destination.

One thing I can say is that any 68882 at all will work — the FN-marked ones may be a problem to resell in a finished product due to RoHS rules, but that hardly matters for a prototype.

#56 Thu, 30 Jan 2014 - 19:34 Macintosh Classic II, FPU / Math Card (Picture) — #56
I am pretty sure if someone wants to take a 50 pin scsi cable. cut it and just solder the wires to an fpu socket, then you will have a home brew FPU for your Classic II.
Click to expand...
Broadly correct, but you’d likely want to kludge a decoupling cap or two as well. When you add in the ROM socket on top of that, a real board starts to look like a good idea.

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